Use of yeast for treating white faeces syndrome in shrimp

Abstract

The invention relates to an active yeast of the Saccharomyces genus for use in the treatment of white faeces syndrome (WFS) in shrimp. The invention also relates to a food composition for shrimp comprising at least one active yeast of the Saccharomyces genus.

Description

[0001] USE OF YEAST FOR THE TREATMENT OF WHITE FECES SYNDROME IN SHRIMP

[0002] Scope of the invention

[0003] The present invention relates to the treatment of white feces syndrome in shrimp, such as whiteleg shrimp and giant tiger shrimp, using an active yeast. The invention also relates to shrimp feed compositions comprising an active yeast.

[0004] Technical background

[0005] White Feces Syndrome (WFS) is an emerging disease affecting shrimp farms, particularly those raising Penaeidae shrimp in tanks or ponds. This syndrome is characterized by the presence of white fecal filaments floating in the water of the rearing tanks. It leads to high mortality among the shrimp, as well as stunted growth, resulting in significant economic losses for farmers. This syndrome is also associated with reduced feed intake by affected shrimp, coupled with a decline in feed conversion ratio, increased size heterogeneity, and the development of ultrastructural disorders in their hepatopancreas and intestines, along with discoloration of these two organs and a soft carapace.

[0006] White feces syndrome has a complex etiology. It can have various, often multiple, causes that are not yet fully understood. It results from an alteration of the shrimp's gut microbiota, which can be caused, promoted, or exacerbated by, among other things, fungal (particularly Enterocytozoon hepatopenaei (EHP)) and / or bacterial (particularly Vibrio and / or Propionigenium) infections, poor-quality feed containing antinutritional factors or mycotoxins, and the presence of algal toxins and / or gregarins. Currently, there are no effective treatments available for white feces syndrome. Some approaches have been explored to try to prevent or control this disease, such as administering probiotic bacteria to the shrimp.

[0007] There is a real need to develop a way to treat white feces syndrome in shrimp that is effective, economical and easy to implement.

[0008] Summary of the invention

[0009] The invention relates primarily to an active yeast of the genus Saccharomyces for its use in the treatment of white feces syndrome (WFS) in shrimp.

[0010] In some embodiments, the treatment is a prophylactic treatment and / or a curative treatment.

[0011] In some embodiments, the yeast is chosen from the group consisting of the species Saccharomyces cerevisiae, Saccharomyces cerevisiae var. boulardii, and mixtures thereof, preferably the yeast is of the species Saccharomyces cerevisiae.

[0012] In some embodiments, the yeast is obtained from a strain selected from the group consisting of the strain filed with the CNCM on December 2, 2010 under number I-4407, the strain filed with the CNCM on August 30, 2017 under number I-5223 and combinations thereof.

[0013] In some embodiments, said yeast is in the form of dry yeast.

[0014] In some embodiments, the shrimp is chosen from the group consisting of white-legged shrimp, giant tiger shrimp and mixtures thereof.

[0015] In some embodiments, the shrimp is present in a tank containing water, and said yeast is administered into the water of the tank.

[0016] In some embodiments, the yeast is administered into the basin water in an amount of 0.005 to 5 g / m³ 3 of water / day, preferably 0.01 to 2 g / m³ 3 water / day, preferably 0.02 to 1 g / m³3 of water / day.

[0017] In some embodiments, said yeast is administered in a shrimp food composition.

[0018] In some embodiments, the composition comprises a core and a coating layer surrounding said core, the yeast being present in the coating layer. In some embodiments, the yeast is included in the food composition in an amount of 0.005 to 5% by mass, preferably 0.01 to 2% by mass, more preferably 0.02 to 1% by mass, and even more preferably 0.05 to 0.5% by mass, relative to the total mass of the food composition.

[0019] In embodiments, the yeast is formulated in liquid form, in lyophilized form, in tablet form, in capsule form, in granule form, in gel form, in powder form, in microgranulated powder form, in effervescent form, in form with gradual and / or controlled release, and / or in a water-soluble sachet.

[0020] In some embodiments, white fecal syndrome is caused by infection with at least one microorganism selected from fungi of the genus Enterocytozoon, preferably Enterocytozoon hepatopenaei, bacteria of the genus Vibrio, preferably Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio harveyi, Vibrio fluvialis, Vibrio vulnificus, Vibrio sinaloensis, Vibrio mimicus, Vibrio cholerae and / or Vibrio anguillarum, bacteria of the genus Propionigenium, bacteria of the genus Photobacterium, preferably Photobacterium damselae, gregarines and combinations thereof.

[0021] The invention also relates to a shrimp food composition comprising at least one active yeast of the genus Saccharomyces, preferably of the species Saccharomyces cerevisiae, said composition preferably comprising a core and a coating layer surrounding said core, in which the coating layer comprises said at least one active yeast of the genus Saccharomyces.

[0022] In some embodiments, the active yeast is obtained from a strain selected from the group consisting of the strain filed with the CNCM on December 2, 2010 under number I-4407, the strain filed with the CNCM on August 30, 2017 under number I-5223 and combinations thereof.

[0023] The invention also relates to a food composition as described above for its use as a medicine in shrimp.

[0024] The present invention addresses the need described above. More specifically, it provides an effective, preventative, and curative treatment for white feces syndrome affecting shrimp, compatible with shrimp rearing conditions, and easy to administer, while remaining economical. Furthermore, the treatment according to the invention does not develop resistance to the disease, as observed with antibiotic treatments, and it is not inhibited by the administration of antibiotics (and is therefore compatible with their use) because it is not based on bacteria.

[0025] This is achieved through the use of a live (or active) yeast of the genus Saccharomyces. Surprisingly, it has been discovered that administering this yeast to shrimp not only prevents the onset of the disease but also reduces the symptoms of the syndrome in affected shrimp. Specifically, administering this yeast to shrimp increases their survival rate, increases their mass or size, decreases their feed conversion ratio, improves their intestinal health, and reduces size variations among the shrimp.

[0026] Detailed description

[0027] The invention is now described in more detail and in a non-limiting manner in the following description.

[0028] In this text, unless expressly stated otherwise, all percentages (%) indicated are percentages by mass.

[0029] In this text, the quantities indicated for a given species / substance may apply to that species / substance according to all its definitions (as mentioned in this text), including more restricted definitions.

[0030] The invention relates primarily to a yeast for use in the treatment of white feces syndrome in shrimp. For the purposes of this invention, "treatment" includes both prophylactic and curative treatments. Thus, the yeast according to the invention can be used to prevent white feces syndrome and / or to cure or alleviate it.

[0031] Preferably, the treatment according to the invention results in an increase in the survival rate of shrimp, compared to untreated shrimp.

[0032] Preferably, the treatment according to the invention results in an increase in the individual mass of the shrimp, compared to untreated shrimp.

[0033] Preferably, the treatment according to the invention results in a decrease in the feed conversion ratio in shrimp, compared to untreated shrimp.

[0034] Preferably, the treatment according to the invention results in a decrease in size / mass disparities between shrimp (or, in other words, results in an increase in the homogeneity of shrimp sizes / mass), compared to untreated shrimp.

[0035] Preferably, the treatment according to the invention results in an improvement in the intestinal health ("gut health" in English) of the shrimp, compared to untreated shrimp.

[0036] Yeast

[0037] The yeast according to the invention is an active yeast. By "active yeast" is meant a living yeast, that is to say a yeast whose metabolism is active or reactivatable (as opposed to a dead yeast whose metabolism has been irretrievably stopped).

[0038] The yeast according to the invention is a yeast belonging to the genus Saccharomyces. Examples of usable yeasts according to the invention include the species Saccharomyces cerevisiae, Saccharomyces cerevisiae var. boulardii, Saccharomyces bailii, Saccharomyces carlsbergensis, Saccharomyces delbrueckii, Saccharomyces exiguus, Saccharomyces fermentati, Saccharomyces florentinus, Saccharomyces fragilis, Saccharomyces fructuum, Saccharomyces heterogenicus, Saccharomyces oleaginosus, Saccharomyces rosei, Saccharomyces steineri, Saccharomyces kefir, Saccharomyces kluyveri, and all combinations thereof.

[0039] More specifically, the yeast is chosen from the species Saccharomyces cerevisiae, Saccharomyces cerevisiae var. boulardii and combinations thereof.

[0040] Preferably, the yeast according to the invention is a Saccharomyces cerevisiae yeast.

[0041] Advantageously, the yeast is obtained from a strain selected from the group consisting of the strain filed with the CNCM on December 2, 2010 under number I-4407, the strain filed with the CNCM on August 31, 2016 under number 1-5128, the strain filed with the CNCM on August 31, 2016 under number 1-5129, the strain filed with the CNCM on August 31, 2016 under number 1-5130, the strain filed with the CNCM on August 31, 2016 under number 1-5131, the strain filed with the CNCM on August 30, 2017 under number I-5222, the strain filed with the CNCM on August 30, 2017 under number I-5223 and combinations thereof.

[0042] Preferably, the yeast is obtained from a strain selected from the group consisting of the strain filed with the CNCM on December 2, 2010 under number I-4407, the strain filed with the CNCM on August 30, 2017 under number I-5223, and combinations thereof.

[0043] The term "yeast strain" refers to a relatively homogeneous population of yeast cells. A yeast strain is obtained from the isolation of a clone, a clone being a population of cells obtained from a single yeast cell.

[0044] The appropriate culture medium and growing conditions for a yeast strain are readily determinable by a person skilled in the art. For example, yeast can be obtained by culturing a strain in a culture medium as described in the reference book "Yeast Technology," G. Reed and T.W. Nagodawithana, 2 ème edition, 1991 (ISBN 0-442-31892-8).

[0045] The yeast according to the invention can be in the form of dry yeast, fresh yeast, or yeast with intermediate moisture content. "Dry yeast" means any yeast having a dry matter content greater than 90% by mass, preferably ranging from approximately 92% to 96% by mass. The dry matter content can, for example, be determined by the drying method, after drying in an oven for a minimum of 17 hours at a temperature of 103°C.

[0046] The term "fresh yeast" preferably means yeast with a dry matter content of less than 50% by mass. Fresh yeast may be in liquid form (i.e., preferably with a dry matter content of less than 20% by mass, more preferably from 10 to 18% by mass) or in compressed form (i.e., preferably with a dry matter content of 20% to less than 50% by mass, more preferably from 25 to 35% by mass).

[0047] The term "intermediate moisture yeast" preferably refers to yeast having a dry matter content of 50% to less than 90% by mass. Such yeast may, in particular, comprise 70% to 85% dry matter by mass. The intermediate moisture yeast according to the invention may or may not be frozen.

[0048] Preferably, the yeast should be dry yeast. Dry yeast has the advantage of a longer shelf life.

[0049] The dry yeast according to the invention can in particular be an active dry yeast or an instant active dry yeast.

[0050] The active dry yeast or instant active dry yeast according to the invention comprises a yeast dry matter content exceeding 90% by mass, preferably a dry matter content of 92% to 96% by mass. The active dry yeast can be obtained by dehydrating pressed or liquid yeast through the combined action of heat (at low temperature) and mechanical activity, which transforms a paste-like product (pressed or liquid yeast) into a dry product, particularly in the form of spherules, while preserving its viability. For example, the active dry yeast can be obtained by extrusion and fluidized bed drying of pressed or liquid yeast.

[0051] The active dry yeast according to the invention can in particular be prepared by a process comprising the following steps:

[0052] - culture of a yeast strain in a culture medium, in particular in several stages, more particularly first in semi-anaerobic conditions, then in aerobic conditions;

[0053] - separation by centrifugation of the yeast thus produced from its culture medium, to obtain a liquid yeast cream or a liquid yeast, preferably containing 10 to 30% by mass of dry matter, more preferably 12 to 25% by mass of dry matter;

[0054] - mixing liquid yeast cream or liquid yeast with a brine, in particular a brine based on sodium chloride;

[0055] - dehydration of the mixture to obtain dehydrated yeast;

[0056] - extrusion of dehydrated yeast to obtain extruded yeast;

[0057] - drying of the extruded yeast to obtain dry yeast.

[0058] Active dry yeast is preferably in the form of spherules, preferably with a diameter of 0.1 mm to 2.5 mm, and preferably with a water content of 4% to 8% by mass.

[0059] Instant active dry yeast has the unique characteristic of not requiring rehydration before being incorporated into a product. It can be obtained by dehydrating pressed or liquid yeast using a hot air gradient, which transforms a paste-like product (pressed or liquid yeast) into fine, dry granules (while retaining its activity). Instant dry yeast is then preferably packaged in an oxygen-free environment to ensure its stability.

[0060] The yeast according to the invention can be in any suitable form, including the forms described above (particularly in the form of spherules or vermicelli). The yeast according to the invention can be an active yeast adapted to weak organic acids. "Active yeast adapted to weak organic acids" means a yeast whose tolerance to a given weak organic acid is increased through prior exposure to that acid ("Effect of benzoic acid on growth yield of yeasts differing in their resistance to preservatives," Warth, Appl. Environ. Microbiol., 1988, vol. 54, no. 8, pp. 2091–2095). The growth and fermentative capacity of the adapted yeast are thus not inhibited when the yeast is exposed to a weak organic acid for at least a second time. "Weak organic acids" means organic acids as such and their salts.Preferably, the weak organic acids are chosen from the group consisting of propionic acid, benzoic acid, acetic acid, butyric acid, citric acid, formic acid, fumaric acid, lactic acid, malic acid, sorbic acid, and their salts, particularly their calcium or sodium salts. Preferably, the yeast is adapted to a salt of propionic acid and / or a salt of benzoic acid, more preferably to calcium propionate and / or sodium benzoate.

[0061] WFS processing

[0062] The term "white feces syndrome" conventionally refers to diseases characterized by the production by the shrimp of white fecal filaments floating in the water.

[0063] The white stool syndrome treated according to the invention can have any possible cause. In particular, it can originate from an infection by one or more microorganisms, or any other cause. Not all microorganisms whose infection can cause or contribute to the development of white stool syndrome have been identified to date. The treatment according to the invention is applicable regardless of the microorganism(s) causing the white stool syndrome.

[0064] In embodiments, the white feces syndrome treated according to the invention is caused in shrimp by an infection by at least one fungus of the genus Enterocytozoon, preferably by at least Enterocytozoon hepatopenaei.

[0065] In some embodiments, the white feces syndrome treated according to the invention is caused in shrimp by infection with at least one bacterium of the genus Vibrio. Examples of bacteria include Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio harveyi, Vibrio fluvialis, Vibrio vulnificus, Vibrio sinaloensis, Vibrio mimicus, Vibrio cholerae, Vibrio anguillarum, and combinations thereof.

[0066] In embodiments, the white feces syndrome treated according to the invention is caused in shrimp by an infection with at least one bacterium of the genus Propionigenium.

[0067] In embodiments, the white feces syndrome treated according to the invention is caused in shrimp by an infection by at least one bacterium of the genus Photobacterium, such as Photobacterium damselae.

[0068] In some embodiments, the white feces syndrome treated according to the invention is caused in the shrimp by an infection with at least one gregarin.

[0069] The white fecal syndrome treated according to the invention can, in particular, be caused by co-infection with two or more of the microorganisms mentioned above, for example, by co-infection with at least one fungus of the genus Enterocytozoon and one bacterium of the genus Vibrio. The fungus of the genus Enterocytozoon and the bacterium of the genus Vibrio can, more specifically, be as defined above.

[0070] The shrimp treated according to the invention can be any existing shrimp. In particular, animals belonging to the infraorder Caridea, the infraorder Stenopodidea, the suborder Dendrobranchiata, the order Euphausiacea, the order Stomatopoda, the order Mysida and the family Caprellidae may be mentioned.

[0071] Preferably, the shrimp being processed is a shrimp from the suborder Dendrobranchiata, more preferentially from the family Penaeidae, and even more preferentially from the genus Penaeus, for example chosen from the white-legged shrimp (Litopenaeus vannamei), the giant tiger shrimp (Penaeus monodon), the blue shrimp (Penaeus stylirostris), the fleshy shrimp (Penaeus chinensis), the imperial shrimp (Penaeus japonicus), the Indian white shrimp (Penaeus indicus), the banana shrimp (Penaeus merguiensis) and mixtures thereof.

[0072] Even more preferably, the shrimp treated according to the invention is chosen from the group consisting of the white-legged shrimp (Litopenaeus vannamei, also known as Penaeus vannamei), the giant tiger shrimp (Penaeus monodon) and mixtures thereof.

[0073] Advantageously, the shrimp treated according to the invention is a farmed shrimp. Preferably, the treated shrimp is present in a tank or pond filled with water (this water may be salt water or fresh water, preferably salt water).

[0074] The yeast according to the invention can be administered to the shrimp at any stage of its development, preferably at a post-larval stage.

[0075] The yeast according to the invention can be administered into the water in which the shrimp are located, preferably into the water of the tank or pond. In particular, the yeast can be administered into the water either by direct administration of the yeast itself (according to a first variant described below) or by its prior incorporation into a food composition, said food composition being administered into the water (according to a second variant described below).

[0076] Yeast can be administered in water (regardless of the method of administration) in a quantity of 0.005 to 5 g / m³ 3 water, preferably from 0.01 to 2 g / m³ 3 of water, more preferably from 0.02 to 1 g / m³ 3 of water, for example from 0.005 to 0.01 g / m³ 3 of water, or 0.01 to 0.05 g / m³ 3 of water, or 0.05 to 0.1 g / m³ 3 of water, or 0.1 to 0.2 g / m³ 3 of water, or 0.2 to 0.3 g / m³ 3 of water, or 0.3 to 0.4 g / m³ 3 of water, or 0.4 to 0.5 g / m³ 3 of water, or 0.5 to 0.6 g / m³ 3 of water, or 0.6 to 0.7 g / m³ 3 of water, or 0.7 to 0.8 g / m³ 3 of water, or 0.8 to 0.9 g / m³ 3 of water, or 0.9 to 1 g / m³ 3 of water, or 1 to 1.5 g / m³ 3 of water, or 1.5 to 2 g / m³ 3 of water, or 2 to 5 g / m³ 3 of water.

[0077] Yeast administration can be occasional but is preferably repeated over time, over any suitable period (including throughout the shrimp's life).

[0078] In particular, the yeast according to the invention is administered daily. Preferably, the yeast is administered daily in the quantities indicated above. Thus, preferably, the yeast according to the invention is administered in water in an amount of 0.005 to 5 g / m³. 3 of water / day, preferably 0.01 to 2 g / m³ 3 water / day, preferably 0.02 to 1 g / m³ 3 of water / day.

[0079] Advantageously, the administered yeast concentration is 7.7 to 10.7 log CFU / m³ 3 of water / day, preferably 8 to 10.2 log CFU / m³ 3 water / day, preferably 9 to 10 log CFU / m³ 3 of water / day.

[0080] According to one variant, the yeast is added directly to the water, particularly in the quantities mentioned above. By "added / administered directly to the water" we mean that the yeast is added to the water alone, i.e. without mixing with, or adding to, other ingredients (other than water), the yeast can however be in all the forms described in the previous section (i.e. with any dry matter content), and may optionally have been concentrated or diluted before being added to the shrimp water.

[0081] Yeast added directly to water may optionally be suspended in a volume of water before that volume is added to the water containing the shrimp. In other embodiments, the yeast is added directly to the water containing the shrimp without prior suspension; in particular, the yeast may be added directly to the water containing the shrimp in dry form.

[0082] According to another embodiment, the yeast according to the invention can be administered in water (in particular in the quantities mentioned above) combined with one or more excipients, intended in particular to allow the yeast to be shaped into a given pharmaceutical form. These excipients can be of any suitable type.

[0083] Yeast administered according to one of the two variants above may be administered in water in any suitable pharmaceutical form. Yeast may, in particular, be formulated in liquid form, in lyophilized form, in the form of a tablet, a capsule, a granule, a gel, a powder, a microgranulated powder, in an effervescent form, for example in the form of an effervescent powder, in a form with gradual and / or controlled release, in a water-soluble sachet, preferably with controlled release, or in the form of mixtures of such forms.

[0084] According to another specific variant, the yeast can be incorporated into a food composition (i.e., a composition intended for feeding shrimp), said composition being administered to the shrimp. Preferably, the food composition is administered in the water in which the shrimp are located, preferably in the water of the tank or pond.

[0085] The food composition is preferably a solid composition.

[0086] The feed composition containing yeast may have any structure suitable for administration to shrimp. The yeast may be distributed homogeneously or unevenly throughout all or part of the feed composition. The yeast may be present in any part of the feed composition.

[0087] Advantageously, the food composition according to the invention comprises a coating layer surrounding a core, the yeast being present in the coating layer. In the context of the present invention, the term "core" or "peripheral" refers to the portion of the food composition covered by the coating layer; the core may have any shape, composition, and structure. According to the invention, the coating layer has a different composition from that of the core.

[0088] Preferably, the core of the food composition is shrimp food.

[0089] The yeast-coated feed according to the invention (i.e., the core of the feed composition) can be any feed commonly used in shrimp farming, these feeds being well known to those skilled in the art. It may, in particular, contain proteins, carbohydrates, fats, fibers, minerals, and / or vitamins.

[0090] More specifically, the core of the feed composition advantageously comprises fishmeal (for example, in an amount greater than or equal to 3% by mass, or greater than or equal to 5% by mass, or greater than or equal to 10% by mass, relative to the total mass of the core), and / or (preferably and) fish oil (for example, in an amount greater than or equal to 2% by mass, or greater than or equal to 4% by mass, relative to the total mass of the core). It may also comprise meal from at least one cephalopod, for example, squid meal; and / or one or more vegetable flours, in particular flour from at least one oilseed and / or flour from at least one cereal, for example, soybean flour and / or wheat flour.

[0091] The core of the food composition preferably comprises at least 25% by mass, preferably at least 30% by mass, and more preferably at least 35% by mass, of protein, relative to the total mass of the core, in particular 25 to 60% by mass, preferably 30 to 50% by mass, and more preferably 30 to 40% by mass, of protein. Advantageously, the core of the food composition comprises an amount of fat (or lipids) of 1 to 10% by mass, preferably 2 to 8% by mass, and more preferably 3 to 7% by mass, relative to the total mass of the core.

[0092] The coating layer may cover the entire surface of the core of the food composition or only a portion of it. Preferably, the coating layer covers the entire surface of the core (preferably, of the shrimp food).

[0093] Preferably, the core of the food composition is devoid of live yeast according to the invention (i.e., it does not contain live yeast according to the invention), or is essentially devoid of live yeast according to the invention. In particular, the core of the food composition preferably contains an amount of live yeast less than or equal to 10% by mass, more preferably less than or equal to 5% by mass, more preferably less than or equal to 2% by mass, more preferably less than or equal to 1% by mass, and even more preferably about 0% by mass, relative to the total mass of the core.

[0094] The coating layer may advantageously also include a fat. The fat may be an oil, particularly a vegetable or animal oil. The oil may be any suitable oil, such as rapeseed oil or fish oil. The fat, preferably oil, is preferably present in the coating layer in an amount of 0.5 to 5% by mass, more preferably 1 to 3% by mass, relative to the total mass of the nucleus in the food composition. The fat facilitates the formation of a yeast coating layer around the nucleus.

[0095] Advantageously, the food composition according to the invention is prepared by a process comprising mixing yeast with a fat (preferably as described above) and / or with water to form a coating composition, and then coating the core (preferably shrimp feed, more preferably shrimp feed in granular form) with the coating composition. Techniques for coating granules with an oil- and / or water-based composition are known to those skilled in the art.

[0096] In other embodiments, the yeast is not present in a coating layer of the feed composition but is present mixed with the basic ingredients of the shrimp feed (the feed composition may or may not include a coating layer). In these embodiments, the basic ingredients of the shrimp feed and their quantities may be as described above in relation to the composition of the core. In still other embodiments, the feed composition includes a coating layer, and the yeast is present in both the coating layer and the core of the feed composition. In these embodiments, in addition to the presence of the yeast, the composition of the core (i.e., its ingredients and their quantities) may be as described above.

[0097] Preferably, the food composition includes yeast (preferably in the coating layer) in an amount of 0.005 to 5% by mass, preferably 0.01 to 2% by mass, more preferably 0.02 to 1% by mass, even more preferably 0.05 to 0.5% by mass, relative to the total mass of the food composition. In embodiments, the food composition may comprise, relative to the total mass of the food composition, from 0.005 to 0.01% by mass, or from 0.01 to 0.05% by mass, or from 0.05 to 0.1% by mass, or from 0.1% to 0.15% by mass, or from 0.15 to 0.2% by mass, or from 0.2 to 0.25% by mass, or from 0.25 to 0.3% by mass, or from 0.3 to 0.35% by mass, or from 0.35 to 0.4% by mass, or from 0.4 to 0.45% by mass, or from 0.45 to 0.5% by mass, or from 0.5 to 0.7% by mass, or from 0.7 to 1% by mass, or from 1 to 2% by mass, or from 2 to 5% by mass of active yeast, preferably in the coating layer.

[0098] Advantageously, yeast is included in the food composition, preferably in the coating layer, in an amount of 5.4 to 8.4 log CFU (Colony Forming Units) / g of food composition, preferably 6 to 8 log CFU / g of food composition, more preferably 6.7 to 7.6 log CFU / g of food composition.

[0099] The feed composition according to the invention can be in any form suitable for feeding shrimp. In particular, it can be in a form such as mentioned above. Specifically, the feed composition can be in the form of granules or powder (in the latter embodiment, the powder comprises particles that are advantageously in the form of a core coated with a coating layer), preferably in the form of granules. Advantageously, the granules have a size ranging from 0.1 to 5 mm, preferably from 0.2 to 4 mm, and in particular from 0.3 to 3 mm.

[0100] Preferably, the food composition has a density greater than or equal to 500 kg / m³ 3 , preferably even greater than or equal to 600 kg / m 3 , more preferably greater than or equal to 650 kg / m 3 , for example from 500 to 1000 kg / m 3 , preferably 600 to 800 kg / m 3 , in particular from 650 to 750 kg / m 3 .

[0101] Preferably, the food composition has good stability in water (or "water retention"), preferably it has a stability in water (corresponding to the time during which the composition retains its physical integrity when placed in water) greater than or equal to 1 h, more preferably greater than or equal to 2 h.

[0102] In some embodiments, the food composition may further include probiotic bacteria (such as Bacillus megaterium, Paracoccus pantotrophus, Bacillus subtilis, Bacillus licheniformis, Bacillus pumilus, Bacillus amyloliquefaciens, Enterecoccus faecium, Thiobacillus denitrificans, or combinations thereof), preferably in the coating layer of the composition. In other embodiments, the food composition is devoid of one or more of the above-mentioned probiotic bacteria, or of all of the above-mentioned probiotic bacteria, and may more specifically be devoid of all probiotic bacteria.

[0103] In another aspect, the invention relates to a feed composition comprising a yeast as described above, for use in the treatment of white feces syndrome in shrimp. The feed composition may be as described above. The above description (particularly regarding the yeast used, the shrimp treated, the means of administration, etc.) applies similarly to this aspect of the invention.

[0104] In another aspect, the invention relates to the use of an active yeast of the genus Saccharomyces to treat (in particular to prevent, mitigate, and / or cure) white fecal syndrome (WFS) in shrimp. The above description (particularly regarding the yeast used, the shrimp treated, the means of administration, etc.) applies similarly to this aspect of the invention.

[0105] In yet another aspect, the invention relates to a method for treating white fecal syndrome (WFS) in shrimp, comprising a step of administering an active yeast of the genus Saccharomyces to the shrimp. The above description (particularly regarding the yeast used, the shrimp treated, the means of administration, etc.) applies similarly to this aspect of the invention.

[0106] Food composition

[0107] Another object of the invention consists of a food composition intended for feeding shrimp (or shrimp food composition) comprising an active yeast of the genus Saccharomyces.

[0108] The active yeast can be as described above.

[0109] The above description regarding the use of yeast in a feed composition for treating WFS (in particular, the description of the feed composition (its structure, composition, etc.) and the description of the shrimp for which it is intended) applies equally to this object of the invention. Specifically, the feed composition may comprise a core and a coating layer surrounding the core, the coating layer preferably comprising active yeast of the genus Saccharomyces.

[0110] The invention also relates to the use of a feed composition comprising at least one active yeast of the genus Saccharomyces for feeding shrimp. The feed composition, the yeast, and the shrimp intended to receive said feed composition may be as described above in relation to the other objects of the invention.

[0111] The invention also relates to a food composition as described above for its use as a medicine in shrimp.

[0112] Examples

[0113] The following examples illustrate the invention without limiting it.

[0114] Test conditions

[0115] The tests were carried out with juvenile (with a mass of approximately 1.0 g) Litopenaeus vannamei (white-legged shrimp) SPF (for "specific pathogen free") shrimp.

[0116] The shrimp were distributed among 20 tanks, each containing 250 L of seawater diluted with fresh water to achieve a salinity of 2%, with 60 shrimp per tank. The water temperature was maintained between approximately 28 and 30°C.

[0117] During the testing period, the shrimp were fed their respective diets four times a day, to satiety (the amount of food was adjusted according to the estimated biomass and the shrimp's behavior in the tanks). The shrimp were fed with commercially available Pro-Tom granulated shrimp food from the supplier DeHeus (hereafter referred to as the "basic food"), possibly modified as explained below.

[0118] The shrimp were divided into 4 groups, with 5 replicates (5 tanks) per group:

[0119] - group 1, forming a negative control: shrimp not infected and not supplemented with yeast;

[0120] - Group 2, forming a positive control: infected shrimp not supplemented with yeast; - Group 3: infected shrimp supplemented with yeast via direct administration into the pond water; and

[0121] - group 4: infected shrimp supplemented with yeast via administration through shrimp feed.

[0122] The yeast used for shrimp in groups 3 and 4 is an instant dry Saccharomyces cerevisiae yeast obtained by culturing the strain deposited at the CNCM on December 2, 2010 under number I-4407.

[0123] Test procedure

[0124] The tests were conducted over a period of 47 days. These tests comprised three phases:

[0125] - phase 1: pre-inoculation phase, lasting 21 days (from day 1 to day 21);

[0126] - Phase 2: Inoculation phase, lasting 10 days (from day 22 to day 31), itself divided into two sub-phases:

[0127] ■ EHP inoculation phase, over a period of 7 days (from day 22 to day 28);

[0128] ■ Vibrio inoculation phase, over a period of 3 days (from day 29 to day 31);

[0129] - Phase 3: Post-inoculation phase, lasting 16 days (from day 32 to day 47)

[0130] WFS Activation

[0131] Shrimp in groups 2, 3, and 4 underwent infection with Enterocytozoon hepatopenaei (EHP) to create intestinal lesions from day 22 to day 28, followed by infection with Vibrio alginolyticus from day 29 to day 31 to induce superinfection and dysbiosis of the digestive system, thereby triggering the onset of white feces syndrome. The induction of white feces syndrome by Enterocytozoon hepatopenaei infection followed by Vibrio infection is documented in the article "Experimental reproduction of White Feces Syndrome in whiteleg shrimp, Penaeus vannamei," LF Aranguren Caro et al., PLOS One, vol. 16, no. 12, 2021.

[0132] Infections by EHP and Vibrio alginolyticus were carried out via the shrimp's diet, by coating their food with these microorganisms.

[0133] EHP infection was carried out as follows: feces from EHP-infected shrimp (with an EHP load of approximately 10 8 -10 9 (copies / g) were mixed at a concentration of 3% by mass with 5% by mass of seawater (relative to the mass of the feed pellets to be coated), and the resulting suspension was then diluted 100-fold. The diluted suspension was applied to the base feed pellets to coat them with EHP. These pellets were used to feed shrimp in groups 2, 3, and 4 for 7 days, from day 22 to day 28 (referred to as the "EHP inoculation phase" in this text), during their second and fourth feedings of the day.

[0134] Infection with the bacterium Vibrio alginolyticus was carried out as follows: a culture broth containing a Vibrio alginolyticus density of approximately 10 9The culture broth was prepared from a Vibrio alginolyticus isolate collected from infected shrimp. The culture broth was then mixed with the base feed pellets in a 1:2 (v / m) ratio. The mixture was incubated for 2 hours at room temperature, and then a powdered binder (Nustic®, marketed by Bayer) was used at a rate of 3 g / kg of feed to fix the bacterial coating. These pellets were used to feed shrimp in groups 2, 3, and 4 for 3 days, from day 29 to day 31 (referred to as the "Vibrio inoculation phase" in this text), during their second and fourth feedings of the day.

[0135] Group 1 (negative control)

[0136] The shrimp in group 1 were fed:

[0137] - from day 1 to day 21 and from day 32 to day 47: through the staple food, during the four meals of the day, and

[0138] - from J22 to J31 (period corresponding to the phases of EHP inoculation and Vibrio inoculation in groups 2, 3 and 4): by the basic food coated with sterile tryptic soy broth (or TSB for "tryptic soy broth"), during the four meals of the day.

[0139] The coating of the granules with the tryptic soy broth was carried out in the same way as the coating with Vibrio bacteria described above.

[0140] Group 2 (positive control)

[0141] The shrimp in group 2 were fed:

[0142] - From day 1 to day 21 and from day 32 to day 47: through the staple food, during the four meals of the day.

[0143] - from J22 to J28: with food coated in tryptic soy broth during the first and third meals of the day and with food coated in EHP during the second and fourth meals of the day, and - from J29 to J31: with food coated in tryptic soy broth during the first and third meals of the day and with food coated in Vibrio during the second and fourth meals of the day.

[0144] Group 3

[0145] The shrimp in group 3 were fed:

[0146] - From day 1 to day 21 and from day 32 to day 47: through the staple food, during the four meals of the day.

[0147] - From day 22 to day 28: with food coated in triptych soy broth during the first and third meals of the day, and with food coated in EHP during the second and fourth meals of the day, and

[0148] - from J29 to J31: by the food coated with tryptic soy broth during the first and third meals of the day and by the food coated with Vibrio during the second and fourth meals of the day.

[0149] In addition, throughout the entire duration of the test (from day 1 to day 47), yeast was dispersed into the water of the shrimp tanks once a day, every day, in an amount of 0.5 g / m³ 3 of water (corresponding to a concentration of approximately 9.7 log CFU / m³) 3 of water).

[0150] Group 4

[0151] The shrimp in group 4 were fed a yeast-coated diet throughout the test.

[0152] The yeast-coated feeds were prepared according to the following protocol, per kg of feed: 2.5 g of yeast were mixed in 100 mL of potable water until the yeast was completely dissolved, then 20 g of rapeseed oil were added and the mixture was blended to form an emulsion. The emulsion was then deposited onto the base feed pellets, and the coated feeds were stored at room temperature. The feeds contain a yeast concentration of approximately 7.4 log CFU / g of feed.

[0153] The shrimp in group 4 were fed:

[0154] - From day 1 to day 21 and from day 32 to day 47: via the yeast-coated food, during the four meals of the day,

[0155] - from J22 to J28: by the yeast-coated food during the first and third meals of the day and by the EHP-coated food during the second and fourth meals of the day, and - from J29 to J31: by the yeast-coated food during the first and third meals of the day and by the Vibrio-coated food during the second and fourth meals of the day.

[0156] Results

[0157] At day 47, the average survival rate and average individual mass of the shrimp were measured for each of the four groups.

[0158] The average survival rate is expressed as a percentage relative to the initial number of shrimp in each tank. For each group, this rate was measured in each of the 5 tanks, and the average of the rates across the five tanks was calculated.

[0159] The average individual mass was measured as follows: for each group, 9 shrimp per tank were weighed, for the five tanks in the group, and the average mass of these shrimp was calculated.

[0160] The results (means and standard deviations) are presented in the following table:

[0161] Table 1 ]

[0162] In the table above, for each column (Mean individual mass and Mean survival rate), means marked with a different letter indicate a significant difference between said means (Tukey's DSH test, p < 0.05).

[0163] Survival rates after 47 days in shrimp receiving the active yeast were better than those in untreated, diseased shrimp (i.e., those fed only the control diet and infected). This improved survival was observed regardless of how the active yeast was administered, whether directly into the water or as an addition to the shrimp's diet. In the case of shrimp where the yeast was administered directly into the tank water, the survival rate was not significantly different from that of uninfected shrimp.

[0164] In addition, the shrimp that received the active yeast were significantly larger than the untreated, diseased shrimp.

Claims

Demands 1. Active yeast of the genus Saccharomyces for its use in the treatment of white feces syndrome (WFS) in shrimp.

2. Yeast for its use according to claim 1, wherein the treatment is a prophylactic treatment and / or a curative treatment.

3. Yeast for its use according to claim 1 or 2, selected from the group consisting of the species Saccharomyces cerevisiae, Saccharomyces cerevisiae var. boulardii, and mixtures thereof, preferably the yeast is of the species Saccharomyces cerevisiae.

4. Yeast for use according to any one of claims 1 to 3, obtained from a strain selected from the group consisting of the strain filed with the CNCM on December 2, 2010 under number I-4407, the strain filed with the CNCM on August 30, 2017 under number I-5223 and combinations thereof.

5. Yeast for its use according to any one of claims 1 to 4, said yeast being in the form of dry yeast.

6. Yeast for use according to any one of claims 1 to 5, wherein the shrimp is selected from the group consisting of white-legged shrimp, giant tiger shrimp and mixtures thereof.

7. Yeast for use according to any one of claims 1 to 6, wherein the shrimp is present in a tank comprising water, said yeast is administered into the water of the tank.

8. Yeast for use according to claim 7, wherein the yeast is administered into the basin water in a quantity of 0.005 to 5 g / m³ 3 of water / day, preferably 0.01 to 2 g / m³ 3 water / day, preferably 0.02 to 1 g / m³ 3 of water / day.

9. Yeast for use according to any one of claims 1 to 8, wherein said yeast is administered in a shrimp food composition.

10. Yeast for its use according to claim 9, wherein the composition comprises a core and a coating layer surrounding said core, the yeast being present in the coating layer.

11. Yeast for its use according to claim 9 or 10, wherein the yeast is included in the food composition in an amount of 0.005 to 5% by mass, preferably 0.01 to 2% by mass, more preferably 0.02 to 1% by mass, even more preferably 0.05 to 0.5% by mass, relative to the total mass of the food composition.

12. Yeast for use according to any one of claims 1 to 11, formulated in liquid form, in lyophilized form, in tablet form, in capsule form, in granule form, in gel form, in powder form, in microgranulated powder form, in effervescent form, in a form with gradual and / or controlled release, and / or in a water-soluble sachet.

13. Yeast for use according to any one of claims 1 to 12, wherein white fecal syndrome is caused by infection by at least one microorganism selected from fungi of the genus Enterocytozoon, preferably Enterocytozoon hepatopenaei, bacteria of the genus Vibrio, preferably Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio harveyi, Vibrio fluvialis, Vibrio vulnificus, Vibrio sinaloensis, Vibrio mimicus, Vibrio cholerae and / or Vibrio anguillarum, bacteria of the genus Propionigenium, bacteria of the genus Photobacterium, preferably Photobacterium damselae, gregarines and combinations thereof.

14. Shrimp food composition comprising at least one active yeast of the genus Saccharomyces, preferably of the species Saccharomyces cerevisiae, said composition preferably comprising a core and a coating layer surrounding said core, in which the coating layer comprises said at least one active yeast of the genus Saccharomyces.

15. Food composition according to claim 14, wherein the active yeast is obtained from a strain selected from the group consisting of the strain filed with the CNCM on December 2, 2010 under number I-4407, the strain filed with the CNCM on August 30, 2017 under number I-5223 and combinations thereof.

16. Food composition according to claim 14 or 15 for its use as a medicinal product in shrimp.

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