Compound micromolecule coral food and application thereof in adjusting structure of coral symbiotic microbial community

Abstract

The application discloses a kind of complex small molecule coral food and its application in adjusting coral symbiotic microbial community structure.The raw materials of the complex small molecule coral food include: soybean meal small peptide protein, cod small peptide protein, haematococcus pluvialis powder, complex amino acid, squid meal, chitosan oligosaccharide and complex nucleotide.The complex small molecule coral food of the application takes soybean meal small peptide protein and cod small peptide protein as main component, haematococcus pluvialis as secondary component, and is supplemented with complex amino acid and squid meal, and is additionally added with chitosan oligosaccharide and complex nucleotide.The obtained complex small molecule coral food not only has good palatability, but also ensures the feeding amount of coral.It is verified by test that the complex small molecule coral food of the application can adjust the symbiotic microbial community structure of aquarium coral, improve the proportion of coral beneficial symbiotic bacteria, and further improve the environmental tolerance of coral.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, and more specifically, to a composite small molecule coral food and its application in adjusting the structure of coral symbiotic microbial communities. Background Technology

[0002] Corals are pleiotrophic organisms, relying on photosynthetic autotrophy and heterotrophy derived from symbiotic algae. When the symbiotic relationship is impaired, the coral receives less photosynthetic products from the symbiotic algae, making it prone to polyp shrinkage, tissue loss, and even bleaching. In this situation, heterotrophy becomes relatively more important. Heterotrophy has been shown to improve bleaching recovery and increase coral protein levels, chlorophyll concentration, photosynthetic rate, and growth rate.

[0003] In recent years, live soft corals have gained an increasingly larger share of the commercial aquarium market due to their thick, soft, and elastic polyps, vibrant and rich colors, and moderate difficulty in keeping them. However, corals in the aquarium market exist in a relatively stable and favorable environment (e.g., good water quality, suitable water temperature, and ample light), allowing them to grow and even reproduce naturally. But after packaging, transportation, and other processes, the corals' condition is easily affected, significantly diminishing their aesthetic appeal and even impacting their survival rate. At this point, relying solely on symbiotic algae for self-sufficiency is insufficient to meet the corals' nutritional needs, necessitating artificial feeding. Currently, live food such as zooplankton, rotifers, brine shrimp and their eggs, and microalgae, or their powdered mixtures, are used as the main nutritional sources. However, live food is difficult to store, grows at low densities, and when corals are in poor physiological condition, their polyps shrink, inhibiting predation behavior and resulting in low utilization rates of live food. Simply crushing live bait into powder requires multiple digestive steps before it can be absorbed due to its large molecular weight. This not only affects the coral's ability to eat but also impacts water quality, leading to excessive inorganic salt concentrations, water quality deterioration, and ultimately, the proliferation of pathogenic microorganisms.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a composite small molecule coral food and its application in adjusting the structure of coral symbiotic microbial communities. This composite small molecule coral food can improve the growth rate of artificially cultivated corals in the aquarium market and can adjust the structure of the symbiotic microbial community of corals in the aquarium market.

[0006] This invention is implemented as follows:

[0007] In a first aspect, the present invention provides a compound small molecule coral food, the raw materials of which include: soybean meal small peptide protein, cod small peptide protein, Haematococcus pluvialis powder, compound amino acids, squid powder, chitosan oligosaccharide and compound nucleotides.

[0008] In some embodiments, chitosan oligosaccharides and complex nucleotides account for 5-10% of the total mass of the complex small molecule coral food.

[0009] In some embodiments, the raw materials of the compound small molecule coral food include, by weight parts:

[0010] 30-50 parts soybean meal small peptide protein, 20-35 parts cod small peptide protein, 10-15 parts Haematococcus pluvialis powder, 3-5 parts compound amino acids, 2-5 parts squid powder, 5-10 parts chitosan oligosaccharide, and 3-5 parts compound nucleotides.

[0011] Secondly, the present invention provides a method for preparing the above-mentioned composite small molecule coral food, which includes: mixing soybean meal small peptide protein, cod small peptide protein, Haematococcus pluvialis powder, compound amino acids, squid powder, chitosan oligosaccharide and compound nucleotides in proportion, then pulverizing and sieving, and then heating and drying the sieved powder to obtain the composite small molecule coral food.

[0012] In some embodiments, the sieve mesh size is 160-200 mesh.

[0013] In some embodiments, the moisture content of the dried composite small molecule coral food is ≤10%.

[0014] Thirdly, this invention provides the application of the above-mentioned composite small molecule coral food in adjusting the structure of coral symbiotic microbial communities.

[0015] In some embodiments, the corals described above include torch corals.

[0016] In some embodiments, the above-mentioned adjustment of coral symbiotic microbial community structure includes reducing bacterial α diversity and species richness, increasing fungal α diversity and species richness, increasing the abundance of stress-resistant microorganisms, and reducing the abundance of pathogenic microorganisms.

[0017] In some embodiments, the above application includes adding compound small molecule coral food to an aquarium for cultivation, wherein the addition ratio of compound small molecule coral food in the aquarium is 0.005-0.02 g / L.

[0018] The present invention has the following beneficial effects:

[0019] The compound small-molecule coral food of this invention uses soybean meal peptide protein and cod peptide protein as the main components, Haematococcus pluvialis as the secondary component, supplemented with compound amino acids and squid powder, and further fortified with chitosan oligosaccharides and compound nucleotides. The resulting compound small-molecule coral food not only has good palatability and ensures adequate food intake for corals, but also, through experimental verification, can adjust the symbiotic microbial community structure of aquarium corals, increase the proportion of beneficial symbiotic bacteria, and thus improve the corals' environmental tolerance. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The Venn diagram for Experiment 1 is used to show the common and unique microorganisms of coral symbiotic bacteria in the feeding group FD and the control group CK;

[0022] Figure 2 The Chao1 index in Experiment 1 was used to compare bacterial α-diversity between the FD feeding group and the CK control group.

[0023] Figure 3 The Shannon index in Experiment 1 was used to compare bacterial α-diversity between the FD feeding group and the CK control group;

[0024] Figure 4 The nonmetric multidimensional scaling (NMDS) plot for Experiment Example 1 is used to show the corresponding stress values ​​at the OTU level between the FD group and the CK control group;

[0025] Figure 5 The community structure at the phylum level of coral symbiotic bacteria in Experiment Example 1 was used to compare the bacterial community composition of the feeding group FD and the control group CK.

[0026] Figure 6 The community structure at the order of coral symbiotic bacteria in Experiment 1 was used to compare the bacterial community composition of the feeding group FD and the control group CK.

[0027] Figure 7 The community structure of coral symbiotic bacteria resistant to oxidative stress in Experiment 1 was used to compare the bacterial community composition of the feeding group FD and the control group CK.

[0028] Figure 8 The community structure of Gram-negative bacteria in coral symbiotic bacteria in Experiment Example 1 was used to compare the bacterial community composition of the feeding group FD and the control group CK.

[0029] Figure 9 The Venn diagram for Experiment 1 is used to show the common and unique microorganisms of coral symbiotic fungi in the feeding group FD and the control group CK;

[0030] Figure 10 The Chao1 index in Experiment 1 was used to compare fungal α-diversity between the FD feeding group and the CK control group;

[0031] Figure 11 The Shannon index in Experiment 1 was used to compare fungal α-diversity between the FD feeding group and the CK control group;

[0032] Figure 12 The nonmetric multidimensional scaling (NMDS) plot for Experiment Example 1 is used to show the corresponding stress values ​​at the OTU level between the FD group and the CK control group;

[0033] Figure 13 The community structure at the phylum level of coral symbiotic fungi in Experiment Example 1 was used to compare the fungal community composition of the feeding group FD and the control group CK.

[0034] Figure 14 The community structure at the order of coral symbiotic fungi in Experiment 1 was used to compare the fungal community composition of the feeding group FD and the control group CK.

[0035] Figure 15 The community structure predicted by the surface of coral symbiotic fungi in Experiment 1 was used to compare the fungal community composition of the feeding group FD and the control group CK. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0037] The components of the compound small molecule coral food in this invention include: soybean meal small peptide protein, cod small peptide protein, Haematococcus pluvialis powder, compound amino acids, squid powder, chitosan oligosaccharide and compound nucleotides.

[0038] Among them, soybean meal small peptide protein, through microbial fermentation, maximizes the elimination of anti-nutritional factors in soybean meal, effectively degrades soybean protein into a high-quality small peptide protein source, and can produce active substances such as probiotics, oligopeptides, glutamic acid, lactic acid, vitamins, and UGF (unknown growth factor). It has the effects of improving palatability, improving nutrient digestion and absorption, promoting growth, and reducing diarrhea.

[0039] Cod small peptide protein uses fish scales or skin as raw materials. Large protein molecules are enzymatically hydrolyzed into high-purity collagen peptides with low molecular weight that can be completely absorbed by corals, thus further enhancing their nutritional and functional properties. Collagen peptides can efficiently synthesize collagen within the coral's body. Collagen is a major component in maintaining the morphology and structure of its intestines and organs, and is also an important raw material for repairing damaged tissues.

[0040] Haematococcus pluvialis is rich in protein and astaxanthin, and has the highest natural astaxanthin content among organisms. Astaxanthin not only has strong antioxidant activity but is also one of the most promising antioxidant pigments in nature. When applied to coral farming, it can improve the antioxidant capacity of corals and enhance their immunity.

[0041] As a nutritional enhancer, compound amino acids can replenish the 20% of the most effective nutrients lost during fishmeal processing, or supplement the incomplete amino acids in fishmeal that is not processed from whole fish. It contains a variety of essential amino acids that are essential for animals, and can supplement various essential amino acids, especially those that are easily lacking in conventional feed ingredients and plant feeds. By utilizing the principle of the balanced "barrel effect", it can enhance the effects of other nutrients.

[0042] Squid meal is a common aquatic attractant that can increase feed intake in animals. Chitosan oligosaccharides are known to promote absorption, improving the conversion rate of coral food. They are also rich in antibacterial active ingredients, enhancing coral immunity and resistance to pathogens. Furthermore, chitosan oligosaccharides have adsorption capacity, removing pollutants from the water and improving water quality stability and cleanliness. Complex nucleotides can promote coral gut growth and development, as well as the proliferation of beneficial gut microbiota, and also improve coral tolerance to environmental changes.

[0043] The composite small molecule coral food of the present invention was obtained by rationally combining the above components. The composite small molecule coral food has a small molecular weight and is easy to absorb. It has a relatively comprehensive nutritional composition, good nutritional balance, and is non-toxic and harmless. It can overcome the problem of insufficient absorption and utilization of existing coral food. At the same time, the composite small molecule coral food can also adjust the structure of coral symbiotic microbial community, including adjusting the diversity and species richness of bacteria and fungi, increasing the abundance of stress-resistant microorganisms, and reducing the abundance of pathogenic microorganisms.

[0044] Example 1

[0045] This embodiment provides a compound small molecule coral food, the raw materials of which include the following components in parts by weight: 40 parts soybean meal small peptide protein, 35 parts cod small peptide protein, 12 parts Haematococcus pluvialis powder, 5 parts compound amino acids, 3 parts squid powder, 5 parts chitosan oligosaccharide, and 5 parts compound nucleotides.

[0046] The preparation method of the composite small molecule coral food in this embodiment includes the following steps:

[0047] Soybean meal small peptide protein, cod small peptide protein, Haematococcus pluvialis powder, compound amino acids, squid powder, chitosan oligosaccharide and compound nucleotides were weighed and mixed according to the formula, pulverized and screened through a 160-200 mesh sieve, and the screened product was heated and dried to obtain compound small molecule coral food with a moisture content ≤10%.

[0048] Example 2

[0049] This embodiment provides a composite small molecule coral food. The specific preparation method is the same as in Example 1, except that the raw material composition of the composite small molecule coral food is different. The specific raw material composition is as follows:

[0050] 45 parts soybean meal small peptide protein, 25 parts cod small peptide protein, 15 parts Haematococcus pluvialis powder, 5 parts compound amino acids, 5 parts squid powder, 5 parts chitosan oligosaccharide, and 3 parts compound nucleotides.

[0051] Example 3

[0052] This embodiment provides a composite small molecule coral food. The specific preparation method is the same as in Example 1, except that the raw material composition of the composite small molecule coral food is different. The specific raw material composition is as follows:

[0053] 45 parts soybean meal small peptide protein, 25 parts cod small peptide protein, 10 parts Haematococcus pluvialis powder, 7 parts compound amino acids, 5 parts squid powder, 8 parts chitosan oligosaccharide, and 4 parts compound nucleotides.

[0054] Example 4

[0055] This embodiment provides a composite small molecule coral food. The specific preparation method is the same as in Example 1, except that the raw material composition of the composite small molecule coral food is different. The specific raw material composition is as follows:

[0056] 43 parts soybean meal small peptide protein, 23 parts cod small peptide protein, 15 parts Haematococcus pluvialis powder, 5 parts compound amino acids, 7 parts squid powder, 7 parts chitosan oligosaccharide, and 4 parts compound nucleotides.

[0057] Example 5

[0058] This embodiment provides a composite small molecule coral food. The specific preparation method is the same as in Example 1, except that the raw material composition of the composite small molecule coral food is different. The specific raw material composition is as follows:

[0059] 48 parts soybean meal small peptide protein, 20 parts cod small peptide protein, 15 parts Haematococcus pluvialis powder, 7 parts compound amino acids, 5 parts squid powder, 5 parts chitosan oligosaccharide, and 4 parts compound nucleotides.

[0060] Comparative Example 1

[0061] The difference from Example 1 is that no feeding measures are taken for the corals.

[0062] Experimental Example 1

[0063] The compound small molecule coral food from Example 1 was used for coral husbandry and management, and the adjustment of the coral symbiotic microbial community was verified. The steps are as follows:

[0064] I. Feeding and Management

[0065] 1. Test subject: The test coral was the torch coral.

[0066] 2. Experimental Environment: The corals were cultured in aquariums measuring 55cm × 55cm × 45cm. Two aquariums were used, with six corals in each tank. Before the formal experiment, the corals were acclimatized to the culture environment for two weeks. Healthy corals were then selected as test specimens and grouped for the experiment according to the requirements.

[0067] 3. Experimental groups: The corals were artificially fed with the compound small molecule coral food described in this invention for 30 days (experimental group FD), and compared with the same species of artificially cultured corals that grew naturally in the same water environment without added food (control group CK).

[0068] 4. Cultivation cycle: The cultivation cycle is 30 days, during which 20% of the water is changed every 7 days.

[0069] 5. DNA Extraction from Coral Symbiotic Microorganisms: After 30 days, the corals were removed from the aquarium. In a clean bench, the coral polyps were scraped off using a sterile scalpel. The coral polyp samples were placed in 50 mL test tubes containing 30 mL of sterile phosphate-buffered saline (PBS) solution and vigorously stirred to mix. Six corals were selected for each treatment to collect polyp samples (n = 6). DNA was extracted from the coral polyps using the FastDNA™ Spin Kit according to the manufacturer's instructions and eluted with 50 μL LDES. DNA was extracted from the coral polyp samples using the CTAB method. The DNA concentration and mass of the samples were measured using a Nanodrop spectrophotometer.

[0070] II. Analysis of Test Results

[0071] 1. High-throughput sequencing data analysis

[0072] High-throughput sequencing was performed on the V3-V4 regions of the 16S rRNA gene in the polyps of *Torchella flamingo*, as well as the ITS rRNA sequences, which typically include ITS1, 5.8S, and ITS2. After quality control and sequence filtering, a total of 656,521 16S rRNA sequences and 610,947 ITS rRNA sequences were recorded. After optimization of the original sequences based on 97% similarity, they were clustered into 5,682 bacterial OTUs and 2,704 fungal OTUs, respectively. Venn diagrams represent the number of common and unique microorganisms among different groups, visually demonstrating the overlap of characteristics between samples. Shannon and Chao1 indices represent the diversity and richness of the microbial community, respectively. Non-metric multidimensional scaling (NMDS) was used to analyze whether there were significant differences in the microbial community structure and composition among the treatment groups.

[0073] 2. Results of bacterial community analysis

[0074] (1) Analysis of the common and unique microbial effects of natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1 on the symbiotic microbial community of torch coral.

[0075] like Figure 1 As shown, after feeding the coral with the compound small molecule coral food of Example 1, the number of coral-specific OTUs was 893, which was lower than the 1577 in Comparative Example 1. The total number of microbial OTUs in the two treatment groups was 819.

[0076] (2) Analysis of the α-diversity of the symbiotic bacterial community of torch corals during natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1

[0077] Alpha diversity in the control group (CK) and the combined small molecule coral diet-fed group (FD) was analyzed based on 97% sequence similarity using OTU, and the diversity of symbiotic bacteria in each treatment group (Chao1 and Shannon indices) was assessed. The results showed that ( Figure 2 , Figure 3 Compared to the control group (CK), the Chao1 and Shannon indices of the corals in the feeding group decreased. This indicates that the α-diversity and species richness of the microorganisms in the coral symbiotic microorganisms were reduced in the FD group, and that the use of compound small molecule coral food can alter the bacterial diversity and species richness of the coral symbiotic microorganisms.

[0078] (3) Analysis of the β-diversity of the symbiotic bacterial community of torch corals during natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1

[0079] For β diversity, NMDS analysis showed relatively clear clustering patterns of bacterial communities in each treatment group. Figure 4 NMDS analysis showed that the 95% confidence ellipse of the control group (CK) was significantly larger than that of the feeding group (FD), but there was still a large overlap between the two, indicating that the bacterial communities under these treatments were similar. The enrichment levels at each point in the feeding group (FD) were higher than those in the control group (CK), indicating that the degree of difference within the FD group was less than that in the control group (CK). (Stress = 0.0734).

[0080] (4) Analysis of the effects of natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1 on the phylum-level community of the symbiotic bacterial community of torch coral.

[0081] Table 1. Horizontal community composition of coral symbiotic bacteria under different treatments.

[0082]

[0083] After feeding with compound small-molecule coral food (Table 1), compared with the control group, the dominant bacterial communities at the coral symbiotic bacterial level decreased by 2.67%, 3.90%, 0.83%, 0.86%, and 0.66%, respectively; while the proportions of Firmicutes, Verrucomicrobiota, Acidobacteriota, and Gemmatimonadota increased by 3.26%, 6.01%, 0.09%, and 0.25%, respectively. The FD group showed the highest increase in Verrucomicrobia, and some Verrucomicrobia phyla made significant contributions to the degradation of polysaccharides and xylan. The genome encodes various glycoside hydrolases, sulfatases, peptidases, carbohydrate lyases, and esterases, possessing mechanisms for hydrolyzing various polysaccharides. This demonstrates that feeding corals with a compound small-molecule coral diet affects the symbiotic microbial community of corals, resulting in significant changes in its community composition. Figure 5 ).

[0084] (5) Analysis of the impact of natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1 on the target-level community of the symbiotic bacterial community of torch coral.

[0085] Table 2. Horizontal community composition of coral symbiotic bacteria under different treatments.

[0086]

[0087] After feeding with compound small-molecule coral diet (Table 2), compared with the control group, the dominant bacterial communities at the order level of coral symbiotic bacteria showed the following changes: Burkholderiales, Bacteroidales, and Rhizobiales decreased by 2.95%, 4.20%, and 1.72%, respectively; while Pseudomonadales, Verrucomicrobiales, Enterobacterales, Lactobacillales, Oscillospirales, and Peptostreptococcales-Tissierellales increased by 1.93%, 6.11%, 3.11%, 0.19%, 0.25%, and 2.55%, respectively. The Verrucomicrobiales group showed the highest increase in the FD group, which is consistent with the changes in phylum-level community composition. This demonstrates that feeding corals with compound small-molecule coral food affects the symbiotic microbial community of corals, resulting in significant changes in its community composition. Figure 6 ).

[0088] (6) Prediction of BugBase phenotype of symbiotic bacterial community of torch coral by natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1

[0089] Bugbase is used to predict the phenotypes of prokaryotic microorganisms in human or environmental samples, mainly including the following aspects: Gram-negative, Gram-positive, oxygen tolerance, biofilm synthesis, pathogenicity potential, motile element content, and oxidative stress tolerance. Stress resistance phenotypes include... Figure 7 As shown, the abundance of stress-resistant microorganisms in the FD group after feeding with the compound small-molecule coral diet of Example 1 was higher than that in the control group CK. Alcaligenaceae, Halomonasaceae, and Oxalobacteraceae were detected in both treatment groups; however, two family-level microorganisms, namely Endozoicimonaceae and Enterobacteriaceae, were only detected in the FD group. Gram-negative phenotypes were observed as follows: Figure 8As shown, the abundance of Gram-negative phenotype microorganisms in the FD group after feeding with the compound small-molecule coral diet of Example 1 was lower than that in the control group CK. Peptostreptococcaceae, Mycoplasmataceae, Microbacteriaceae, Lactobacillaceae, and Clostridiaceae were detected in both groups. Each group also exhibited unique microorganisms. Specifically, Mycobacteriaceae, Erysipelotrichaceae, and Acidimicrobiales were only detected in the control group CK; Staphylococcus and Lactobacillales were only detected in the FD group.

[0090] The increased relative abundance of stress-resistant microorganisms in the FD group indicates that the coral symbiotic microbial community's ability to resist adverse external environments is enhanced, thereby maintaining the stability of the coral symbiosis. Gram-negative bacteria include many pathogenic microorganisms. Compared with the CK group, the abundance of Gram-negative bacteria in the FD group was reduced, indicating that the number of pathogenic microorganisms in the FD group was reduced, and the chance of the coral symbiosis becoming pathogenic was decreased.

[0091] 3. Results of fungal community analysis

[0092] (1) Analysis of the common and unique microbial effects of natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1 on the symbiotic bacterial community of torch coral.

[0093] like Figure 9 As shown, after feeding the corals with the compound small molecule coral diet of Example 1, the number of unique OTUs in the FD group was 206, which was an increase compared to 118 in Comparative Example 1. The total number of microbial OTUs in both treatment groups was 325.

[0094] (2) Analysis of the α-diversity of the symbiotic fungal community of torch coral during natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1

[0095] Alpha diversity of the control group (CK) and the combined small molecule coral diet-fed group (FD) was analyzed based on 97% sequence similarity using OTU, and the diversity of symbiotic fungi in each treatment was assessed using the Chao1 and Shannon indices. The results showed that ( Figure 10 , Figure 11Compared to the control group (CK), the Chao1 and Shannon indices of the corals in the feeding group were both increased. This indicates that the microbial α-diversity and species richness in the symbiotic microorganisms of corals were increased in the FD group, further demonstrating that the use of compound small molecule coral diets can alter the fungal diversity and species richness of coral symbiotic microorganisms.

[0096] (3) Analysis of the β-diversity of the symbiotic fungal community of torch coral during natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1

[0097] For β-diversity, NMDS analysis showed relatively clear clustering patterns of fungal communities in each treatment group. Figure 12 NMDS analysis showed that the 95% confidence ellipse of the control group (CK) was significantly larger than that of the feeding group (FD), and the two almost overlapped, indicating a significant difference between the fungal community under FD treatment and the CK group. The enrichment levels at each point in the feeding group (FD) were higher than those in the control group (CK), indicating that the degree of difference within the FD group was less than that in the control group (CK). (Stress = 0.0974).

[0098] (4) Analysis of the effects of natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1 on the phylum-level community of the symbiotic fungal community of torch coral.

[0099] Table 3. Horizontal community composition of coral symbiotic fungi under different treatments.

[0100]

[0101] After feeding with a compound small-molecule coral diet (Table 3), compared with the control group, the dominant fungal communities at the coral symbiotic fungal level decreased by 0.21%, 0.73%, 0.82%, and 1.09% for Chlorophyta, Ciliophora, Arthropoda, and Intramacronucleata, respectively; while the dominant fungal communities increased by 14.00%, 19.76%, 13.23%, and 0.15% for Ascomycota, Streptophyta, Cnidaria, and Basidiomycota, respectively. The FD group showed the highest increase in Streptophyta, followed by Ascomycota and Cnidaria. This demonstrates that feeding with a compound small-molecule coral diet affects the coral symbiotic microbial community, causing significant changes in its community composition. Figure 13 ).

[0102] (5) Analysis of the impact of natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1 on the target-level community of the symbiotic fungal community of torch coral.

[0103] Table 4. Horizontal community composition of coral symbiotic fungi under different treatments.

[0104]

[0105] After feeding with compound small-molecule coral food (Table 4), compared with the CK group, the dominant fungal communities at the symbiotic fungal level in the FD group showed a decrease of 40.32% and 0.80% in Suessiales and Ephemeroptera, respectively; while the communities of Saccharomycetales, Poales, Caryophyllales, and Protosiphonales increased by 14.07%, 10.88%, 8.11%, and 0.40%, respectively. The FD group showed the highest decrease in Suessiales, while the increases in Saccharomycetales and Poales were both greater than 10%. This demonstrates that feeding with compound small-molecule coral food affects the symbiotic microbial community of corals, resulting in significant changes in its community composition. Figure 14 ).

[0106] (6) Prediction of FUNGuid fungal phenotype in the symbiotic fungal community of torch coral by natural growth of the compound small molecule coral diet corresponding to Example 1 and the additive-free diet of Comparative Example 1

[0107] FUNGuild (Fungi Functional Guild) is a tool for analyzing fungi using ecological association taxonomy, classifying large sequence libraries into ecologically significant categories in a simple and consistent manner. Fungi are classified into three main groups based on their mode of nutrition: pathotrophs, symbiotrophs, and saprotrophs.

[0108] Table 6. Phenotypic prediction composition of FUNGuild fungi in coral symbiotic fungi under different treatments.

[0109]

[0110] After feeding with a compound small-molecule coral diet (Table 5), the composition of symbiotic fungi in the FD group changed. Compared with the CK group, the saprotrophic fungi increased by 6.11% in the FD group, while the pathotrophic and symbiotrophic fungi decreased by 5.41% and 0.70%, respectively. FUNGuild fungal phenotypic prediction is as follows: Figure 15 As shown.

[0111] The altered fungal phenotypic composition demonstrates that feeding corals with compound small-molecule coral food changes their nutritional patterns, thereby affecting the nutritional patterns of symbiotic fungi. The decrease in the content of pathotrophic fungi proves that compound small-molecule coral food can reduce the number of fungi that obtain nutrients by damaging host cells (including phagocytic fungi), thus maintaining the stability of the coral symbiosis and reducing the disease rate of the coral symbiosis.

[0112] The same verification experiments were conducted on the composite small molecule coral food of Examples 2-5, and the results were comparable to those of Example 1, proving that the composite small molecule coral food provided by the present invention can adjust the coral symbiotic microbial community.

[0113] Furthermore, during preliminary experiments, the inventors discovered that feeding corals with a single component, such as soybean meal peptide protein, did not promote coral growth. When the proportions of each component in the compound small-molecule coral food exceed the scope of protection of this application, it will have a negative impact on the aquaculture water quality, easily causing water quality deterioration, inhibiting coral growth, or even causing coral death.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite small molecule coral food, characterized in that, The raw materials of the composite small molecule coral food, by weight, include: 30-50 parts soybean meal small peptide protein, 20-35 parts cod small peptide protein, 10-15 parts Haematococcus pluvialis powder, 3-5 parts compound amino acids, 2-5 parts squid powder, 5-10 parts chitosan oligosaccharide, and 3-5 parts compound nucleotides.

2. The preparation method of the composite small molecule coral food as described in claim 1, characterized in that, include: Soybean meal small peptide protein, cod small peptide protein, Haematococcus pluvialis powder, compound amino acids, squid powder, chitosan oligosaccharide and compound nucleotides are mixed in proportion, then crushed and sieved, and then the sieved powder is heated and dried to obtain the compound small molecule coral food.

3. The method for preparing the composite small molecule coral food according to claim 2, characterized in that, The sieve mesh size is 160-200 mesh.

4. The preparation method of the composite small molecule coral food according to claim 3, characterized in that, The moisture content of the dried composite small molecule coral food is ≤10%.

5. The application of the composite small molecule coral food as described in claim 1 in adjusting the structure of coral symbiotic microbial communities.

6. The application according to claim 5, characterized in that, The corals mentioned include torch corals.

7. The application according to claim 6, characterized in that, The adjustment of coral symbiotic microbial community structure includes reducing bacterial α diversity and species richness, increasing fungal α diversity and species richness, increasing the abundance of stress-resistant microorganisms, and reducing the abundance of pathogenic microorganisms.

8. The application according to claim 7, characterized in that, The application includes adding the compound small molecule coral food to an aquarium for cultivation, wherein the addition ratio of the compound small molecule coral food in the aquarium is 0.005-0.02 g / L.

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