Yeast Single Cell Protein Research Articles

Designing sustainable circular bioeconomy solutions for the pulse industry: The case of crude pea starch as a substrate for single cell protein production

Valorization of crude pea starch has become a key focus in the pea industry's sustainability pursuit. This study aimed to explore the circularity potential of crude pea starch as a nutrient-dense substrate for the solid-state cultivation of yeast (Saccharomyces cerevisiae) Single Cell Protein (SCP). Following the ISO 2006:14040/44 standard, a life cycle assessment (LCA) was performed to ascertain the environmental performance and operational dynamics of baseline and scenario pea starch-based yeast SCP process designs and identify optimal design considerations. Results demonstrated a higher relative contribution to the toxicity categories, with a relatively less contribution to global warming and land use. The distribution and media enrichment processes were identified as the hotspots, contributing about 32–55 % and 40–56 % to global warming and land use, respectively. Generally, train and air freight were more sustainable than lorry freight, respective of mileage and mass. Regarding system alteration, eliminating the media enrichment process could offset about 26 % of land footprint, with a similar trend for most impact categories. Process benchmarking showed up to a 3-fold reduction in global warming impacts relative to soybean meal, and about 71 % offset relative to fishmeal. Consequential LCA showed a general sustainability preference for substituting the aquacultural feeds with pea starch-based SCP, with a stronger emphasis on fishmeal substitution. Overall, these findings highlight the potential of the proposed SCP design as a sustainable upcycling solution with substitutionary potentials for conventional food and feeds, recommending further exploration in value and wealth creation.

Inverse metabolic engineering for improving protein content in Saccharomyces cerevisiae.

Production of Saccharomyces cerevisiae-based single cell protein (SCP) has recently received great attention due to the steady increase in the world's population and environmental issues. In this study, an inverse metabolic engineering approach was applied to improve the production of yeast SCP. Specifically, an S. cerevisiae mutant library, generated using UV-random mutagenesis, was screened for three rounds to isolate mutants with improved protein content and/or concentration. The #1021 mutant strain exhibited a respective 31% and 23% higher amino acid content and concentration than the parental S. cerevisiae D452-2 strain. Notably, the content, concentration, and composition of amino acids produced by the PAN2* strain, with a single nucleotide polymorphism in PAN2 coding for a catalytic subunit of the poly(A)-nuclease (PAN) deadenylation complex, were virtually identical to those produced by the #1021 mutant strain. In a glucose-limited fed-batch fermentation, the PAN2* strain produced 19.5g/L amino acids in 89h, which was 16% higher than that produced by the parental D452-2 strain. This study highlights the benefits of inverse metabolic engineering for enhancing the production titer and yield of target molecules without prior knowledge of rate-limiting steps involved in their biosynthetic pathways. This article is protected by copyright. All rights reserved.

Recovery and upcycling of residual lactic acid and ammonium from biowaste into yeast single cell protein

The yeast Saccharomyces cerevisiae is a potential candidate for converting waste resources into food-grade single cell protein (SCP). Food waste fermentation broth rich in lactic acid was tested as an alternative substrate source for S. cerevisiae in this study. An electrodialysis (ED) system was developed to recover lactate, acetate and ammonium ions (La-, Ac- and NH4+) from the broth. First, we evaluated the system resilience under various volatile fatty acids (VFAs) and pH levels. Initial acetate and lactate concentrations did not affect La- and Ac- recovery efficiencies but affected their ion fluxes and competitive ion transport. The migration of La- was delayed by increasing the initial acetate concentration, while Ac- migration was not affected by lactate concentrations. Increasing the broth pH reduced competitive H+ ions and thus improved the NH4+ recovery efficiency. Further, broth recirculation and pH control were examined to identify potential challenges associated with continuous flow in real-life applications. Recirculation caused a greater loss of recovered Ac- and NH4+ over the extended period. The pH control decreased VFAs recovery efficiencies because VFAs could not fully dissociate in the dilute, and more VFAs were lost in the concentrate. Finally, the recovery from lactate-rich fermentation broth was used as yeast substrate and contributed to a robust SCP yield of 0.62 g/g-C. Manufacturing one kilogram of SCP costs €6-10 in electricity and €3-6 in raw material. This study provides a better understanding of competitive ion transport during ED and uncovers potential biowaste resources for sustainable SCP production.

Recycling of acetate and ammonium from digestate for single cell protein production by a hybrid electrochemical-membrane fermentation process

Digestate is a potential substrate for yeast to produce single cell protein (SCP), but its complex matrix constrains applications. This study developed a hybrid electrochemical-membrane fermentation process to recover nutrients from synthetic digestate and produce yeast SCP. Electrodialysis (ED) was first employed to recover acetate and ammonium. More nutrients were recovered at a higher voltage but with lower current efficiency. At 2 V, 42.2% and 60.1% of acetate and ammonium were reclaimed, and further concentrated by 14- and 10-fold via a forward osmosis (FO) process. Due to the complexity of real digestate, the recovery efficiency of ED in practical applications should be further investigated. Saccharomyces cerevisiae fed on raw and concentrated recovery achieved similar SCP productions of 0.76–0.86 g/L, with amino acid concentrations above the FAO recommendation by 1.5–4.2-fold. The total production cost was estimated to be €20.4/kg-SCP by single ED, while the hybrid ED-FO process cost 40 times more.

Bioconversion of Saw Dust Powder Acid Hydrolysis to Single Cell Protein by the Yeast Candida tropicalis

This study was aimed to grow the local isolates yeast Candida tropicalis on locally prepared sawdust powder hydrolysate as a basal medium and carbon source with respect to single cell protein (SCP) production. The saw dust powder was treated with 10% H2SO4 for one hour at 100 0C. After cooling the supernatant containing the isolated sugar separated from debris by filtration and used as a carbon source and basal medium for yeast growth and SCP production. A high amount of SCP was achieved after five days of incubation, the percentage of the produced SCP 39.05% of the biomass dry weight, which is equivalent to 3.07g/l. SCP formation biosynthesis was affected by the level of nitrogen present in the medium; a high amount of protein being achieved in fermentation medium containing 0.3% urea in which the percentage of the yielded SCP was increased to 42.54%, (3.71g/l) of the biomass dry weight. The effect of varying nitrogen sources on SCP accumulation was also assayed. Medium containing ammonium phosphate greatly stimulated protein production in which the produced SCP was increased to reach 5.90 g/l. The produced amount equivalent to (48.22%) of the biomass dry weight. Conversely, a medium containing sodium nitrate had a suppressive effect on SCP production. This evidence clearly suggests that the metabolic versatility of Candida tropicalis may be employed in the conversion of low-grade material into high SCP product.

Alkaline hydrolysis of olive fruits wastes for the production of single cell protein by Candida lipolytica

This study aims to investigate the probable production of single-cell protein (SCP) through an identified yeast Candida lipolytica 10 DSM 70561, SM-0301 through the hydro-alkaline decomposition of the olive residuals by the recycling of the olive fruit residues and its use as a carbonic source for yeast growth and to provide the ideal circumstance to gain highest quantity of Carbohydrate of the hydro-alkali product. Alternation of the physical and chemical factors of the nutritional media in order to obtain the highest rate of production. The ideal state of this hydro-decomposition was as follows: 0.8 M of sodium hydroxide, temperature at 100 °C and duration time of 60 min. This context provided the highest sugar production, i.e. up to 12.5%. The ideal growth of the yeast and production of SCP was after 4 days of incubation with a rotation speed of 150 RPM at 30 °C and initial pH value of 5.5. Moreover, the medium containing 0.4% peptone as a source was superiors than other used peptone concentration with respect to yeast growth (17.55 g/l) and SCP production (11.24 g/l).

Conversion of Potato Industry Waste into Fodder Yeast Biomass

In this study, we evaluate potato pulp waste as a potential raw material for obtaining yeast biomass. A portion of the carbohydrates in the potato pulp waste can thereby be converted into more valuable protein. The potato pulp waste was analyzed in terms of protein and ash content, dry mass, simple sugars, and starch content. Two kinds of hydrolysis were performed (thermo-acidic and enzymatic) to produce media for cultivating Candida guilliermondii and Pichia stipitis. The hydrolysates and post-cultivation leachates were analyzed by High Performance Liquid Chromatography (HPLC). The highest biomass yield after 48 h (39.3%) was noted for Candida guilliermondii yeast grown on enzymatic hydrolysate-based medium. Our results prove that potato waste pulp is a promising raw material for the production of yeast single-cell protein (SCP).

Candida tropicalis able to produce yeast single cell protein using sugarcane bagasse hemicellulosic hydrolysate as carbon source

The world demand for foods will be the most important bottle-neck for human being maintenance. In this context, the research for alternative proteins sources aiming human and animal feeding is a necessary approach. A wild-type strain of Candida tropicalis (KP276650) was identified as potential yeast single cell protein (YSCP) producer using sugarcane bagasse hemicellulosic hydrolysate (SBHH) as substrate. Were evaluated the cell growth and sugar consumption along fermentation assay. Biomass yield (YB, gg−1), protein percentage (%), protein yield (YP, gg−1) and yeast biomass productivity (YBP, gL−1h−1) were calculated. Fermentation assay reach a total of 96h, being the total reducing sugar present in the media (59.94gL−1) fully consumed. Final biomass produced was 16.97gL−1, and the YBP was 0.1767gL−1h−1. Percentage of protein in yeast biomass produced was 60.05%, biomass yield (YB) and protein yield (YP) were, respectively, 0.28 and 0.17gg−1. The YB and YP obtained are close to the observed for some industrial strains of yeasts. The percentage of protein is greater than the expected for most of yeasts and fungi. These results indicate that the using of C. tropicalis (KP276650) for YSCP production may to aggregate high value for sugarcane bagasse.

English

An investigation was carried out to compare the effect of feeding yeast single cell protein (SCP) on the growth and feed utilization parameters of Clarias gariepinus and Oreochromis niloticus cultured separately. The parameters investigated include the percentage weight gain (PWG); feed conversion ratio (FCR); specific growth rate (SGR); and condition factor (CF). The findings indicate that for C. gariepinus fingerlings optimum growth and nutrient utilization was obtained with 30% SCP substitution of fishmeal while for O. niloticus fingerlings 50% substitution level gave optimum growth and feed utilization. Fishmeal could therefore be replaced with yeast SCP at these levels to cut down on cost of aquafeeds for sustainable aquaculture development of these species.   Key words: Yeast single cell protein (SCP), growth, nutrient utilization, catfish, tilapia.

Replacement of Fishmeal by Single Cell Protein Derived from Yeast Grown on Date (Phoenix dactylifera) Industry Waste in the Diet of Nile Tilapia (Oreochromis niloticus) Fingerlings

Isonitrogenous and isocaloric diets (32% protein, 4.3 Kcal/g) were formulated to replace fishmeal by single cell protein (SCP) from two yeasts, Saccharomyces cerevisiae and Candida utilis, grown on date (Phoenix dactylifera) processing waste in diets for two size groups (avg 15.39 g and 25.14 g) of juvenile Nile tilapia (Oreochromis niloticus). A control diet (T1) with fishmeal and six experimental diets (S1, S2, and S3 with S. cerevisiae, and C1, C2, and C3 with C. utilis) each containing 11.6%, 23.2%, and 34.2% yeast as SCP were prepared to replace 25%, 50%, and 75% of fishmeal, respectively. Tilapia fed on the control and experimental diets (S1, S2, C1, C2) with 25% and 50% replacement of fishmeal showed better growth and feed utilization. Fish fed on diets S3 and C3 (75% fishmeal replacement) had significantly (p < 0.05) poorer growth suggesting that yeast SCP can replace up to 50% of fishmeal in juvenile tilapia diets.

Cultivation of Candida utilis on Cassava Peel Hydrolysates for Single-cell Protein Production

Abstract: The growth of Candida utilis NRRL Y-1084 in acid and enzymatic hydrolysates of cassava peel and on glucose in a mineral salts medium was investigated in aerobic submerged cultivation. Kinetic and stoichiometric parameters for growth were determined. The cardinal temperatures of this yeast strain were 14 °C, 33 °C and 41 °C. C. utilis exhibited no absolute requirement for growth factors, although its maximum specific growth rate ( μ max ) was higher in the mineral salts medium with yeast extract than without, but its biomass yield coefficient (Y x/s ) did not differ much in these two media. In the enzymatic hydrolysate, its Y x/s value on sugar was 0.44 with a μ max of 0.35 h -1 , whereas the corresponding values were 0.52 and 0.48 h -1 in the acid hydrolysate and 0.50 and 0.37 h -1 in the mineral salts medium without yeast extract. The crude protein content of biomass grown in the glucose medium and the acid and enzymatic hydrolysates were 47.5%, 49.1% and 56.7%, respectivel y. The amino acid profile of th e yeast biomass compared favourab ly with the FAO standard. Cassava peel hydrolysate has potential as a cheap carbohydrate feedstock for the production of yeast sin gle cell protein by using

Yeast single cell protein in the diet of Oreochromis niloticus (L) fingerlings: An economic evaluation

Six isonitrogenous diets (30% protein) were prepared, D 0 , D IO , D 20 , D 30 , D 40 and D 50 . Diet Do the control diet) consist of fishmeal as the protein source. Diets D 10 to D 50 had fish meal replaced systematically with yeast single cell protein (SCP) in the order 10, 20, 30, 40 and 50%, respectively. Trial feeding was carried out with these feeds on Oreochromis niloticus . The cost benefit evaluation of these diets was carried out. Result showed that the 50% yeast SCP substituted diet had the lowest profit index, the, least expenditure as well as the best sales, net profit and cost-benefit ratio. Key word: microbial protein, Oreochromis niloticus , feeding, cost benefit, aquaculture.

English

An investigation was carried out on the possibility of replacing fishmeal with graded levels of yeast single cell protein (SCP; 10, 20, 30, 40 and 50%) in isonitrogenous feed formulations (30% protein) in the diet of&nbsp;Oreochromis niloticus&nbsp;fingerlings for a period of 12 weeks. The control diet had fishmeal as the primary protein source. There were six treatments and four replicates. The result indicates that the 50% yeast SCP diet gave the best in growth response with percentage weight gain (PWG) of 6.04, specific growth rate (SGR) of 0041, daily growth rate (DRG) of (0.0088) and feed conversion ratio (FCR) of 1.94. There was however no significant difference in growth parameters and feed conversion ratio between treatment (p &gt; 0.05). The proximate examination of the carcass composition of the whole fish body showed that the 50% yeast SCP fed fish had the highest percentage of body protein (55.35%), but with a lower amount of fat at the end of the feeding trial compared to the control. There was however no significant difference in carcass protein and fat content between treatments (p &gt; 0.05). It could therefore be concluded that yeast SCP can successfully replace fishmeal up to 50% level with 0.25% dietary methionine supplementation in a 30% protein diet for O.&nbsp;niloticus&nbsp;fingerlings with no significant difference in fish performance (p &gt; 0.05). &nbsp; Key words:&nbsp;Tilapia, yeast single cell protein, growth, carcass composition, feeding trials.

A conceptual lignocellulosic ‘feed+fuel’ biorefinery and its application to the linked biofuel and cattle raising industries in Brazil

It has been argued by some that the substitution of biofuels for gasoline could increase greenhouse gas (GHG) emissions, rather than reduce them. The increase is attributed to the indirect land use change effects of planting new grain and corn crops around the world to replace those progressively being devoted to ethanol production. In this paper, indirect effects are minimised by allowing land to be used for both food and fuel, rather than for one or the other. We present a sugarcane ‘feed+fuel’ biorefinery, which produces bioethanol and yeast biomass, a source of single-cell protein (SCP), that can be used as a high-protein animal feed supplement. The yeast SCP can partially substitute for grass in the feed of cattle grazing on pasture and thereby potentially release land for increased sugarcane production, with minimal land use change effects. Applying the concept conservatively to the Brazilian ethanol and livestock industry our model demonstrates that it would be technically feasible to raise ethanol production threefold from the current level of 27GL to over 92GL. The extra ethanol would meet biofuel market mandates in the US without bringing any extra land into agricultural or pastoral use. The analysis demonstrates a viable way to increase biofuel and food production by linking two value chains as called for by industrial ecology studies.

Yeast screening from avermectins wastewater and investigation on the ability of its fermentation

Wastewater from avermectin production is refractory with high output, high chemical oxygen demand (COD) concentration and high cost further. The current wastewater treatment technology, with little reuse of the organic material, needs high dilution ratio during treatment. Yeast single cell protein was produced from the wastewater of avermectins fermentation in this research. First, the yeast strain (H-1) which show enough tolerance to avermectins residue was screened from the wastewater, and it was identified as being most closely related to Candida tropicalis (100%, EF120592.1) using 18S rDNA gene sequence analysis. Second, its growth characteristics in the avermectins wastewater were studied. The dry biomass reached the maximal point of 10g/L, the COD removal was up to 66.67%, and avermectins removal in the wastewater was 99.48% at the optimal condition that it was liquid volume 50ml (250ml flask), pH 4.0, temperature 30°C, inoculum volume 10% (V/V) and fermentation period 20h. Third, the nutritional contents of dry yeast powder were determined, in which the water content was 8.12%, ash content was 5.18% and the crude protein was 40.02%. The dry yeast powder from avermectin waste liquor was promising to be used as a raw material or nitrogen source for commercial production of avermectins. The project was economically feasible by primary cost accounting.

Yeast Biomass Production in Brewery’s Spent Grains Hemicellulosic Hydrolyzate

Yeast single-cell protein and yeast extract, in particular, are two products which have many feed, food, pharmaceutical, and biotechnological applications. However, many of these applications are limited by their market price. Specifically, the yeast extract requirements for culture media are one of the major technical hurdles to be overcome for the development of low-cost fermentation routes for several top value chemicals in a biorefinery framework. A potential biotechnical solution is the production of yeast biomass from the hemicellulosic fraction stream. The growth of three pentose-assimilating yeast cell factories, Debaryomyces hansenii, Kluyveromyces marxianus, and Pichia stipitis was compared using non-detoxified brewery's spent grains hemicellulosic hydrolyzate supplemented with mineral nutrients. The yeasts exhibited different specific growth rates, biomass productivities, and yields being D. hansenii as the yeast species that presented the best performance, assimilating all sugars and noteworthy consuming most of the hydrolyzate inhibitors. Under optimized conditions, D. hansenii displayed a maximum specific growth rate, biomass yield, and productivity of 0.34 h(-1), 0.61 g g(-1), and 0.56 g l(-1) h(-1), respectively. The nutritional profile of D. hansenii was thoroughly evaluated, and it compares favorably to others reported in literature. It contains considerable amounts of some essential amino acids and a high ratio of unsaturated over saturated fatty acids.

Single-Cell Protein Diet of a Novel Recombinant Vitellogenin Yeast Enhances Growth and Survival of First-Feeding Tilapia (Oreochromis mossambicus) Larvae

Yeast single-cell protein (SCP) is a high-nutrient feed substitute. This study evaluates the dual applications of a novel recombinant Pichia pastoris SMD1168H (SMD) yeast, expressing a tilapia vitellogenin protein (rVtg), as an SCP diet for Artemia and the first-feeding fish larvae. Instar II Artemia fed rVtg, rVtg precultured in 5% fish oil (rVtg-FO), Saccharomyces cerevisiae (SC), or native SMD had greater lipid contents (P < 0.05) than the freshly hatched. Lipid deposition in the Artemia fed rVtg or rVtg-FO was greater (P < 0.05) than in those fed SMD or SC. Diet-induced accumulation of low levels of docosahexaenoic acid [22:6(n-3)] was detected only in Artemia fed the rVtg-based diets. Tilapia (Oreochromis mossambicus) larvae were fed solely yeast diets singly or in combination (d 3-22), or a staggered regimen of yeast (d 3-12) followed by unenriched or yeast-enriched Artemia (d 13-22). The larvae fed rVtg for 22 d increased in length and weight (P < 0.05), whereas those fed SC or SMD suffered growth suppression and high mortality. Such adverse consequences were ameliorated when 50% of SC was substituted with rVtg. The larvae prefed rVtg followed by a dietary switch to Artemia preenriched for 48 h with rVtg or rVtg-FO were greatest in length, had the highest weight gain, and lived the longest. Besides delivering rVtg protein, essential fatty acids and amino acids, rVtg may have probiotic effects in enhancing larval survival. This study suggests the feasibility of using the rVtg yeast as an Artemia booster and an SCP first feed for larvae.

Amino acid composition of yeast single cell protein grown on paneer whey

Etude des profils en aminoacides obtenus avec 3 souches de levure. Le lactoserum est clarifie par traitement thermique

A strain of Saccharomyces cerevisiae which grows efficiently on starch

Saccharomyces cerevisiae BRG 530 is a meiotic segregant of S. cerevisiae NCYC 361 (syn. Saccharomyces diastaticus ). While NCYC 361 grew poorly on soluble starch, BRG 530 utilized 62% of starch for growth in batch culture, yielding 0.86 g biomass (g starch used) −1 . In comparison, Lipomyces kononenkoae CBS 2514, which produces α-amylase (1,4-α- d -glucan glucanohydrolase, EC 3.2.1.1) in addition to glucoamylase (1,4-α- d -glucan glucohydrolase, EC3.2.1.3) and possesses debranching activities, utilized starch more completely (92%). However, with CBS 2514, the specific growth yield was lower than with BRG 530 at 0.65 g biomass (g starch used) −1 , and only 15% of L. kononenkoae biomass was protein compared with 41% for the S. cerevisiae strain. Therefore, even with incomplete utilization of substrate, BRG 530 was more efficient in producing yeast protein from starch. More complete (96%) utilization of starch by BRG 530 was achieved by adding α-amylase; this has little effect on the efficiency of substrate conversion to biomass. The properties of BRG 530 suggest that a strain of S. cerevisiae could be developed for the production of yeast single-cell protein or other growth-associated products from starchy substrates.

A strain of Saccharomyces cerevisiae which grows efficiently on starch

Saccharomyces cerevisiae BRG 530 is a meiotic segregant of S. cerevisiae NCYC 361 (syn. Saccharomyces diastaticus ). While NCYC 361 grew poorly on soluble starch, BRG 530 utilized 62% of starch for growth in batch culture, yielding 0.86 g biomass (g starch used) −1 . In comparison, Lipomyces kononenkoae CBS 2514, which produces α-amylase (1,4-α- d -glucan glucanohydrolase, EC 3.2.1.1) in addition to glucoamylase (1,4-α- d -glucan glucohydrolase, EC3.2.1.3) and possesses debranching activities, utilized starch more completely (92%). However, with CBS 2514, the specific growth yield was lower than with BRG 530 at 0.65 g biomass (g starch used) −1 , and only 15% of L. kononenkoae biomass was protein compared with 41% for the S. cerevisiae strain. Therefore, even with incomplete utilization of substrate, BRG 530 was more efficient in producing yeast protein from starch. More complete (96%) utilization of starch by BRG 530 was achieved by adding α-amylase; this has little effect on the efficiency of substrate conversion to biomass. The properties of BRG 530 suggest that a strain of S. cerevisiae could be developed for the production of yeast single-cell protein or other growth-associated products from starchy substrates.