Yeast in aquaculture


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Yeast products are getting more and more popular in aquaculture. However many products (as a whole or as fractions) are on the aquaculture market at the moment and differentiating between one from another can be difficult. This small article aims at shading some lights on the subject and explains that all yeast products are not equal.

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Yeast in aquaculture

  1. 1. November | December 2012 Yeast in aquaculture International Aquafeed is published five times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2012 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058The International magazine for the aquaculture feed industry
  2. 2. FEATUREYeast in aquacultureby Philippe Tacon PhD, Lesaffre Feed Additives, FranceY east products are getting more shrimp and marine fish larval feeds or included Nutritional properties of yeast: and more popular in aquaculture. as a protein source in aquafeeds. Typical dry yeast composition is 93-97 However many products (as a The reasons for this extensive use is its percent dry matter and can contain from 40% whole or as fractions) are on the excellent nutritional contents, its easy supply to 60 percent crude protein nitrogen, 35-45aquaculture market at the moment and dif- in dried form or under liquid form when percent carbohydrates, and 5-9 percent lipids.ferentiating between one from another can bakery yeast plants or breweries are near A quite important fraction of the nitrogen isbe difficult. This small article aims at shading aquafeed plants, and nowadays a competitive under the form on nucleic acids (up to 12%)some lights on the subject and explains that price in regards to other protein sources such that can lead to produce significant level ofall yeast products are not equal. as fish or soybean meal. Further applications uric acid if consumed at high concentra- are being developed for yeast as functional tion, like meat. The Amino acid profile of Yeast is a unicellular organism belonging to feed additives as probiotic live yeast, yeast yeast is close to soybean meal and thereforethe kingdom of Fungi. More than a thousand fractions (yeast cell walls, yeast extracts) or as well adapted to animal nutrition; it is rich inspecies have been found in two major phyla: a source for more purified products such as Glutamic acid and Lysine (up to 8%). YeastBasidiomycota and Ascomycota in which beta-glucans and nucleotides. The production is naturally rich in B vitamins such as biotin,belong species able to duplicate by budding process of yeast can allow the possibility to thiamine and folic acid. It also produces niacinsuch as Saccharomyces cerevisiae. incorporate trace minerals and then produce but contrary to some belief does not produce Due to their unique properties to grow highly bioavailable organic trace minerals, also B12 Vitamin. Ergosterol which is a significantunder aerobic conditions and produce gas known as selenium and chromium yeast. fraction of yeast cell wall, also is also a precur-and ethanol under anaerobic conditions, some The pink yeast Phaffia rhodozyma, is natu- sor of Vitamin D2 by using UV treatments.yeast (mostly S. cerevisiae) have been used rally rich in astaxanthin and has been used forfor the manufacture of fermented foods such some time as natural source of the pigment Baker’s yeastas bread , beer and wine for a long time. in salmonids. Although now it tends to be Even if their name remains SaccharomycesYeasts are also used as single sell protein replaced by bacterial products which have a cerevisiae (cerevisiae for beer), most of thesource in animal nutrition and in aquaculture higher concentration and whose cell wall is strains of Baker’s yeast have been selectedunder various forms and species (Torulaspora, more easily degraded. We will only refer in for their high fermentative power, particularlyTorulopsis, Kluyveromyces, Saccharomyce et the following article on products coming from useful for bakers.Strains are specific to thecaetera). It can be found for example in S. cerevisiae origin. type of bread and the region where it is sold, in order to respond to different bread making conditions (French bread, white bread, flat bread, croissant, etc.) and resist to different process conditions (osmotic pressure from high sugared bread, freezing, acidity of sour dough,…). Baker’s yeast comes as a pure and pri- mary culture grown on sugar substrate such as molasses. The production is performed under very strict conditions in order to main- tain the genetic purity, consistency, specificity and efficacy of the strains. (Figure 1). It can be sold under different forms and packaging (instant dried yeast, active dry yeast, com- pressed, cream). The primary grown culture controlled process makes also a very consistent base for the production of yeast extracts, autolysed yeast, yeast cell walls and their derivate: nucleotides and beta-glucans. Yeast cell walls produced from Baker’s yeast usually Figure 1: Yeast manufacturing process (primary grown culture) have a high content of mannans. They are 14 | InternatIonal AquAFeed | november-December 2012
  3. 3. FEATURE FEATURE important for vaccinator safety but on growth parameters in tilapia a Table 1: Effect of live yeast Actisaf also the encounters as under stress conditions. fish. contract vaccina- safety and welfare of the(n=3, P<0.05, measures with different letters are significantly different) The fish are then delivered onto a stainless tion team, is poor steel table where the fish then(%) vaccinated anaesthesia of PER Treatment Survival are SGR FCR the in a very specific area, with only a 3 mm toler- fish and also poor ance. The team must achieve a 96 percent grading, prior to vac- CON 40% -10 fry 75.0ab 3.33a 3.11e 0.83ab accuracy target and considering most vaccina- cination of the fish. CON 40% -20 fry 64.8a 3.47a 3.26e tors handle between 15-20,000 fish each this Poor anaesthesia of 0.78ab is quite 40% - achievement! Act some 10 fry 87.5bc 5.80d 1.43abc 1.89cd the fish can lead to The 40% are then returned to a recovery high mortalities. If Act fish - 20 fry 92.6c 5.43c 1.01a 2.64d tankAct 27% - 10come round from the anaes- fish are under anaes- and should fry 91.7bc 5.46cd 1.62bc 2.26c thetic within about two to three minutes. thetised, the whole Act 27% - 20 fry 96.29c 5.24c 1.17ab 3.17e There is always some level of mortality after process becomes this high risk, stressful process but usually it is stressful and danger- just a few fish, around toxin for every 100,000 ous for dried. It can also recognised as good 100 binders. Fractions drum them (imag- Figure 2: Schema of a process to produce yeast fish vaccinated.baker’s mortalities immediately ine having a as a more coming from High yeast have a light beige been grown major extracts and yeast cell walls colour. controlled product and after vaccination are usually attributed to poor operation whilst anaesthesia rather than aquaculture application only partly sedated!). find The most popular the injection. specific strains and of The consequenceshatcheries where it is a On way to human care as a food supplement tively high and and its amino acid content is Baker’s yeast is in of poor vaccination its the other hand, major feed source forapparent and rotifer (see ifand holistic therapeutic, also known as natural similar to baker’s yeast. Numerous works usually only become artemia months after they are over vaccination and can last et al 1990). brewer’s yeast. for example Couteau up until harvest where anaesthetised, they have shown the efficacy of Brewer’s yeast to Brewer’s yeast for aquafeed applications replace partially or totally the proteins found the financially consequences become appar- risk not recover- Brewer’s Yeast ent. The main problems are: ing sold by trading companies as a commodity in fish and vegetable meal in fish and shrimp. is quickly enough, Incorrect needle depth resulting in either resultingon the protein content, or by local Shrimp feeds formulators typically incorporate Brewer’s yeast can be identified either based in piles of as the ferment used (needle too short) or fish in the in need to dispatch their slurry. The brewer’s yeast in their formula at the rate of intra-muscular injection in brewery industries breweries recovery internal primary damage, including granuloma tank causing the supply of these products can two to four percent. (Yeast organ production) or the by-product quality and suffoca- (needle too long) which results in the fish not tion inconsistent and depends greatly on the of these industries which is the form mainly be or even worse, Brewer’s yeast can be used to produce used in properly due to damage tocase, gut. growing source of supply. aquaculture. In the latter the yeast not recovering at all. yeast fractions, however due to the nature of biomassnot harvested from the the disease Fish is being immune to fermentation The nutritional content is similar as the brewer’s yeast and the specificity of the pro- The other risk because of incorrect dosage (or no It can be one here is to the Innovative and proven vats at the end of beer fermentation. vaccine) factorin baker’s yeast, but contains more trace duction processes, the quality is less consistent being under liquid form (18-20% of dry matter) vaccinators. If as selenium and chromium. than in baker’s yeast. Products coming from sold delivered. minerals such the as problems spray or 29/10/2012 13:57 Two ridgewaybio_quarterpage_print.pdf of the yeast products but preferentiallymaininactive yeastSalmovac1 mineral oils used in of brewer yeast is rela- brewery yeast tend to have a distinctive bitter The protein content in aquaculture Consistent products supported by the Lesaffre group experience and its unique know-how in biotechnology and nutrition; Selected strains and controlled production; VIV Russia 2013 Designed to solve nutritional and sanitary issues; May 21-23, 2013 | Moscow, Russia C Dedicated range of products: live yeast, yeast cell wall, yeast extract M and enriched yeast. YCMMYCYCMY K REGISTER NOW for FREE entrance at Special themes Opening the gates to the rformance Russian Feed to Meat trade. Wellbeing, the source of pe For more information: november-December 2012 | InternatIonal AquAFeed | 15 november-December 2012 | InternatIonal AquAFeed | 11
  4. 4. FEATURE enzymes (notably pro- transfer from lab conditions to farm using teolysis) or playing on commercial feeds. the osmotic pressure All the work published so far was made to rupture the cell wall with yeast either top dressed on feeds or (plasmolysis). Different incorporated in pressed (uncooked) feeds. grades of autolysed Nevertheless some direct effects to the gut yeast can be obtained maturation have been found in sea bass with a depending on the level species extracted from the rainbow trout gut of autolysis (from partial Debaryomyces hansenii (see the works from to total). The final prod- Tovar-Ramirez and also the reviews by Chi et uct is a mixture of cel- al 2006 and Gatesoupe 2007). Marine yeasts lular content and yeast and yeasts isolated from fish seem a very Figure 4: Cumulative mortality after immersion cell wall. Furthermore logical choice to use in species of aquaculture with L. anguiilarum (blue line is control, orange line is Pronady at 0.5g/kg. n=3, Pronady significantly the autolysis process interest. However, such material is often dif- decreases mortality at 120h. P<0.01) degrades protein and ficult to grow under industrial conditions and forms peptides (dipep- did not lead to the development of an actual tides to tetra peptides) product yet. The products on the market aresmell and taste and a darker colour than the and oligonucleic acids which are readily digest- therefore often from S. cerevisiae origin. It hasones coming from baker’s yeast. ible by the animal. Again here depending on to be noted that up to now, no yeast prod- the original yeast material used, autolysed and ucts have been registered in EU as a probioticEthanol Yeast inactive yeast quality can be very different. in aquaculture. Ethanol Yeast are harvested after hav- As an example of S. cerevisiae effects,ing performed alcoholic fermentation and Live Yeast as probiotics (Lara Flores et al 2003, 2010) Table 2 showsdistillation for the conventional production Live yeast helps regulate the gut microbio- some works done in tilapia fry fed for 3 weeksof Bioethanol from sugarcane, beet sugar ta. Its effects have been shown, first in human with feeds supplemented with Actisaf (alsoor grains syrup. In the first case, the yeast where it can reduce diarrhoea, especially knwn as Biosaf) at 1 kg/T in two diets (40%biomass is harvested and then dried with with children. Specific strains have then been and 27% proteins) and at 2 crowded condi-the recycled energy used to heat the vegetal developed and produced industrially such as tions (1 fry per L or 1 fry per 2L).material. The majority of ethanol yeast comes S. cerevisiae boulardii or S. cerevisiae Sc 47 All the yeast treatments also increased thefrom Brazil. (Actisaf) for the animal nutrition market. It is alkaline Phosphatase activity, and we can see a Production prices and selling prices are a common practice now to supplement feeds better improvement of feed conversion ratiovery low, however the quality, such as the to increase milk production in dairy cows (FCR) and survival under stressful conditionsprotein content is very inconsistent. The sup- or help pigletsply depends on the activity of the bioethanol survival.plants and can also be inconsistent. Another Live yeastconcern is the sanitary safety of these prod- are charac-ucts. Antibiotics are sometimes added to the terized byprocess in order to prevent bacteria compet- their livinging with the yeast for nutrients andavoiding cells count,yield decrease. It is therefore possible that expressed bysome antibiotic residues and possibly other colony formingtoxins might be left in the final dried product. unit (cfu per Autolysed yeast – Inactive Dried Yeast gram), typically Inactive and Autolysed yeast come from ten billionsprimary grown cultures or Brewer’s yeast. cfu/g. DosagesThey are major products within the food are made inindustry as flavour enhancers and in pet food the feeds as Figure 3: Number of pellets remaining in the feeding tray one hour after feeding (n=4, YE are significantly different thanas feed attractants. They are used in aquacul- dilutions to get control at P<0.05).ture feeds as a source of protein and nitrogen. an efficient cfuBrewer’s yeast, and its ethanol equivalent, is count per g ofmostly favoured as it is cheaper than baker’s feed, a 1000 fold dilution giving a 10e107 per (low protein percentage and crowded condi-yeast. They are also easier supplied as yeast g of feed for example. Viability of the yeast is tions). There is also a better protein efficiencysuppliers prefer to sell the more controlled mandatory for its effect and cfus should be ratio (PER) and digestive enzyme activityand tailored Baker’s yeast on food markets. checked before and after pelleting using plate when Actisaf is used. Inactive yeast is a yeast that has been counts. Live yeast can be used directly on farm,deactivated by high temperature drying (often Despite the increasing use of yeast as where it has been showed (empirically) tospray drying). The cells come as a whole a probiotic in terrestrial animals, there improve water quality in shrimp and fishand the cell wall is not ruptured making the are only a few numbers of works studying ponds. It is either used alone or mixed withaccess to intracellular material (amino acids, its effect in fish as a gut functions stabi- bacteria. Farms producing mash feed onsitevitamins…) difficult. A way to access these liser. The major reason is that live yeast also add yeast in order to degrade cellulolyticmaterials is to partially hydrolyse the yeast does not resist the severe conditions of material to ensure a better digestion.cell wall to let the cellular content be partially the manufacturing processes of aquafeedsreleased from the cell. This can be facilitated (high temperatures, steam, long condi- Yeast Culture or fermented activating the internal autolytic enzymes tioning times, see Aguirre-Guzzman et al Yeast culture is a particular product inof the live yeast (autolysis), adding external 2002). The studies are then difficult to which yeast is allowed to ferment. Yeast bio- 16 | InternatIonal AquAFeed | november-December 2012
  5. 5. FEATURE Figure 5: Yeast rich in organic selenium manufacturing processmass, substrate and fermented extracellular in functional feeds, and hatcheries, as a aquafeed in shrimp. In a trial performed inmetabolites are then dried. source of nucleotides complementing the Thailand with white shrimp L. vannamei. de novo synthesis of cells in multiplication Feed containing YE at 2 kg/T of feed wasYeast Extracts. and helping boost immunity and anti-stress presented in feeding trays at the corner of Yeast extracts (YE) come from the mechanisms. hapas and the remaining feed was countedfurther hydrolysis and purification of Autolysed yeast and inactive yeast are after one hour. We can see a faster feed-autolysed yeast. Insoluble yeast cell walls commonly mistakenly sold on the label ing when YE are included. (Tacon andare separated from the cellular content yeast extract in aquaculture. A good way Suyawanish 2011).by centrifugation. YE are very soluble, to differentiate them is to look at therich in peptides (up to 65%-70% of the carbohydrate levels. Autolysed yeast has Yeast Cell wallsproduct), free amino-acids like glutamic around 20-22% (mostly from the remaining Yeast Cell Walls (YCW) representacid and vitamins. They also contain a high YCW) whereas YE contain only three to the shell of the yeast cell and are roughlylevel of nucleic acid which can be further six percent of carbohydrates. 40-50 percent of the mass of the cell.purified to increase the level of tasty 5’ The small peptides and free amino acids YCW are composed mainly of fibrousnucleotides. They are used in aquaculture in YE can also prove a potent attractant for polysaccharides glucans with beta 1,3 and MADE IN HOLLAND AL30O High capacity extruders and expanders.  AD System Almex b.v., Verlengde Ooyerhoekseweg 29, 7207 BJ Zutphen, The Netherlands, tel. +31 (0)575 572666, e-mail, november-December 2012 | InternatIonal AquAFeed | 17
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  7. 7. FEATURE FEATURE a beta 1,6 links, (50% and 8% respectively ), tration (2 kg/T) only for a short period, or as both alpha and beta forms)or mannans. s are mannans under the form of Mannoproteins a low concentration continuously (0.5 g/Kg). Not all the YCW are equal. Efficiency should (40%) and chitin (2%) (see Lippke and An example of sea-bass juveniles fed with be checked as a prerequisite to use, or PER Ovalle 1998). Further purification can lead Pronady (a YCW of the Lesaffre group) at change, YCW. to the production of either purified beta- 0.5 g/kg of feed for 8 weeks can be seen At LFA we have conducted a survey .83ab glucans (50% and up) and mannoprotein in Figure 4, showing a significant protection of four YCW (2 bakery and 2 brewery (often used in wine making for clarifica- against L. Anguillarum without any growth yeasts) produced in 4 of our own factories .78ab tion). The presence of these compounds difference with the control. However a mini- in the same L. Anguillarum challenge in sea .89cd often leads to the mislabelling of YCW as mal amount of YCW seems needed to be bass supplemented at 0.5 g/kg of feed for2.64d MOS or Beta-glucans. ingested before challenge in order to provide 8 weeks. Only 2 responded significantly (1 2.26c These two carbohydrate types are very an efficient immunostimulation and so there bakery, 1 brewery), the remaining 2 had even 3.17e interesting for the aquaculture market, beta- might be a gap period when the product is negative results at 4 weeks (lower survival glucans are direct stimulators of the immune not efficient. (data from Dr. Morgane Henry, than control). This result shows first that not systems in shrimp and fish, upon the stimula- Hellenic Center for marine Research , 2011) all is understood in the way these products can also tion of specific Schemacellsa(granulocytes or Figure 2: blood of process to produce yeast YCW products, depending on the quality work and that one particular YCW cannot s a more Mannans are involved in the of the autolysed yeast separation, contain macrophages). and yeast cell walls extracts be replaced by another. duct and binding to pathogenic bacteria (especially also significant percentages of proteins and and find those with pili having mannose receptors) lipids. It should be noted that the lower the Selenium Yeastman care as a food supplement tively high intestine. its amino acid contentthe higher of level of carbo- and eliminate them from the and and It level of proteins, is Yeast can be induced to be a source of rapeutic, also known as naturalthatsimilar to baker’s yeast. hydrates, and worksthe better immunostimu- is also suspected the mannanes act as Numerous then organic selenium, mainly under the form of prebiotics promoting the growth of the efficacy of Brewer’s yeast YCW is. Various quality of have shown beneficial lation from the to seleniomethionine, which is then stored ineast for aquafeed applications replace partially or totally YCW are on found bacteria. the proteins the animal production market proteins. During the growth of baker’s yeast, ng companies as a commodity shown and be effective and fish and shrimp. can be found between YCW have been in fish to vegetable meal in major differences selenium is added to the medium and is protein content, or bythe resistance to feeds formulators typically incorporate on the strain, the sub- to improve local Shrimp bacterial chal- products depending replacing sulphur in methionine. The excesseed to dispatch their slurry. The aquaculture yeast in their formula at theto produce the yeast, and event lenges in numerous brewer’s species. Beta strate used rate of of selenium is then eliminated by careful glucans have to be two to four percent. supply of these products can use carefully in aquacul- the drying process. washing steps (see Figure 5) to ensure that t and depends greatly on experiments report yeast can be used to produce ture as some the Brewer’s negative Mannans represent as most 25-27 per- the selenium left is 97-99 percent organic. ly. effects in fish when yeast fractions, however due to the naturegood quality YCW from pri- used for prolonged cent of YCW in of Selenium yeast should be then checked foronal content is similar high the brewer’s yeast and the specificity of the pro- but can be found as low periods at as concentrations.. This can be mary grown yeasts the highest percentage of selenomethio- yeast, but contains morecareful choosing processes, the quality 9 less consistent avoided by trace duction the source of as is percent in crude preparation coming nine and the consistency between batches. as selenium andand using them than in at high concen- Productsindustry by-products. Glucans or poly- YCW chromium. either baker’s yeast. from coming from Seleniomethionine is the main carbon-asso-ontent of brewer yeast is rela- brewery yeast tend to have a distinctive bitterfrom 18 To 40 percent. glucose can range ciated form of selenium in the animal’s body YCW Protein and then allow making organic selenium level remains which are readily available when oxidative ming the most con- stress reactions occur. Upco r 2013 venient indica- The main application would be in aquacul- fo tor of quality, ture as fish meal is a main supply of selenium E vents World Aquaculture the best prod- and the development of diets with less fish ucts being those meal will require compensation of selenium The international triennial conference & exposition of having lower in aquafeed formulae. Such an application World Aquaculture Society nitrogen con- could be useful in preventing the oxidation3 tent. The vari- of poly unsaturated fatty acids (PUFA) in ability between fish flesh. Chromium yeast is seldom used in February 21 - 25, 2013 batches can also aquaculture diets. Nashville, Tennessee For all info contact us onsia be very high. USA Texture should Conclusion be checked first. Yeast products are getting more fre- Aquaculture Europe Good YCW quently used in aquaculture. Some appli- often have a cations are promising as the use as an August 9 - 12, 2013 smooth, fine alternative source of proteins or as a sanitary Trondheim, Norway texture, low and welfare enhancer. However many prod- Organised by European Aquaculture Society granulometry ucts ranging from crude ethanol yeast by- For all info contact us on and a light beige products to more purified beta-glucans are colour. There is available on the market. Therefore potentialW Making Sense of Science also the tenden- users must accurately select them in func- at cy to believe tion of their targeted application. It is also Asia Pacific Aquaculture that all YCW as important to select a reliable source of December 10-13th, are the same the products to ensure a consistency of the and that dif- supply. 2013 ferentiation of Ho Chi Minh City, Vietnam products must For all info contact us on be done to the More InforMatIon: highest level of Website: glucans (some- times measured 18 | InternatIonal AquAFeed | november-December 2012 012 | InternatIonal AquAFeed | 15
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  9. 9. This digital re-print is part of the November | December 2012 edition of International LINKSAquafeed magazine. Content from the magazine is available to view free-of-charge, both as a fullonline magazine on our website, and as an archive of individual features onthe docstoc website.Please click here to view our other publications on VO L U M E 1 5 I S S U E 6 2 0 1 2 • See the full issue An overview of the UK fish vaccination industry • Visit the International Aquafeed website Why check selenomethionine levels in selenium yeast? Extrusion technology for the production of micro-aquatic feeds • Contact the International Aquafeed Team and shrimp feeds EXPERT TOPIC – Salmon • Subscribe to International Aquafeed THE INTERNATIONAL MAGAZINE FOR THE AQUACULTURE FEED INDUSTRYIAF12.06.indd 1 07/11/2012 17:39To purchase a paper copy of the magazine, or to subscribe to the paperedition please contact our Circulation and Subscriptions Manager on the linkabove. INFORMATION FOR ADVERTISERS - CLICK HERE