Use of yeast for the treatment of white fecal syndrome

Abstract

The invention relates to an active yeast of the genus Saccharomyces for use in the treatment of white fecal syndrome (WFS) in shrimp. The invention also relates to a shrimp feed composition comprising at least one active yeast of the genus Saccharomyces. No figure.

Description

Title of the invention: Use of yeast for the treatment of leukorrhea syndrome. Field of the invention

[0001] 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. Technical background

[0002] White Feces Syndrome (WFS) is an emerging disease affecting shrimp farms, particularly those of the Penaeidae family, 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, thus causing significant economic losses for farmers. This syndrome is also associated with reduced feed intake by affected shrimp, coupled with a deterioration in feed conversion ratio, increased size heterogeneity, the appearance of ultrastructural disorders in their hepatopancreas and intestines, associated with discoloration of these two organs and a soft carapace.

[0003] White feces syndrome has a complex etiology. It can have various, often multiple, causes that are not yet fully identified. It results from an alteration of the shrimp's intestinal microbiota, which can be caused, promoted, or aggravated by, in particular, a fungal infection (especially by Enterocytozoon hepatopenaei (EHP)) and / or a bacterial infection (especially by Vibrio and / or Propionigenium), poor-quality feed containing antinutritional factors or mycotoxins, and the presence of algal toxins and / or gregarins.

[0004] 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 shrimp.

[0005] There is a real need to develop a means of treating white feces syndrome in shrimp that is effective, economical, and easy to implement. Summary of the invention

[0006] The invention relates primarily to an active yeast of the genus Saccharomyces for its use in the treatment of white fecal syndrome (WFS) in shrimp.

[0007] In some embodiments, the treatment is a prophylactic treatment and / or a curative treatment.

[0008] In 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.

[0009] In 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 1-4407, the strain filed with the CNCM on August 30, 2017 under number 1-5223 and combinations thereof.

[0010] In some embodiments, said yeast is in the form of dry yeast.

[0011] In some embodiments, the shrimp is chosen from the group consisting of the white-legged shrimp, giant tiger prawn and mixtures thereof.

[0012] In embodiments, the shrimp is present in a basin containing water, and said yeast is administered into the water of the basin.

[0013] In embodiments, the yeast is administered in the basin water in an amount of 0.005 to 5 g / m3 of water / day, preferably 0.01 to 2 g / m3 of water / day, more preferably 0.02 to 1 g / m3 of water / day.

[0014] In embodiments, said yeast is administered in a shrimp food composition.

[0015] In embodiments, the composition comprises a core and a coating layer surrounding said core, the yeast being present in the coating layer.

[0016] In 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, even more preferably 0.05 to 0.5% by mass, relative to the total mass of the food composition.

[0017] 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 a form with gradual and / or controlled release, and / or in a water-soluble sachet.

[0018] 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.

[0019] 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.

[0020] In 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 1-4407, the strain filed with the CNCM on August 30, 2017 under number 1-5223 and combinations thereof.

[0021] The present invention addresses the need expressed above. More specifically, it provides an effective preventive 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.

[0022] This is achieved through the use of a live (or active) yeast of the genus Saccharomyces. It has been surprisingly discovered that administering such a yeast to shrimp prevents the onset of the disease and also reduces the symptoms of the syndrome in shrimp affected by the disease. In particular, 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 disparities between shrimp. Detailed description

[0023] The invention is now described in more detail and in a non-limiting manner in the following description.

[0024] In this text, unless expressly stated otherwise, all percentages (%) indicated are percentages by mass.

[0025] 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.

[0026] The invention relates primarily to a yeast for use in the treatment of white feces syndrome in shrimp. For the purposes of the present invention, "treatment" includes both prophylactic treatments than curative treatments. Thus, the yeast according to the invention can be used to prevent white fecal syndrome and / or to cure or alleviate white fecal syndrome.

[0027] Preferably, the treatment according to the invention results in an increase in the survival rate of the shrimp, compared to untreated shrimp.

[0028] Preferably, the treatment according to the invention results in an increase in the individual mass of the shrimp, compared to untreated shrimp.

[0029] Preferably, the treatment according to the invention results in a decrease in the feed conversion ratio in shrimp, compared to untreated shrimp.

[0030] Preferably, the treatment according to the invention results in a reduction of the disparities in size / mass between the shrimp (or, in other words, results in an increase in the homogeneity of the sizes / mass of the shrimp), compared to untreated shrimp.

[0031] 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. Yeast

[0032] 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).

[0033] The yeast according to the invention is a yeast belonging to the genus Saccharomyces. As yeast which can be used according to the invention, mention may be made of yeasts of 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.

[0034] More particularly, the yeast is chosen from the species Saccharomyces cerevisiae, Saccharomyces cerevisiae var. boulardii and combinations thereof.

[0035] Preferably, the yeast according to the invention is a Saccharomyces cerevisiae yeast.

[0036] 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 1-4407, 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 1-5222, the stub filed with the CNCM on August 30, 2017 under number 1-5223 and combinations thereof.

[0037] More 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 1-4407, the strain filed with the CNCM on August 30, 2017 under number 1-5223, and combinations thereof.

[0038] 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.

[0039] The appropriate culture medium and culture 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 TW Nagodawithana, 2nd edition, 1991 (ISBN 0-442-31892-8).

[0040] The yeast according to the invention may 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 may, 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.

[0041] By "fresh yeast", we preferably mean yeast having a dry matter content of less than 50% by mass. Fresh yeast can 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).

[0042] By "intermediate moisture yeast," one preferably means 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.

[0043] Preferably, the yeast is a dry yeast. A dry yeast has the advantage of having a longer shelf life.

[0044] The dry yeast according to the invention may in particular be an active dry yeast or an instant active dry yeast.

[0045] The active dry yeast or instant active dry yeast according to the invention comprises a yeast dry matter content greater than 90% by mass, preferably a dry matter content of 92% to 96% by mass.

[0046] 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, active dry yeast can be obtained by extrusion and fluidized bed drying of pressed or liquid yeast.

[0047] The active dry yeast according to the invention can in particular be prepared by a process comprising the following steps: - 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; - 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; - mixing liquid yeast cream or liquid yeast with a brine, in particular a brine based on sodium chloride; - dehydration of the mixture to obtain dehydrated yeast; - extrusion of dehydrated yeast to obtain extruded yeast; - drying of the extruded yeast to obtain dry yeast.

[0048] The active dry yeast is preferably in the form of spherules, the diameter of which is preferably from 0.1 mm to 2.5 mm, and preferably having a water content of 4% to 8% by mass.

[0049] Instant active dry yeast has the advantage 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 strands (while remaining active). The instant dry yeast is preferably then packaged in the absence of oxygen to ensure its stability.

[0050] The yeast according to the invention can be presented in any suitable form, in particular in the forms described above (in particular in the form of spherules, or vermicelli).

[0051] The yeast according to the invention may be an active yeast adapted to weak organic acids. By "active yeast adapted to weak organic acids," we mean 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 These reactions are not inhibited when the yeast is exposed to a weak organic acid for at least the second time. "Weak organic acids" refers to organic acids themselves and their salts. Preferably, the weak organic acids are selected 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. WFS processing

[0052] By "white feces syndrome" is conventionally understood to mean diseases characterized by the production by the shrimp of white fecal filaments floating in the water.

[0053] 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.

[0054] In embodiments, the white feces syndrome treated according to the invention is caused in the shrimp by an infection by at least one fungus of the genus Enterocytozoon, preferably by at least Enterocytozoon hepatopenaei.

[0055] In 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 parahaemolytiens, Vibrio alginolytiens, Vibrio harveyi, Vibrio fluvialis, Vibrio vulnificus, Vibrio sinaloensis, Vibrio mimicus, Vibrio cholerae, Vibrio anguillarum and combinations thereof.

[0056] 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 Propionigenium.

[0057] In embodiments, the white feces syndrome treated according to the invention is caused in the shrimp by an infection by at least one bacterium of the genus Photobacterium, such as Photobacterium damselae.

[0058] In embodiments, the white feces syndrome treated according to the invention is caused in the shrimp by an infection with at least one gregarin.

[0059] The white fecal syndrome treated according to the invention can in particular be caused by a co-infection by two or more of the microorganisms mentioned above, for example by a co-infection by at least one fungus of the genus Enterocytozoon and A 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.

[0060] 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.

[0061] Preferably, the shrimp treated is a shrimp of the suborder Dendrobranchiata, more preferably of the family Penaeidae, and even more preferably of the genus Penaeus, for example chosen from the white-legged shrimp (Eitopenaeus 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.

[0062] Even more preferably, the shrimp treated according to the invention is chosen from the group consisting of the white-legged shrimp (Eitopenaeus vannamei, also known as Penaeus vannamei), the giant tiger shrimp (Penaeus monodon) and mixtures thereof.

[0063] Advantageously, the shrimp treated according to the invention is a farmed shrimp.

[0064] Preferably, the treated shrimp is present in a basin or pond filled with water (this water can be salt water or fresh water, preferably salt water).

[0065] The yeast according to the invention can be administered to the shrimp at any stage of its development, preferably at a post-larval stage.

[0066] The yeast according to the invention can be administered into the water in which the shrimp is located, preferably into the water of the tank or pond. In particular, the yeast can be administered into the water via direct administration of the yeast itself (according to a first embodiment described below) or via its prior incorporation into a food composition, said food composition being administered into the water (according to a second embodiment described below).

[0067] Yeast can in particular be administered in water (regardless of the method of administration) in an amount of 0.005 to 5 g / m3 of water, preferably 0.01 to 2 g / m3 of water, more preferably 0.02 to 1 g / m3 of water, for example 0.005 to 0.01 g / m3 of water, or 0.01 to 0.05 g / m3 of water, or 0.05 to 0.1 g / m3 of water, or 0.1 to 0.2 g / m3 of water, or 0.2 to 0.3 g / m3 of water, or 0.3 to 0.4 g / m3 of water, or 0.4 to 0.5 g / m3 of water, or 0.5 to 0.6 g / m3 of water, or 0.6 to 0.7 g / m3 of water, or 0.7 to 0.8 g / m3 of water, or 0.8 to 0.9 g / m3 of water, or 0.9 to 1 g / m3 of water, or 1 to 1.5 g / m3 of water, or 1.5 to 2 g / m3 of water, or 2 to 5 g / m3 of water.

[0068] Yeast administration can be occasional but is preferably repeated over time, over any suitable period (including throughout the life of the shrimp).

[0069] 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 of water / day, preferably 0.01 to 2 g / m3 of water / day, more preferably 0.02 to 1 g / m3 of water / day.

[0070] Advantageously, the administered yeast concentration is 7.7 to 10.7 log CFU / m3 of water / day, preferably 8 to 10.2 log CFU / m3 of water / day, more preferably 9 to 10 log CFU / m3 of water / day.

[0071] According to a first embodiment, the yeast is added directly to the water, in particular in the quantities mentioned above. By "added / administered directly to the water" is meant that the yeast is added to the water alone, i.e. without mixing with, or addition to, other ingredients (other than water), the yeast being however in all the forms described in the preceding section (i.e. with any dry matter content), and optionally being able to have been concentrated or diluted before its addition to the shrimp water.

[0072] The yeast added directly to the water may optionally be suspended in a volume of water before said volume of water is added to the water in which the shrimp are present. In other embodiments, the yeast is added directly to the water in which the shrimp are present without prior suspension; in particular, the yeast may be added directly to the water in which the shrimp are present in dry form.

[0073] 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.

[0074] The yeast administered according to one of the two variants above can be administered in water in any suitable pharmaceutical form. The yeast can 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.

[0075] According to another particular embodiment, 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.

[0076] The food composition is preferably a solid composition.

[0077] The feed composition including the yeast may have any structure suitable for administration to shrimp. The yeast may be distributed homogeneously or non-homogeneously throughout all or part of the feed composition. The yeast may be present in any part of the feed composition.

[0078] 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" means the portion of the food composition covered by the coating layer; the core may have any shape, composition, and structure.

[0079] Preferably, the core of the food composition is shrimp food.

[0080] The yeast-coated feed according to the invention can be any feed commonly used in shrimp farming, these feeds being well known to those skilled in the art. In particular, it can contain proteins, carbohydrates, fats, fibers, minerals and / or vitamins.

[0081] The coating layer may cover the entire surface of the core of the food composition or only a portion of the core surface. Preferably, the coating layer covers the entire surface of the core (preferably, of the shrimp food).

[0082] The coating layer may advantageously further comprise a fat. The fat may, in particular, be an oil, especially a vegetable or animal oil. The oil may be any suitable oil, such as rapeseed oil or fish oil. The fat, preferably the 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 of the food composition. The fat facilitates the formation of a yeast coating layer around the nucleus.

[0083] Advantageously, the food composition according to the invention is prepared by a process comprising mixing the yeast with a fat (preferably as described above) and / or with water to form a coating composition, then coating the core (preferably shrimp feed, more preferably shrimp feed in pellet form) with the composition Coating. The techniques for coating granules with an oil and / or water-based composition are known to those skilled in the art.

[0084] In other embodiments, the yeast is not present in a coating layer of the food composition but is present mixed with the basic ingredients of the shrimp food (the food composition may or may not include a coating layer). In still other embodiments, the food composition includes a coating layer and the yeast is present in the coating layer and in the core of the food composition.

[0085] 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.

[0086] Advantageously, the 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.

[0087] The food 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 food composition can be in the form of granules or powder (in the latter embodiment, the powder comprises particles which are advantageously in the form of a core coated with a coating layer), preferably in the form of granules.

[0088] 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 bacteria probiotics mentioned above, or of all the probiotic bacteria mentioned above, and may more specifically be devoid of all probiotic bacteria.

[0089] According to another aspect, the invention relates to a food composition comprising a yeast as described above, for use in the treatment of white feces syndrome in shrimp. The food composition may be as described above. What has been described above (particularly concerning the yeast used, the shrimp treated, the means of administration, etc.) can be similarly applied to this aspect of the invention.

[0090] According to 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. What has been described above (particularly concerning the yeast used, the shrimp treated, the means of administration, etc.) can be similarly applied to this aspect of the invention.

[0091] According to 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. What has been described above (particularly concerning the yeast used, the shrimp treated, the means of administration, etc.) can be similarly applied to this aspect of the invention. Food composition

[0092] 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.

[0093] The active yeast may be as described above.

[0094] What has been described above in relation to the use of yeast in a food composition for the treatment of WFS (in particular, the description of the food composition and the description of the shrimp for which it is intended) applies in the same way to this object of the invention.

[0095] The invention also relates to a food composition as described above for its use as a medicine in shrimp. Examples

[0096] The following examples illustrate the invention without limiting it. Test conditions

[0097] The tests were carried out with juvenile (with a mass of about 1.0 g) Litopenaeus vannamei (white-legged shrimp) SPF (for "specific pathogen free").

[0098] 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.

[0099] During the testing period, the shrimp were fed their respective diets four times a day, to satiety (the amount of food being adjusted according to the estimated biomass and the behavior of the shrimp in the tanks). The shrimp were fed with commercially available granulated shrimp food marketed under the name Pro-Tom, from the supplier DeHeus (hereafter referred to as the "basic food"), possibly modified as explained below.

[0100] The shrimp were divided into 4 groups, with 5 replicates (5 tanks) per group: - group 1, forming a negative control: shrimp not infected and not supplemented with yeast; - group 2, forming a positive control: infected shrimp not supplemented with yeast; - Group 3: infected shrimp supplemented with yeast via direct administration into the water of the tanks; and - group 4: infected shrimp supplemented with yeast via administration through shrimp feed.

[0101] The yeast used for shrimp in groups 3 and 4 is an instant dry Saccharomyces cerevisiae yeast obtained by culture of the strain filed with the CNCM on December 2, 2010 under number 1-4407. Test procedure

[0102] The tests were conducted over a period of 47 days. These tests comprise three phases: - phase 1: pre-inoculation phase, lasting 21 days (from day 1 to day 21); - Phase 2: Inoculation phase, lasting 10 days (from day 22 to day 31), it- even divided into two sub-phases: • EHP inoculation phase, over a period of 7 days (from day 22 to day 28); • Vibriez inoculation phase over a period of 3 days (from day 29 to day 31); - Phase 3: Post-inoculation phase, lasting 16 days (from day 32 to day 47). WFS initiation.

[0103] Shrimp from groups 2, 3 and 4 underwent infection with Enterocytozoon hepatopenaei (EHP) to create intestinal lesions, from day 22 to day 28, then infection with Vibrio alginolyticus to cause superinfection and dysbiosis of the digestive system, from day 29 to day 31, so as to trigger the onset of fecal syndrome whites. The induction of white feces syndrome by infection with Enterocytozoon hepatopenaei followed by infection with a Vibrio bacterium 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, n°12, 2021.

[0104] Infections by EHP and by Vibrio alginolyticus were carried out via the feeding of the shrimp, by coating their food with these microorganisms.

[0105] EHP infection was carried out as follows: feces from EHP-infected shrimp (with an EHP load of approximately 10⁸–10⁹ copies / g) were mixed at a ratio 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.

[0106] Infection with the bacterium Vibrio alginolyticus was carried out as follows: a culture broth containing a Vibrio alginolyticus density of approximately 10⁹ CFU / mL 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 binder in powder form (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. Group 1 (negative control)

[0107] The shrimp in group 1 were fed: - 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 - 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.

[0108] 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. Group 2 (positive control)

[0109] The shrimp in group 2 were fed: - From day 1 to day 21 and from day 32 to day 47: through the staple food, during the four meals of the day. - 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 - 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. Group 3

[0110] The shrimp in group 3 were fed: - From day 1 to day 21 and from day 32 to day 47: through the staple food, during the four meals of the day. - 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 - 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.

[0111] In addition, throughout the duration of the test (from day 1 to day 47), yeast was dispersed in the shrimp tank water once a day, every day, at a rate of 0.5 g / m³ of water (corresponding to a concentration of approximately 9.7 log CFU / m³ of water). Group 4

[0112] The shrimp in group 4 were fed a yeast-coated diet throughout the duration of the test.

[0113] The yeast-coated foods were prepared by the following protocol, for For 1 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 feed was stored at room temperature. The feed contains a yeast concentration of approximately 7.4 log CFU / g of feed.

[0114] The shrimp in group 4 were fed: - 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, - From day 22 to day 28: with yeast-coated feed during the first and third meals of the day, and with EHP-coated feed during the second and fourth meals of the day, and - from day 29 to day 31: 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. Results

[0115] At J47, the mean survival rate and mean individual mass of the shrimp were measured for each of the four groups.

[0116] 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.

[0117] 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.

[0118] The results (means and standard deviations) are presented in the following table:

[0119] [Tables 1] Tested Group Mean Individual Mass at Day 47 (g) Mean Survival Rate at Day 47 (%) Group 1 (negative control) 13.2 ± 0.2a 78.8 ± 4.T Group 2 (positive control) 10.3 ± 0.3e 52.2 ± 7.5e Group 3 11.4 ± 0.7b 71.4 ± 3.3b Group 4 12.0 ± 0.7b 62.4 ± 2.6b

[0120] 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).

[0121] It was observed that the survival rates after 47 days in shrimp receiving the active yeast were better than those achieved in untreated sick shrimp (i.e., 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 by adding it to the shrimp's diet. In the case of shrimp in which the yeast was administered directly into the water in the tanks, the survival rate was not significantly different from that of uninfected shrimp.

[0122] In addition, the shrimp that received the active yeast are significantly larger than the untreated sick 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 1-4407, the strain filed with the CNCM on August 30, 2017 under number 1-5223 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 whiteleg shrimp, giant tiger prawn, and mixtures thereof.

7. Cl. Yeast for its 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 its use according to any one of claims 1 to 7, wherein said yeast is administered in a shrimp food composition.

9. Yeast for its use according to claim 8, wherein the composition comprises a core and a coating layer surrounding said core, the yeast being present in the coating layer.

10. Yeast for its use according to claim 8 or 9, 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.

11. Yeast for use according to any one of claims 1 to 10, 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.

12. Yeast for use according to any one of claims 1 to 11, wherein 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.

13. 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, wherein the coating layer comprises said at least one active yeast of the genus Saccharomyces.

14. Food composition according to claim 13, 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 1-4407, the strain filed with the CNCM on August 30, 2017 under number 1-5223 and combinations thereof.