Single‐cell protein production through microbial conversion of lignocellulosic residue (wheat bran) for animal feed

Agricultural residue (wheat bran) rich in carbohydrates was utilized in the fermentation process to produce microbial biomass. Single‐cell biomass consists of the dried cells of microorganisms, which are used as protein supplements in human food and in animal feed. In the present study, two different microorganisms (Candida utilis and Rhizopus oligosporus) were studied for biomass production. To enhance the nutritional contents of wheat bran, a number of different fermentation parameters (effect of inoculum size, age of inoculum, incubation period, moisture to substrate ratio and incubation temperature) were optimized. Maximum yield was obtained at an inoculum size of 10% (v/w), with the age of the inoculum being a 48 h old culture. A fermentation period of 48 h was found to give the maximum protein yield and viable counts of yeast cells and mould hyphae. The microorganisms showed good growth at 30 °C. After complete optimization of the fermentation parameters, a batch of wheat bran was fermented with C. utilis and R. oligosporus under the optimized conditions, resulting in a maximum crude protein yield of 41.02% compared with the 4.21% crude protein of the non‐fermented wheat bran. Copyright © 2015 The Institute of Brewing & Distilling     

Biochemical characteristics of tea fungus produced during kombucha fermentation

Tea fungus is symbiotic culture of acetic acid bacteria and yeasts, widely used to produce kombucha tea. Due to the rich biomass in tea fungus, it can be utilized as protein supplement in animal feed. The present study aimed to analyze the biochemical characteristics of tea fungus with the effect of fermentation time. Proximate, amino acids, and elemental analysis of tea fungus produced during kombucha fermentation were studied along with total count of microflora. Results suggested that tea fungus is rich in crude protein, crude fibre, and amino acid lysine. The biochemical characteristics of tea fungus studied were increased throughout the fermentation time.     

Fermented poultry litter and fungal enzyme supplementation of high-fibre broiler diets: Growth responses,carcass characteristics and blood lipids of fed chicks

Three different types of poultry litter, Broiler's (BL), Layer's (LL) and Grower's (GL), were subjected to fermentation by a mixed starter culture of Aspergillus niger, Leuconostoc spp. and Candida utilis for 108 h. Fermentation resulted in increase of crude protein, nitrogen free extract, calcium, phosphorus, biomass and amino acid content. The dried, highly fermented broilers litter was applied at 2 levels (0, 15%; w/w) as supplement of high-fibre basal diet along with different levels of fungal enzyme mixture (0, 1, 5, 10, 20 and 25 IU/kg diet) fed to 480 day-old broiler chicks of mixed sex in 2 trials conducted to study the growth responses and blood lipid composition of such birds to the diets. Results of these trials show a positive correlation between enzyme supplementation and body weight, feed efficiency, carcass weight, edible meat and the meat: bone ratio. Consistently significant reduction was observed in the blood total lipid, free fatty acid, phospholipid and cholesterol concentrations between the enzyme-deficient diet and the enzyme- and fermented poultry litter supplemented diet. However, from both trials it is concluded that an enzyme concentration of 15 IU/kg diet in the presence of 15% fermented poultry litter is best for supplementation.     

Production of value-added product from pineapple peels using solid state fermentation

Pineapple (Ananas comosus) peels are agricultural plant residues that contribute to waste disposal problem and there is little information on their conversion to useful products. Solid state fermentation (SSF) of pineapple peels (with and without ammonium sulphate) was done with a view to increase their protein content using Trichoderma viride ATCC 36316 for 96 h at 30 °C. The study was carried out using conical flasks and on-farm solid state fermenter. Chemical composition (fat, crude and true proteins, carbohydrate and ash) of the unfermented and fermented peels were determined using standard methods. Unfermented pineapple peel had low values of 4.5, 2.84, 0.6, 6.8% for crude protein, true protein, fat and ash contents, respectively. The SSF using T. viride with or without the addition of (NH₄)₂SO₄ increased the chemical compositions of the pineapple peels. Higher protein yields were recorded when (NH4)₂SO4 was used as nitrogen source. T. viride and (NH₄)₂SO₄ increased the crude protein content from 4.5 to 14.9% when fermentation was done using conical flask. With on-farm scale fermenter, protein yields increased further. SSF of pineapple peels with T. viride produced high protein fungal biomass and may be recommended as suitable for animal feed.     

Biomass composition of a Candida pseudotropicalis new strain grown on crude sweet whey

A yeast strain isolated from whey and named Candida LY 496 was grown continuously on crude sweet whey. The obtained biomass had a crude protein content of 47%. The amino acid composition was determined by high performance liquid chromatography (h.p.l.c). All essential amino acids were present and among them lysine was predominant (11.8%). The total nucleic acids of the biomass was 6.4%. Lipids represented 5% and the fatty acids 2% of the dry matter; 75% of the fatty acids were unsaturated, and linoleic acid constituted only 1% of the total fatty acids. Niacin and vitamin B₂ were the most abundant vitamins of the B group. Therefore Candida LY 496 biomass could be incorporated in animal food intakes.     

Growth of the Acid-Tolerant Fungus Scytalidium acidophilum as a Potential Source of Single-Cell Protein

An acid-tolerant fungus, Scytalidium acidophilum, was cultivated in peat extract for potential use as a single-cell protein (SCP) source. In shake flask fermentations with a 0.3% yeast extract diluted peat extract medium, it was found that the best conditions for growth occurred at pH 2.0 and 25°C. The maximum biomass concentration was produced after 10 days, with no significant differences for agitation rates between 100 and 200 rpm. Microbial contamination was not observed in nonaseptic operations. The protein content and amino acid composition of the mycelium produced compares with those reported for S. acidophilum grown in other fermentation media. The advantages of growing S. acidophilum in acid peat extract are presented.     

Effect of supplemental ram horn hydrolysate (RHH) at different levels on growth performance and slaughter traits of broilers

This study was carried out to determine the influence of ram horn hydrolysate (RHH) supplementation on the growth performance and slaughter traits of broilers. A total of 240 male broiler chicks (Ross 308), received from a commercial hatchery at 1 day of age, were allocated to four dietary treatments (H₀, H₁, H₂ and H₃ groups) in a completely randomized experimental design. Feed and water were offered ad libitum and lighting was continuous throughout the experimental period. The H₀ group was fed with basal diet plus normal drinking water. The H₁, H₂ and H₃ groups were fed with basal diet plus 1%, 2% and 3% RHH‐added water, respectively, in place of normal drinking water to meet the daily water requirements of broiler chicks from 1 to 28 days of age. All birds were housed in batteries from 1 to 21 days, and in grower broiler pens to 49 days. Feed intake and body weight gain were recorded weekly per pen. The average final body weights were 2524.9, 2601.2, 2441.7 and 2424.9 g for the H₀, H₁, H₂ and H₃ groups, respectively, and the difference was significant (P < 0.05). The average daily weight gains were 50.66, 52.25, 49.05 and 48.65 g, respectively, and the supplementation had no significant effect on this parameter. Daily feed consumptions were 96.18, 95.25, 91.70 and 90.75 g, respectively, and the difference between control and treatment groups was significant (P < 0.01). The feed conversion ratios (FCR) were, respectively, 1.79, 1.71, 1.73 and 1.81 (P > 0.05). At the end of the trial all birds were slaughtered to determine the slaughter traits. The hot carcass weights and yields were 1874.0, 1934.7, 1767.0, 1845.3 g and 75.78, 77.80, 75.00, 77.41%, respectively, and the difference was significant (P < 0.01). In addition, offal weights were determined and it was observed that there was no difference among the groups. Abdominal fat pad weights were similar in all groups. The H₁ group experienced more effects on some performance and slaughter traits than the control and the other RHH‐treated groups, and the supplementation of diets with RHH at a level of 1% improved broiler performance. Copyright © 2005 Society of Chemical Industry     

Identification and proteomic analysis of a novel gossypol-degrading fungal strain

BACKGROUND: Cottonseed meal, an important source of feed raw materials, has limited use in the feed industry because of the presence of the highly toxic gossypol. The aim of the current work was to isolate the gossypol‐degrading fungus from a soil microcosm and investigate the proteins involved in gossypol degradation. RESULTS: A fungal strain, AN‐1, that uses gossypol as its sole carbon source was isolated and identified as Aspergillus niger. A large number of intracellular proteins were detected using sodium dodecyl sulfate–polyacrylamide gel electrophoresis, but no significant difference was observed between the glucose‐containing and gossypol‐containing mycelium extracts. Two‐dimensional gel electrophoresis results showed that the protein spots were concentrated in the 25.0–66.2 kDa range and distributed in different pI gradients. PDQuest software showed that 51 protein spots in the gels were differentially expressed. Of these, 20 differential protein spots, including six special spots expressed in gossypol, were analyzed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. CONCLUSION: The fungus AN‐1 biodegraded gossypol and the proteomic analysis results indicate that some proteins were involved in the gossypol biodegradation during fungus survival, using gossypol as its sole carbon source. Copyright © 2011 Society of Chemical Industry     

Mathematical model for Phaffia rhodozyma growth using peat hydrolysates as substrate

The potential of peat hydrolysates for the production of astaxanthin from Phaffia rhodozyma yeast biomass in continuous fermentation was studied. Chemostat fermentations of the yeast were performed using peat hydrolysates as substrate. Kinetic parameters were calculated for the growth of the yeast and the biomass productivity was determined using mathematical models. A low maximum specific growth rate (μ_max=0·08 h⁻¹) and a high Monod constant (Ks=26·2×10³) were obtained for this substrate. The low maintenance energy requirement found, 0·020 g (gh)⁻¹, confirms the aerobic metabolism of the yeast with this substrate. Under selected conditions, a biomass productivity of 0·108 g (lh)⁻¹ and an astaxanthin productivity of 0·046 mg (lh)⁻¹ were obtained. The biomass produced had a high protein and astaxanthin content (490±8 g kg⁻¹ and 0.43±0.07 g kg⁻¹, respectively), indicating that it can be used as a feed additive. © 1998 SCI.     

Recovery of residual nutrients from agri-food byproducts using a combination of solid-state fermentation and insect rearing

The present research develops an innovative nutrient recovery strategy for capturing of un-utilised nutrients from agri-food byproducts using a combination of solid state fermentation (SSF) and insect rearing. SSF of borage and flaxseed meals were performed using GRAS organisms to release indigenous nutrients and to produce additional nutrients. Proximate analysis of the SSF-meals showed increases in both lipid and protein contents. Black soldier fly larvae (BSFL) were then grown on these SSF-meals for 12 day. The meals fermented singularly with Lactobacillus plantarum or Aspergillus niger displayed up to 30% enhancement in BSFL biomass, and dual fermentation with L. plantarum and Aspergillus oryzae resulted in an additional 10% enhancement. These examinations showed SFL use over-90% of proteins and lipids in SSF-meals. The results indicate that fermentation of these low-value meals can boost the efficacy of larval growth and the recovery of nutrients from agricultural byproducts as larval biomass.     

Production of Single Cell Protein from Cassava Starch in Air-lift Fermenter by Cephalosporium eichhorniae

Batch and continuous cultivations were used to investigate the single cell protein (SCP) production by Cephalosporium eichhorniae 152 in an air-lift reactor. The fungus was grown in an 8L air-lift fermenter. The culture medium consisted of cassava as a sole-carbon source, (NH₄)₂SO₄ as a nitrogen source and KH₂PO₄ as a buffering agent. The pH of the medium was adjusted to 3.8 and was controlled during fermentation by using an automatic pH-controller via 0.5 N NaOH. In batch fermentation, 1% of cassava gave the highest yield of 0.4. The optimum condition for continuous fermentation was 1% cassava in feed medium at a dilution rate of 0.4 h^-1 (396 ml/h where 0.35 was the final yield. The productivity of continuous culture was found to be higher than that of the batch culture (0.135 g/l.h versus 0.04 g/lh).     

Glucoamylase Biosynthesis by Cells of Aspergillus niger C58-III Immobilized in Sintered Glass and Pumice Stones

A simple method of A. niger C_58-III cell immobilization is described. This strain produces extracellular glucoamylase. According to the proposed method A. niger spores were first immobilized by adsorption in sintered glass Rasching rings (RR) or pumice stones (PS). Growing out from spores, A. niger cells produced extracellular glucoamylase. This technique facilitates the culture growth in a filamentous spongy structure of the supports with a continuous accumulation of biomass. After every 24 h it was possible to obtain culture liquid rich in glucoamylase. This procedure can be repeated 30 times using the same sample of immobilized A. niger culture without any loss of glucoamylase activity in the liquid medium. In a 96 h period immobilized A. niger cells produced 300 units × ml⁻¹ whereas a shake culture of this fungus produced only 186 units × ml⁻¹.     

Production,partial purification and properties of β‐mannanases obtained by solid substrate fermentation of spent soluble coffee wastes and copra paste using Aspergillus oryzae and Aspergillus niger

In order to achieve a higher added value of two galactomannan‐containing wastes, copra paste and spent coffee from the soluble coffee industry (SCW), solid substrate fermentation (SSF) was used. Filamentous fungi Aspergillus oryzae and A niger were used to evaluate the feasibility of producing β‐mannanase by SSF. A 2³ factorial design was used to select the best interaction among the two fungi, the two substrates and two fermentation times. The treatment ‘A niger–copra–2.5 days’ produced a significantly higher (p < 0.05) β‐mannanase activity, having five different isoforms of the enzyme, one of which was partially purified to a specific activity of 764 U mg⁻¹ (U = nmol of mannose released per second from a galactomannan substrate). Copra paste had a higher mannose/galactose ratio (14:1) than SCW (6:1), and low oil content, which led to higher β‐mannanase production from SSF. A β‐mannanase from SSF of copra produced by A oryzae was highly purified using acetone precipitation and cation exchange and size exclusion chromatographies. This enzyme had an MW of 110 kDa, a pI between 3.5 and 4.5 and a specific activity of 1760 U mg⁻¹; purification achieved was 90.7 times. The temperature and pH for optimal activity were 40 °C and 6.0 respectively. The optimal temperature was lower and the optimal pH higher than others previously reported (produced by submerged fermentation), which could be important for viscosity reduction of concentrated coffee extract in instant coffee manufacture. Copra is an interesting alternative for β‐mannanase production, since it is readily available in Mexico; moreover, the residue after SSF has a reduced galactomannan content and may be used for monogastric animal feed. © 2000 Society of Chemical Industry     

Rheological Studies During Submerged Citric Acid Fermentation by Aspergillus niger in Stirred Fermentor Using Apple Pomace Ultrafiltration Sludge

Rheological profile studies for apple pomace ultrafiltration sludge (APS) broth with filamentous fungus, Aspergillus niger NRRL-567 during citric acid (CA) fermentation are reported for the biomass developed in a 7.5 l bench scale fermentor. CA bioproduction of 23.67?±?1.0 g/l APS and 40.34?±?1.98 g/l APS was obtained in control (120 h) and in treatment with inducer, MeOH 3% (v/v), respectively, after 132 h of fermentation by A. niger NRRL 567. The rheological properties of the fermentation broth including pellets were analyzed. The control demonstrated non-Newtonian pseudoplastic behaviour due to more filamentous growth. However, in treatment supplemented with inducer (methanol), pellet form was observed during fermentation with less viscous non-Newtonian broths. The power law model was followed with good confidence of fit (77.8–88.9%) throughout the fermentation in treatment with MeOH as an inducer. However, power law was followed with moderate fit of confidence (65.3–75.9%) at the beginning of fermentation until 48 h and later followed a good confidence of fit (75.9–88.2%) until 144 h of fermentation in control. Important rheological changes occurred in the broth during maximal CA production phase along with increase in biomass in the pelleted mycelium form.     

Comparative study of proximate composition and amino acid in farmed and wild Pseudobagrus ussuriensis muscles

The proximate composition and amino acid compositions of the muscle of wild and farmed Pseudobagrus ussuriensis were compared. The lipid content of the farmed fish was significantly higher, while moisture content was significantly lower, than those of the wild fish. Pseudobagrus ussuriensis protein has a well‐balanced amino acid composition. The percentages of total amino acids, essential amino acids, nonessential amino acids and delicious amino acids were significantly higher in the wild than those in farmed fish. The ratios of W_EAA to W_TAA (42.78%–43.02%) and W_EAA to W_NEAA (85.52%–87.74%) were comparable to the reference values of 40% and above 60% recommended by FAO/WHO. According to the amino acid scores, methionine would have been described as the first limiting amino acid, and Lys had the highest score for the protein in both wild and farmed Pseudobagrus ussuriensis. This study shows that Pseudobagrus ussuriensis under investigation have high nutritional qualities and are good protein resources.     

Effect of fungal damage by Fusarium spp and Diaporthe/Phomopsis complex on protein quantity and quality of soybean seed

Seeds from three soybean genotypes were tested to evaluate the effect of fungal damage by Fusarium spp and Diaporthe/Phomopsis complex on protein quantity and quality. Fungus‐infected seeds had higher protein contents than uninfected ones. A selective degradation of soluble proteins was detected in seeds infected with either fungus. Some of the storage proteins degraded were identified as α′, α and β subfractions of the β‐conglycinin, and A₃ subfraction of the glycinin. Furthermore, reductions in lipoxygenase and trypsin inhibitor activities were observed in fungus‐infected seeds. Amino acid composition did not vary between infected and uninfected seed lots, so protein degradation should not affect amino acid structures. Copyright © 2004 Society of Chemical Industry     

Breaking of structural dormancy in seeds of Tetrapleura tetraptera by Aspergillus niger

Aspergillus niger (strain UUF9202) significantly reduced the dormancy period and boosted aggregate germination percentage (AGP) in seeds of Tetrapleura tetraptera. A net reduction in mean germination time (MGT) to 12 days and an increase from 0 to 42% AGP were obtained in 32 days. The optimal spore inoculum of the fungus was 8.5 × 10≥10 ml^?1 per 100 seeds in 96 h pregermination incubation. The potential of some physical factors in combination with this fungal concentration in enhancing AGP was evaluated. The treatments were as follows: (i) hot water scarification at 30°C, 50°C, 80°C and 100°C plus A niger; and (ii) nicking by decoating at either the micropylar or chalazal ends plus A niger. Micropylar scarification plus A niger gave the highest AGP (94%) followed by chalazal scarification plus A niger (86%) and hot water dip at 80°C + A niger (82%). The control seeds which were soaked in presterilised (by autoclaving at 121°C for 15 min) A niger spore suspension at 30°C gave zero germination.     

Production of Candida utilis biomass as aquaculture feed

Fish offal-peat compost was hydrolysed and the resultant liquid extracts used as substrate in the cultivation of the yeast Candida utilis. The yeast was able to grow in this culture medium, attaining a growth yield of approximately 260 g biomass kg^?1 total carbohydrate consumed. The biomass produced had a good amino acid composition, with a protein content of 520 g kg^?1, and a relatively low lipid content. Dry yeast was used as a feed component in the diet of cultivated rainbow trout (Oncorhynchus mykiss) in which it substituted well for other, traditional sources of protein.     

Nutritional evaluation of the fungus Phycomyces blakesleeanus as a protein source

The quality of the protein of the carotenogenic fungus Phycomyces blakesleeanus Burgeff, strain NRRL 1555 ( - ), was evaluated with rats and observed to have a protein efficiency ratio of 1.4. The limiting amino acids were tryptophan, sulphur-containing amino acids, lysine and isoleucine. Upon incorporation into diets containing 100 g kg⁻¹ protein the proportions of the above mentioned amino acids of the optimal recommended dietary allowances for growing rats were 33.0%, 57.4%, 74.5% and 87.2% respectively. Furthermore, the fungal protein was found to contain an excess of histidine about eight fold more than the recommended dietary allowance for growing rats. Some safety aspects were examined and, although the fungus was consumed in high dietary concentrations, 242 g kg⁻¹ of the diet, no pronounced toxicological effects were observed.     

Improving the performance of industrial ethanol‐producing yeast by expressing the aspartyl protease on the cell surface

The yeasts used in fuel ethanol manufacture are unable to metabolize soluble proteins. The PEP4 gene, encoding a vacuolar aspartyl protease in Saccharomyces cerevisiae, was either secretively or cell‐surface anchored expressed in industrial ethanol‐producing S. cerevisiae. The obtained recombinant strains APA (expressing the protease secretively) and APB (expressing the protease on the cell wall) were studied under ethanol fermentation conditions in feed barley cultures. The effects of expression of the protease on product formation, growth and cell protein content were measured. The biomass yield of the wild‐type was clearly lower than that of the recombinant strains (0.578 ± 0.12 g biomass/g glucose for APA and 0.582 ± 0.08 g biomass/g glucose for APB). In addition, nearly 98–99% of the theoretical maximum level of ethanol yield was achieved (relative to the amount of substrate consumed) for the recombinant strains, while limiting the nitrogen source resulted in dissatisfactory fermentation for the wild‐type and more than 30 g/l residual sugar was detected at the end of fermentation. In addition, higher growth rate, viability and lower yields of byproducts such as glycerol and pyruvic acid for recombinant strains were observed. Expressing acid protease can be expected to lead to a significant increase in ethanol productivity. Copyright © 2010 John Wiley & Sons, Ltd.