Inoculation Amount Research Articles

Synergistic Effect of the Lactic Acid Bacteria and Salt Coagulant in Improvement of Quality Characteristics and Storage Stability of Tofu.

In this study, a new way to produce tofu with lactic acid bacteria (Lactobacillus casei, L. casei) and salt coagulant (magnesium sulfate) has been developed and optimized in order to improve the quality characteristics and the storage stability. Processing parameters (bean-water ratio, inoculation amount, magnesium sulfate concentration and pressing time) of tofu were studied. Yield, water holding capacity (WHC), texture and sensory were measured for evaluating quality characteristics of tofu. Based on the single factor and response surface methodology (RSM), the optimized conditions of tofu were determined as follows: bean-water ratio was 1:4 g/mL, fermentation time was 5 h at 37°C when the inoculation amount was 4.0%, magnesium sulfate concentration was 2.0 mol/L and pressing time was 1 h. Under the optimum conditions, the yield of the tofu was 140.45 g, the WHC was 87.25 %, the hardness was 420.36 g, and the tofu had better sensory characteristics, soft, uniform texture, as well as good flavor. The shelf life and stability of tofu during storage were also evaluated under the optimum conditions. The results showed that fermented tofu had a longer shelf life than unfermented tofu at room temperature. Compared with the "pasteurization + low temperature" group and "low temperature" group, the fermented tofu in the "microwave + low temperature" group had a longer shelf life and better-quality properties during storage. Tofu, prepared by the lactic acid bacteria fermentation and salt coagulant, would be accepted as a new type of tofu according to its quality characteristics and storage stability.

Statistical optimization of simultaneous saccharification fermentative hydrogen production from corn stover

ABSTRACT Corn stovers are rich in carbohydrates and can be used by anaerobic bacteria to produce hydrogen by fermentation. In the present study, using hydrogen production as the main experimental index, the effect of different influential factors on hydrogen production from corn stover saccharification and fermentation was studied, using the response surface method BBD model. The significance of interactions between different influential factors on hydrogen production by simultaneous saccharification and fermentation of corn stover material were investigated and optimized. Results showed that there were several factors affecting simultaneous saccharification fermentative hydrogen production from corn stover, including substrate concentration, inoculation amount, pH value and enzyme concentration. In linear terms, substrate concentration had the greatest influence on hydrogen production by anaerobic simultaneous saccharification and fermentation. In terms of multi-factor interactions, the interaction between pH and enzyme concentration was the most significant. The optimal hydrogen production conditions established from the BBD model were as follows: substrate concentration of 25 mg/mL, inoculation amount proportion of 32.62%, initial pH value of 6.50 and enzyme concentration of 172.08 mg/g, resulting in the maximum hydrogen production of 55.29 mL/g TS. The actual maximum hydrogen production reached 56.66 mL/g TS, with these experimental results consistent with the predicted value established from equation fitting. This study provides a reference for hydrogen production by anaerobic synchronous saccharification fermentation using corn stover as substrate and lays a foundation and provides technical support for the industrialization of biological hydrogen production using corn stover as substrate.

Screening of bacterial strains from the gut of Pacific White Shrimp (Litopenaeus vannamei) and their efficiencies in improving the fermentation of soybean meal.

Microbial fermentation is an efficient, economical and eco-friendly approach to overcome the limitations in soybean meal replacement of fish meal in aquaculture. However, little research focused on the development of shrimp-derived strains for fermentation of SBM. In this study, Bacillus sanfensis (SQVG18) and Bacillus stratosphericus (SQVG22) were screened from shrimp intestine for fermentation according to the activities of protease, cellulase and phytase. The optimized fermentation conditions of SQVG18 and SQVG22 were as follow: fermentation temperature (40°C vs 35°C), fermentation time (48hboth), inoculation amount [4% both (v/m)], solid-liquid ratio [1:1.2vs 1:1 (g/ml)]. After 48 hfermentation, SQVG18 and SQVG22 increased crude protein content by 6.93% and 5.95%, respectively; degraded most of macromolecular proteins to micromolecular proteins (< 20kDa); improved amino acids profiles, like lysine and methionine in particular; significantly decreased the anti-nutritional factors such as trypsin inhibitor, glycinin and β-conglycinin (P<0.05). In addition, both strains were observed no hemolytic activity, less antibiotic resistance genes and definite inhibition to common shrimp pathogens of Vibrio alginolyticus sp. and Vibrio parahaemolyticus sp. These results indicated that both strains could improve nutrition values of soybean meal effectively and have potential applications in shrimp culture.

Isolation, Kinetics, and Performance of a Novel Phenol Degrading Strain

Efficient phenol-degrading bacteria is still the key to the biological treatment of phenol-containing wastewater. In this research, a novel phenol-degrading strain N8 was isolated. According to the 16S rDNA identification, it was concluded that the N8 strain was Bacillus sp. IARI-J-20. The wastewater treatment experiments showed that the phenol degrading rate of N8 reached 92.8 % at 24 h with the inoculation amount of 15 %, temperature of 30 °C, pH of 7.2, yeast extract addition of 0.08 %, and initial phenol concentration of 225 mg L–1. Haldane’s model was fit for the growth kinetics of the phenol-degrading strain N8 over a wide range of initial phenol concentrations (50–1200 mg L–1), with kinetic values μmax = 0.33 h−1, Ks = 79.16 mg L–1, and Ki = 122 mg L–1. The yield coefficient reached maximal value when the phenol concentration was 400 mg L–1. When the initial phenol concentration was more than 400 mg L–1, the inhibition effect of phenol became predominant.

Production and characterization of a novel alkaline protease from a newly isolated Neurospora crassa through solid-state fermentation

Microbial proteases are widely used to prepare protein hydrolysates with health-promoting biopeptides. Here, a newly isolated strain of Neurospora crassa (named as CGMCC3088) was used to produce proteases through solid-state fermentation of okara as the substrate. The optimal fermentation conditions are: okara, 10 g; water, 21 mL; initial pH, 5.0; incubation temperature, 30 °C; inoculation amount, 2 mL; fermentation time, 72 h, with a corresponding protease activity of 1959.82 U/g. The protease was further purified by ammonium sulphate precipitation, followed by ion-exchange chromatography on DEAE-Sepharose and Sephadex G-75. The molecular weight of the protease was 30 kDa, and further mass spectrometry analysis clearly indicated that it was a novel protease. The protease had the optimal activity at 55 °C and pH 9. The enzyme activity was partially inhibited by SDS and metal ions, whereas little affected by organic solvents. The protease was completely inactivated by phenylmethylsulfonyl fluoride, indicating its dominant serine protease activity. The enzyme preferably hydrolyzed casein, and kinetic analysis showed that its Km and Vmax were 2.18 mg/mL and 36.36 μg/mL/min, respectively. Therefore, Neurospora crassa CGMCC3088 has the potential to produce a novel organic solvent-stable alkaline protease, which may be applied to the preparation of bioactive ingredients.

Production of theophylline via aerobic fermentation of pu-erh tea using tea-derived fungi

BackgroundCaffeine is one of the most abundant methylxanthines in tea, and it remains stable in processing of general teas. In the secondary metabolism of microorganism, theophylline is the main conversion product in caffeine catabolism through demethylation. Microorganisms, involved in the solid-state fermentation of pu-erh tea, have a certain impact on caffeine level. Inoculating an appropriate starter strain that is able to convert caffeine to theophylline would be an alternative way to obtain theophylline in tea. The purpose of this study was to isolate and identify the effective strain converting caffeine to theophylline in pu-erh tea, and discuss the optimal conditions for theophylline production.ResultsCaffeine content was decreased significantly (p < 0.05) and theophylline content was increased significantly (p < 0.05) during the aerobic fermentation of pu-erh tea. Five dominant fungi were isolated from the aerobic fermentation and identified as Aspergillus niger, Aspergillus sydowii, Aspergillus pallidofulvus, Aspergillus sesamicola and Penicillium mangini, respectively. Especially, A. pallidofulvus, A. sesamicola and P. mangini were detected in pu-erh tea for the first time. All isolates except A. sydowii TET-2, enhanced caffeine content and had no significant influence on theophylline content. In the aerobic fermentation of A. sydowii TET-2, 28.8 mg/g of caffeine was degraded, 93.18% of degraded caffeine was converted to theophylline, and 24.60 mg/g of theophylline was produced. A. sydowii PET-2 could convert caffeine to theophylline significantly, and had application potential in the production of theophylline. The optimum conditions of theophylline production in the aerobic fermentation were 1) initial moisture content of 35% (w/w), 2) inoculation quantity of 8%, and 3) incubation temperature at 35 °C.ConclusionsFor the first time, we find that A. sydowii PET-2 could convert caffeine to theophylline, and has the potential value in theophylline production through aerobic fermentation.

Effects of biomass and environmental factors on nitrogen removal performance and community structure of an anammox immobilized filler

In order to reduce the loss of anaerobic ammonia oxidation (anammox) sludge and stabilize the reaction microenvironment, polyvinyl alcohol - polypropylene (PVA-PP) was used to encapsulate anammox bacteria on a filler. The influence of different inoculation amounts (2, 4, 6 and 8%) on the overall nitrogen removal process was first compared and then the anammox characteristics of the immobilized filler under the influence of different environmental factors were evaluated through batch experiments. The results show that the biomass only affected the growth rate of the activity during the logarithmic phase, while the total nitrogen removal rate (NRR) tended to be similar after 99 d of culture. The NRR reached 1.83 kg·(m3·d)-1 on day 140, which was 9.4 times that of suspended sludge before encapsulation, and the structure of embedding filler was complete without shedding. Scanning electron microscopy (SEM) showed that the internal porous network structure formed channels and a large number of anammox bacteria were observed around. Microbial community analysis of the 16S rDNA gene showed that the diversity was maintained in the entrapped carrier. Furthermore, the effective enrichment of the anammox functional bacteria Candidatus Kuenenia (AF375995.1) increarsed from 11.06% to 32.55%. The PVA-PP immobilized filler fit well with the biological nitrogen removal kinetic model and could also achieve coupling of anammox and denitrification. The inhibition effect of the organic carbon source interference and starvation on anammox bacteria was significantly weakened.

A New Strain of Bacillus tequilensis CGMCC 17603 Isolated from Biological Soil Crusts: A Promising Sand-Fixation Agent for Desertification Control

In arid and semi-arid desert ecosystems, physical, chemical, and vegetative measures were used to prevent wind erosion. However, studies on the utilization of microbial resources for sand fixation are still limited. To fill this gap, a new strain of Bacillus tequilensis CGMCC 17603 with high productivity of exopolysaccharide (EPS) was isolated from biological soil crusts, and its high-density culture technology and sand-fixing ability were studied. The one-factor-at-a-time approach (OFAT) and Box–Behnken design of CGMCC 17603 showed that the optimum culture conditions were pH 8.5, temperature 31 °C, agitation speed 230 rpm, and inoculation quantity 3%, and the optimum medium was 27.25 g/L glucose, 15.90 g/L yeast extract, and 5.61 g/L MgSO4•7H2O. High-density culture showed that the biomass and EPS yield of CGMCC 17603 increased from 9.62 × 107 to 2.33 × 109 CFU/mL, and from 8.01 to 15.61 g/L, respectively. The field experiments showed that CGMCC 17603 could effectively improve the ability of sand fixation and wind prevention. These results indicated that B. tequilensis, first isolated from cyanobacterial crusts, can be considered as an ideal soil-fixing agent to combat desertification in arid and semi-arid areas.

Biohydrogen production from Humulus scandens by dark fermentation: Potential evaluation and process optimization

As a perennial grass, Humulus scandens is rich in cellulose which can be fermented for bioenergy producing. Hence, the hydrogen production potential of the Humulus scandens from dark fermentation by Enterobacter aerogenes was investigated in this paper. Cellulase amount, inoculation amount, and initial pH value were evaluated. The interrelationship between these factors were studied by Response Surface Box-Behnken Experiments. Results showed that there was a significant correlation between the three factors. Through the correction of the regression equation, the optimized technological conditions were obtained. The amount of cellulase was 0.203 g g−1 TS, the inoculation amount was 42.6%, the initial pH value was 6.59, the pre-estimated maximum cumulative value of hydrogen production was 65.12 mL g−1 TS, and it was similar to the test mean value which was 64.08 mL g−1 TS.

Stimulatory effects of rhamnolipid on corncob residues ethanol production via high-solids simultaneous saccharification and fermentation

In this study, the feasibility of rhamnolipid-assisted high-solids simultaneous saccharification and fermentation (SSF) of unwashed corncob residues and the process of rhamnolipid action was investigated. The effects of enzyme dosage (5–15 FPU/g-cellulose), inoculation amount (4–12 g/L), and rhamnolipid concentration (0.2–4 g/L) on ethanol production were evaluated. The ethanol yield at 20% (w/w) solids loading and 10 FPU/g-cellulose enzyme dosage increased to 61.99% by adding 0.2 g/L rhamnolipid, which was 22.39% higher than that produced from the control sample with 10 FPU/g-cellulose, and was close to the ethanol yield of the control sample (61.32%) with 15 FPU/g-cellulose. However, adding rhamnolipid at a high dosage (>2 g/L) led to sugar accumulation and negative effects on yeast growth. A schematic showing how rhamnolipid enhancement influences the high-solids SSF revealed that: i) Adding rhamnolipid to the fermentation medium reduced the surface tension of the SSF system; ii) Rhamnolipid accumulated at the interface between the two phases and reduced the level of deactivation of cellulase; and iii) X-ray photoelectron spectroscopy spectra analyses revealed that rhamnolipid addition efficiently reduced the adsorption of the enzyme on fermentation residues. The addition of rhamnolipid is an effective strategy to enhance ethanol production from corncob residues, even without pretreatment.

Biodegradation kinetics of microcystins-LR crude extract by Lysinibacillus boronitolerans strain CQ5

As the most common variant of microcystins (MCs), microcystin-LR (MCLR) is a kind of toxins produced by some species of harmful cyanobacteria and more and more attention has been paid to it. Biodegradation has been extensively investigated and recognized to be a cost-efficient and environmentally benign method for MC clean-up. In order to further research the growth characteristics of strain and the biodegradation characteristics of MCLR, it is necessary to use the dynamic mathematical models as powerful and useful tools. In this study, strain CQ5 was screened and identified by morphological observation, physiological and biochemical tests, and 16S rDNA sequence analysis. The kinetic models of cell growth and MCLR degradation were established with the Gompertz model and revised Monod kinetic model. The results showed that strain CQ5 had the closest phylogenetic similarity to Lysinibacillus boronitolerans (T-10a, AB199591) in the phylogenetic tree, with 99% bootstrap support. Strain CQ5 could utilize MCLR as the carbon and nitrogen source for growth. When the initial pH value was 7 and the inoculation amount was 3%, strain CQ5 grew well in MSM, in which the MCLR crude extract was used as the carbon and nitrogen source of strain CQ5. Within 244 h, the MCLR concentration changed from 14.12 to 1.57 μg/L and its degradation rate could reach 88.88%. The growth curve fitted with the Gompertz growth model (Nt = 1.3119 * exp(−0.1237 * exp(−6.6341t)), R2 > 0.99). The process of MCLR degradation agreed with the first-order reaction kinetic equation (lnS = 2.64764 − 0.01537t, R2 > 0.99). The linkage relationship between MCLR concentration, cell density, and MCLR degradation rate was consistent with the revised Monod equation (V = 0.342S, R2 > 0.97) at low substrate concentration, where Vmax/ Ks was 0.342. The dynamic relationship in which strain CQ5 degraded MCLR and used it as the carbon and nitrogen source to promote its own growth could be explained by the equation S = 14.12 e− 0.342 Nt (N = 1.08). The growth of strain CQ5 and MCLR concentration in degradation system could be simulated and predicted by the dynamic mathematical models in this study. And the predicted results were very consistent. These results could provide theoretical reference for studying the mechanism of MCLR biodegradation and promote the engineering application of strain CQ5.

Retracted: Development of Bulk Metallic Glasses and their Composites by Additive Manufacturing – Evolution, Challenges and a Proposed Novel Solution

Bulk metallic glasses (BMGs) and their composites (BMGMCs) have emerged as competitive materials for structural engineering applications exhibiting superior tensile strength, hardness along with very large elastic strain limit. However, they suffer from lack of ductility and subsequent low toughness due to the inherent brittleness of the glassy structure which makes them amenable to failure without appreciable yielding. Various mechanisms and methods have been proposed to counter this effect out of which, recently Additive Manufacturing has gained widespread attention. It is proposed that additive manufacturing can overcome these difficulties in single step due to inherent existence of very high cooling rate in the process which is essential for glass formation. This, when coupled with careful selection of alloy chemistry is proposed to be the best solution to fabricate near net shape parts in a single step with excellent properties. In this report, an effort has been made to describe one possible route to achieve this. Solidification processing employing carefully selected inoculants based on edge to edge matching technique along with the carefuly controlled inoculation procedure is proposed to reflect upon enhanced mechanical properties. It is hypothesized that number density, size and distribution of ductile crystalline phase would best be able to improve microstructure and hence properties. This is meant to be controlled by manipulating type, size and the amount of inoculants. The proposed methodology is claimed to bear maximum potential.

Screening of a pyrene-degrading bacterium and its degradation effect on polycyclic aromatic hydrocarbons oxidation

Enrichment culture method, A highly efficient functional bacterium B4 was isolated from polycyclic aromatic hydrocarbon contaminated soil by gradient domestication with pyrene as a single carbon source. The bacterium has strong tolerance to high concentration of polycyclic aromatic hydrocarbons and good degradation ability in a certain concentration range. The degradation rate of pyrene by the strain was 85% under the condition of pyrene concentration of 100 mg/L and inoculation amount of 5%. The degradation effects of the strain on polycyclic aromatic hydrocarbons (PAHs) such as fluorene, naphthalene, fluoranthene and phenanthrene were also investigated. The results showed that the strain B4 had good broad-spectrum degradation performance for PAHs.

Isolation and characterization of heterotrophic nitrifying bacteria and the removal of pollutants in black and malodorous water bodies

Aiming at the problem of high concentration of COD and NH3-N in black and odorous water bodies, heterotrophic nitrifying bacteria which can remove ammonia nitrogen and organic pollutants were screened out in the laboratory simultaneously. A heterotrophic nitrifying functional group was constructed by using the strategy of bacterial source reorganization ecologically, and the removal effect of heterotrophic nitrifying functional bacteria on organic pollutants and ammonia nitrogen in water was studied. The results showed that the removal rate of ammonia nitrogen in the water was more than 52%, and the removal rate of COD was 57%∼86%. The effect of heterotrophic nitrifying functional bacteria group 1 on the removal of COD and ammonia in water was better, and the removal rate was 76.5% and 54.8%, respectively. The optimum inoculation test showed that the optimum inoculation amount of the heterotrophic nitrification bacteria group 1 was 10 ppm.

Application of Agaricus bisporus industrial wastewater to produce the biomass of Pichia burtonii.

By using Plackett-Burman combined with Box-Behnken design, the fermentation conditions of Pichia burtonii using Agaricus bisporus industrial wastewater as culture medium were optimized. The biomass of P. burtonii in the fermentation broth was analyzed by multispectral imaging flow cytometry. Plackett-Burman design was used to screen out three factors from six factors affecting the biomass of P. burtonii as major factors. The Box-Behnken response surface method was used to optimize the interaction of the three main factors to predict the optimal fermentation conditions. The significant factors affecting the biomass of P. burtonii, such as shaking speed, solubility and culture temperature, were screened. The optimum conditions for P. burtonii were as follows: a shaking speed of 265 rmp, a solubility of 8%, a culture temperature of 25 °C, an initial pH of 6.0, an inoculation amount of 8%, and an amount of 30 mL liquid in 250 mL, and the total living yeast can reach 1.27 ± 0.02 × 108 Obj/mL, which was within the 95% confidence interval of the predicted model (1.08-1.32 × 108 Obj/mL).

Ethanol production by simultaneous saccharification and cofermentation of pretreated corn stalk.

The recalcitrance of lignocellulosic biomass is a major factor limiting its conversion into biofuels. Therefore, in this study, we pretreated corn stalk with 2% Na2 CO3 and 2% H2 O2 for time 70 min at 130°C using a corn stalk to liquid ratio of 1:10. The fermentation broth from multicopy Saccharomyces cerevisiae strains engineered for lignocellulase synthesis was used to enzymatically hydrolyze the pretreated corn stalk. The highest monosaccharide yield (102 mmol/L) was obtained using 15 IU endocellulase, 10 IU exocellulase, and 15 IU β-glucosidase per gram of cellulose and 20 IU xylanase per gram of hemicellulose. Subsequently, the high-efficiency ethanol-producing S. cerevisiae strain WXY12, which can produce ethanol from glucose and xylose simultaneously, was added to the fermentation system. The entire process involved ethanol production through simultaneous saccharification and fermentation (SSF). Optimization of the fermentation conditions (yeast powder as a nitrogen source, temperature of 30°C, MgSO4 as a metal ion inducer, rotation speed of 180 rpm, solid-liquid ratio of 1:8, and inoculation amount of 2%) resulted in an ethanol output of 46.87 g/L and a theoretical conversion rate of 27.4%. The results of this study improved corn stalk utilization, reduced hydrolysis costs, and generated high ethanol yields.

Optimization of Fermentation Conditions for the Production of Angiotensin-Converting Enzyme (ACE) Inhibitory Peptides from Cow Milk by Lactobacillus bulgaricus LB6

Abstract The purpose of this research was to screen out the optimal -producing peptide conditions for cow milk fermented by Lactobacillus bulgaricus LB6. The effects of temperature, inoculation size, time and skim milk concentration on the ACE inhibition rate of fermented milk were investigated by single factor experiment, and the optimal fermentation conditions were determined by orthogonal experiment. The conditions of the single factor experiment were: Temperatures were 37° C, 39° C, 42° C, 44° C and 46° C. The inoculation amount was 1%, 3%, 5%, 7% and 9%, the time was 8h and 10h. At 12h, 14h and 16h, the concentration of skim milk was 8%, 10%, 12%, 14% and 16%, respectively. The results showed that the optimal fermentation conditions for ACE inhibitory peptide produced by Lactobacillus bulgaricus LB6 were 4% inoculation, 13h in time, 42°C in temperature and 13% in skim milk. Under this condition, the ACE inhibition rate reached 76.50% and the OD value was 0.330. The titration acidity was 116.4°T, the pH was 4.62, and the sensory evaluation was 75 scores.

Effects of inoculation amount and application method on the biodrying performance of municipal solid waste and the odor emissions produced

The effects of inoculation amount and application method on the biodrying of municipal solid waste (MSW) was investigated in this study. Results showed that a low level (5%) of inoculation with mature compost significantly improved the biodrying index (4.96), while adding greater amounts decreased the biodrying performance by increasing the volatile solid degradation rate. Covering the pile with inoculation material resulted in the highest water removal (72.7%) and greatest water content reduction (from 60.2% to 17.7%). Meanwhile, first covering and then incorporating the inoculation material into the biodrying pile did not improve biodrying performance. Clearly, addition of varying amounts of inoculation material via different application methods enhanced cellulose degradation rates by 2.3–14.2%. Using 10% inoculation material reduced the NH3 emissions by 39.1–54.3% regardless of inoculation method, inoculation amount had a greater effect on NH3 emissions than that of inoculation method. The covering inoculation material could reduce 65.08% H2S emission, the inoculation method had a greater effect on H2S emissions than that of inoculation amount. Given the comprehensive considerations of emission reduction and biodrying performance, a covering of 10% inoculating material is a suitable approach to improve biodrying performance and mitigate odorous gases emissions.

Microbial synthesis of anti-tumor agent oxysophoridine through one step by filamentous fungus

Sophoridine and oxysophoridine are alkaloids extracted from Chinese traditional medicine with significant antitumor activities. Computer-aided design and preliminary structure-activity relationship studies showed that the biological activity of sophoridine can be improved after oxidation (oxysophoridine) while its toxicity significantly decreased. A new method to prepare oxysophoridine from natural product Sophoridine by biotransformation was established for the first time except for traditional extraction from plants and chemical synthesis. Positive biocatalytic reaction was detected by TLC. Structure of conversion product was elucidated based on NMR spectroscopy. Optimizations of reactions including substrate concentration, pH, conversion time and inoculation quantity were complemented which analyzed by LC-MS. Results showed that filamentous fungus Xylariales. sp F005 (CCTCC M2014660) has the capacity of synthetizing oxysophoridine from sophoridine in the selected 37 strains. The yield of oxysophoridine reached highest at conditions pH 6.0, the third day of conversion time, 5.0 mg substrate and 5% inoculums respectively. The method for preparing oxysophoridine catalyzed by enzymes with green and sustainable synthetic processes was developed.

Yellow pigment of Metarhizium anisopliae and its application to the dyeing of fabrics

Microbial dyes have received substantial attention because of their natural environmental protection, simple access, and reduced regional and seasonal restriction. In this work, a microbial dye, the yellow pigment produced by Metarhizium anisopliae, was first studied then applied. The strain produced by the culture was identified, and the conditions for producing yellow pigment were optimised. Further, the stability of M. anisopliae yellow pigment was examined, and the pigment was applied to the dyeing of silk and wool fabrics. The results showed that the homology of the strain with M. anisopliae was 99.98%. In liquid fermentation culture, the optimal carbon source was glucose, and the dosage was 30 g/l. The maximum pigment yield can be obtained by culturing with 4% v/v of inoculation quantity at pH 7 and 30 °C. In addition, the effects of pH, temperature and metal ions on the yellow pigment of M. anisopliae were significant. The optimum dyeing process conditions were dyeing temperatures of 80 °C for silk and 90 °C for wool, with a dyeing time of 60 min. This research developed a novel microbial dye and studied its application for the dyeing of protein fibres.