Yeast as Potential source of Sustainable fish feed by B.pptx

Introduction about Yeast taxonomic position, importance and potential applications of yeast as sustainable feed in addition as probiotics. Its various applications

1. Yeast as Potential S ource of Probiotic Effects on Aquaculture, as Stimulation of the I mmune, Antioxidant Systems , Gut Maturation and Fish Growth By: Bhukya Bhaskar Fisheries Mechanism of yeast-derived β-glucans toward immunostimulation of fishes (Ref: Mohammed Mahdy et al , 2022) Ref: Grandview research

2. Introduction Yeasts are unicellular eukaryotic microorganisms that are taxonomically placed within the phyla Ascomycota and Basidiomycota within the Kingdom Fungi . Ascomycete yeasts comprise approximately 1,000 phylogenetically diverse species that have recently been assigned to 14 different lineages on the basis of multigene sequence analysis. The other species of yeasts are classified as the basidiomycetes . Some of the general characteristics and ecological properties of each phylum include the following: 1) the cell wall polysaccharide composition is dominated by chitin in the basidiomycetes and by β-glucans in the ascomycetes; 2) Guanine + cytosine (G + C) composition of the nuclear DNA tends to be higher than 50% in basidiomycetes and lower than 50% in ascomycetes ; 3 ) Ascomycetes yeasts are generally more fermentative, more copiotrophic (but at the same time nutritionally specialized), more fragrant , and mostly hyaline, while basidiomycete yeasts more often form mucoid colonies display intense carotenoid pigments and tend to use a broader range of carbon compounds more efficiently at lower concentrations

3. Cont … 4) Ascomycete yeasts are often found in specialized niches involving interactions with plants and insects or other invertebrate animals that they rely upon for dispersal, while basidiomycete yeasts seem to be adapted to the colonization of nutrient-poor solid surfaces and may not rely to the same extent on animal vectors for their dispersal In contrast to bacteria, yeast cells utilize a wide spectrum of simple and more complex organic compounds. This phenomenon results from the extensive metabolic potential of yeast, which is reflected by the production of diverse enzymes. Polyamines secreted by yeasts are also involved in the maturation of the digestive tract of fish larvae. Furthermore , some yeast species and their components, such as β-glucans and mannoproteins , can stimulate the immune and antioxidant systems of the host . Yeast has also been used as probiotics to provide better immunity against pathogens as well as to improve water quality of aquaculture resulting in better production of fishes . Yeast as major protein‐rich ingredient in aquafeeds In addition, yeast supplements and yeast-containing feed ingredients are used as a sustainable feed resource in aquaculture. The world yeast extracts for animal feed market size was valued at USD 298.3 million in 2021 and is anticipated to expand at a compound annual growth rate (CAGR) of 7.1% from 2022 to 2030. The demand for the product is due to the shift in the trends towards naturally-derived materials in animal feed. 

4. Yeast as part of the gut microbiota of fish Yeast have been isolated from the gills, skin, mouths, feces and guts of different fish species. The occurrence of yeast in the fish gut is variable and can fluctuate from non- detectable levels to 107 CFU/g of intestinal content. Both ascomycete and basidiomycete yeasts have been isolated from fish intestines: among ascomycetes, Saccharomyceta‐ceae (which include Candida, Pichia, Saccharomyces, and Debaryomyces ) is likely the most important family, while basidiomycetes, include the genera Rhodotorula , Cryptococcus, Sporo ‐ bolomyces , and Trichosporon . The yeasts Metschnikowia zobelii , Kloeckera apiculata , and Debaryomyces sp . dominate in some marine fish ( Tachurus symmetricus and Atherinopis affinis littoralis ).

5. Yeast as part of the gut microbiota of fish reported from different parts of the world

6. Effect of different diets containing some levels of yeast on fish growth performance (Ref: Corina Dumitrache et al, 2022) Saccharomyces cerevisiae

7. C ommonly used yeast species in aquaculture nutrition for higher growth and immunity of aquatic animal as well as for improvement of water quality Some of the yeast species used in aquaculture as probiotics for better growth performance, higher resistance to disease, and improved immune system of aquatic animals. (Ref: Mohammed Mahdy et al , 2022)

8. Oleaginous yeast as a component in fish feed (Ref: Johanna Blomqvist et al, 2018) Replacement of vegetable oil (VO) in aquaculture feed for Arctic char ( Salvelinus alpinus ) with oil produced by the oleaginous yeast  Lipomyces starkeyi  grown in lignocellulose (wheat straw) hydrolysate. VO is extensively used to partially replace fish oil in aquaculture feed, which can be seen as non-sustainable. VO itself is becoming a limited resource. Plant oils are used in many different applications, including food, feed and biodiesel. Its replacement in non-food applications is desirable. For this purpose, yeast cells containing 43% lipids per g dry weight were mechanically disrupted and incorporated into the fish feed. There were no significant differences in this pilot study, regarding weight and length gain, feed conversion ratio, specific growth rate, condition factor and hepatosomatic index between the control and the yeast oil fed group. Fatty and amino acid composition of diet from both groups was comparable . Their study reported that fish demonstrate that it is possible to replace VO by yeast oil produced from lignocellulose, which may broaden the range of raw materials for food production and add value to residual products of agriculture and forestry

9. Use of yeast as probiotics in aquaculture: stimulation of the immune and antioxidant systems, gut maturation and fish growth (Ref: In addition to S. cerevisiae, the halotolerant yeast D. hansenii has been considered an excellent probiotic candidate in fish aquaculture. Number of experiences reporting the use of D. hansenii is increasing, this allows us to know the capacity of this yeast to enhance growth, survival, and gut maturation and to improve of the immune and antioxidant systems in fish larvae and juveniles. Yeast cells can be a hundred times larger than bacterial cells, which may explain the fact that the introduction of a low yeast population (104 CFU/g) through feed can induce beneficial effects in the host. Yeast have immunostimulatory properties because they possess components such as β-glucan, mannoproteins , chitin (as a minor component) and nucleic acids. D. hansenii administration to the gilthead seabream ( Sparus aurata L .) significantly enhances leukocyte peroxidase and respiratory burst activity by week 4 of feeding with yeast . Yeast feeding causes an up-regulation in the expression of the immune-associated genes Hep, IgM, TCR-ß , NCCRP-1, MHC- IIa , CSF-1R, C3, TNF-α and IL-1ß in the head-kidney: C3 expression was only stimulated in the liver, whereas the expression of TCR-ß, TNF-α and C3 was stimulated in the intestine of S. aurata

10. Recent studies have shown the beneficial effect of dietary administered Saccharomyces cerevisiae in fish. Yeast supplemented diets stimulate growth, feed efficiency, blood biochemistry, survival rate, and non- specific immune responses in Uronema marinum -infected olive flounder ( Paralichthys olivaceus ). A diet supplemented with S. cerevisiae treated with beta- mercaptoethanol was better than whole cell yeast and n-3 highly unsaturated fatty acids (HUFA )-enriched yeast as an immune system and growth stimulator in juvenile rainbow trout challenged with Yersinia ruckeri The dietary administration of the probiotic S.cerevisiae P13 at a minimum level of 105 CFU/kg enhanced the growth, innate immune responses and disease resistance of grouper ( Epinephelus coioides ). Cellular yeast components also stimulate the immune system: an improvement in gut mucus lysozyme activity was observed in European sea bass ( Dicentrarchus labrax ) fed mannan oligosaccharides (MOS ) derived from the outer cell wall of a select strain of S. cerevisiae (Bio- Mos , Alltech Inc , USA)

11. Channel catfish ( Ictalurus punctatus ) juveniles fed diets supplemented with whole-cell S. cerevisiae ( Levucell SB20®) or yeast subcomponents such as commercial preparations of β- glucan ( MacroGard ® and Betagard A ®) had a significantly higher survival rate after Edwardsiella ictaluri challenge than did catfish fed with a controlled diet A diet supplemented with D. hansenii stimulates the immune system of juvenile leopard grouper, Mycteroperca rosacea , by increasing IgM and superoxide dismutase (SOD) activity and enhances the resistance of the fish to infection by the dinoflagellate, Amyloodinium ocellatum Studies have demonstrated the immune system improvement of M.rosacea when the fish were fed for 4 weeks with a compound diet enriched with 1.1% D.hansenii . After the 4 weeks, the fish were challenged with the pathogenic bacteria Aeromonas hydrophila strain Ah-315, resulting in an increase in IgM levels as well as catalase (CAT) and SOD activities in those fish fed yeast diets. Improvements were also observed at the molecular level , where CAT and HSP70 expression levels were enhanced in M. rosacea fed with D.hansenii , and challenged with A. hydrophila

12. Soybean meal, Probiotics role of Yeast & probiotic bacteria Soybean meal (SBM) has already become an important protein source in fish feed. However , the inclusion of some vegetable proteins, such as SBM, in the diets of fish at levels of >20% may induce intestinal disorders including patho -morphological changes in the distal intestinal epithelium accompanied by diarrhea , sometimes caused by the anti-nutritional factors that are present in SBM. The addition of probiotics (acid lactic bacteria) to starter diets appeared to improve SBM utilization in first feeding rainbow trout In larval gnotobiotic zebrafish studies, was shown that the microbiota also influences enterocyte morphology and epithelial renewal, host-transcriptional responses to the micro‐biota regarding epithelial proliferation, nutrient and xenobiotic metabolism, and immune responses. yeast have been used either alive to feed live food organisms or after processing as a feed ingredient after demonstrating an artificial colonization of the intestinal host. Even when accounting for less than 1% of the total microbial isolates in the host, yeast can represent a major physiological contribution beyond what has been observed for probiotic bacteria ; in fact, cell volumes from yeast may be larger than those of bacteria by a hundredfold

13. P olysaccharides used as prebiotics can stimulate the growth of beneficial microbiota in fish Ref: Paola Navarrete and Dariel Tovar-Ramírez, 2014

14. Biological effect of different β-glucans in fish

15. Conclusion & Prospects Potential of yeast, especially those of marine origin, has not yet been fully exploited. Yeasts can be part of the gut microbiota of wild and cultivated fish. It is reported by many studies on molecular aspects of yeasts, the exploration of the complete yeast community through the analysis of yeast DNA or RNA is lacking. The application of such methodologies will provide us with an overview of the non-cultivated yeasts, which could play a major role in the fish host. Different enzymes can be synthesized by yeast that have biotechnological potential , but the direct contribution of this potential to fish nutrition must be explored . In contrast , several publications confirm the beneficial probiotic effects of yeast in aquaculture, but the majority of these studies are focused on two species: S. cerevisiae and D. hansenii . The identification of new yeast species/strains from other cultured fish species is required to explore new beneficial properties to improve fish health and nutrition for a more sustainable aquaculture

16. References https://www.mdpi.com/2306-5710/2/4/30 https://landreclamationjournal.usamv.ro/pdf/2022/Art58.pdf https://www.nature.com/articles/s41598-018-34232-x https://www.researchgate.net/publication/260600349_Use_of_Yeasts_as_Probiotics_in_Fish_Aquaculture Paola Navarrete and Dariel Tovar-Ramírez, 2014. Use of Yeasts as Probiotics in Fish Aquaculture, In book: Sustainable Aquaculture Techniques, Chapter : Use of Yeasts as Probiotics in Fish Aquaculture; Publisher : INTECH; Editors : Martha Patricia Hernandez- Vergara and Carlos Ivan Perez-Rostro. Mohammed A. Mahdy1 , Mamdoh T. Jamal1 , Mamdouh Al-Harb1 , Bandar A. Al-Mur2 , Md Fazlul Haque3 * 2022. Use of yeasts in aquaculture nutrition and immunostimulation : A review. Journal of Applied Biology & Biotechnology Vol. 10(5), pp. 59-65, Sep-Oct, 2022 (DOI: 10.7324/JABB.2022.100507). https://www.grandviewresearch.com/industry-analysis/yeast-extracts-animal-feed-market-report Application of environmental-safe fermentation with  Saccharomyces cerevisiae  for increasing the cinnamon biological activities. (Ref: M . Darwesh et al, 2023) Yeast Extracts For Animal Feed Market Size, Share & Trends Analysis Report By Application (Poultry, Swine, Cattle, Aquaculture), By Region (APAC, North America), And Segment Forecasts, 2022 - 2030 Ref: Grandview research