The objective of this study was to isolate and identify a yeast strain from the kombucha beverage and evaluate its potential as a novel starter in beverage fermentation in vitro.Starmerella davenportii Do18 was charac...The objective of this study was to isolate and identify a yeast strain from the kombucha beverage and evaluate its potential as a novel starter in beverage fermentation in vitro.Starmerella davenportii Do18 was characterized for its cholesterol reduction;growth at different conditions such as temperatures(25,30,37 and 42◦C),low pH(1.2,1.5,2.03.0,and 7.0),bile salts(0%,0.25%,0.5%,1%and 2%)high-sucrose stress(2%,10%,20%,40%and 60%);and in-vitro survival in gastric and intestinal environments.Results showed that the yeast strain has a cholesterol-lowering capacity of 45%±2%,grew at temperature of 37◦C and is resistant to pH 1.5,2%bile and 40%sucrose solution,could survive in simulated gastric and intestinal environments.The physicochemical characteristics of the fermented beverages were also evaluated,which indicated that the yeast has pH reduction capacity and can produce organic acids and volatile compound such as 2-phenylethanol.Furthermore,the fermented beverage also has high total phenolics and flavonoids content and showed great antioxidant and antimicrobial activities.Therefore,the findings of this research provide strong evidence that S.davenportii Do18 has good fermentation properties,can be a potential starter in food and beverage fermentation.展开更多
The feasibility of utilizing soybean-processing residues such as soybean meal and hulls as substrates for chitosan production by the fungus Mucor rouxii ATCC 24905 via solid-state fermentation (SSF) was investigated. ...The feasibility of utilizing soybean-processing residues such as soybean meal and hulls as substrates for chitosan production by the fungus Mucor rouxii ATCC 24905 via solid-state fermentation (SSF) was investigated. The effects of the type of soybean-based substrate, length of cultivation period, substrate moisture content, substrate pH, incubation temperature and extraction conditions on chitosan yield were determined. The results showed that a maximum fungal chitosan yield of up to 3.44% by dry substrate weight (34.4 g/kg) could be achieved using a pure soybean meal substrate with an initial moisture content of 50% (w/w) and pH of 5 - 6 incubated for six days at 25°C. A more severe heat treatment (autoclaving vs. refluxing) resulted in higher chitosan extraction yields regardless of the strength of extraction reagents. Fourier transform infrared (FTIR) analysis of the fungal chitosan revealed its degree of deacetylation (DDA) to be between 55% and 60%.展开更多
Cassava peels are rich in lignocellulolytic materials which are not readily amenable to enzymatic hydrolysis;hence, there is a need for a suitable pretreatment method that will support enzymatic hydrolysis. This study...Cassava peels are rich in lignocellulolytic materials which are not readily amenable to enzymatic hydrolysis;hence, there is a need for a suitable pretreatment method that will support enzymatic hydrolysis. This study was designed to investigate lignocellulolytic organisms that would effectively support the bioconversion of organosolv pretreated cassava peels to fermentable sugars. Decaying cassava peels were collected into sterile bottles and microorganisms isolated, characterized and screened for lignocellulolytic enzymes production. Optimum temperature, pH and nutrient sources for enzyme production were determined. Organosolv pretreatment was carried out using methanol with varied concentration of catalyst (0.01 - 3 M), reaction time (15 - 60 min) and substrate size. Crude enzymes (cellulase and xylanase) from the isolates were added to the pretreated peels and bioconversion was monitored by measuring the concentration of reducing sugar and calculating the percentage peel hydrolysis. The fermentable sugars produced were quantified using gas chromatography. Pseudomonas fluorescens and Aspergillus terreus were isolated. P. fluorescens produces 2.8 u/mL of crude enzymes optimally at 50°C and pH 8 while A. terreus produces 3.4 u/mL optimally at 40°C, pH 6. Both isolates utilizes CarboxyMethylCellulose (CMC) and yeast extract as their best carbon and nitrogen sources. Highest percentage of peel hydrolysis was 67% for P. fluorescens at 0.01 M and 0.05 M for A. terreus (94%). Highest concentration of fermentable sugar was produced by A. terreus crude enzyme (331.79 mg/L glucose, 45.3 mg/L rhamnose and 46.52 mg/L xylose). P. fluorescens and A. terreus effectively supported the bioconversion of organosolv pretreated cassava peels to fermentable sugars.展开更多
Nanocellulose has various outstanding properties and great potential for replacing petrochemical products.The utilization of lignocellulose to produce nanocellulose is of great significance to the sustainable developm...Nanocellulose has various outstanding properties and great potential for replacing petrochemical products.The utilization of lignocellulose to produce nanocellulose is of great significance to the sustainable development of the economy and society.However,the direct extraction of nanocellulose from lignocellulose by chemical method is challenged by toxic chemicals utilization,energy and time consumption,and waste water generation.Therefore,this paper addressed the conversion of lignocellulosic biomass into bacterial nanocellulose(BNC)by the biological method.Moreover,this article highlights the recent advances in potentials and challenges of lignocellulosic biomass for BNC production through the bioconversion process,including biomass pretreatment,enzymatic hydrolysis,glucose and xylose fermentation,GA accumulation,and inhibitor tolerant.The development in metabolic and evolutionary engineering to enhance the production capacity of BNC-producing strain is also discussed.It is expected to provide guidance on the effective bioproduction of nanocellulose from lignocellulosic biomass.展开更多
基金This work was supported by the Jiangsu Agricultural Industry Technology System[No.JATS-2018-296]and the National Natural Science Foundation of China[Grant No.31501460].
文摘The objective of this study was to isolate and identify a yeast strain from the kombucha beverage and evaluate its potential as a novel starter in beverage fermentation in vitro.Starmerella davenportii Do18 was characterized for its cholesterol reduction;growth at different conditions such as temperatures(25,30,37 and 42◦C),low pH(1.2,1.5,2.03.0,and 7.0),bile salts(0%,0.25%,0.5%,1%and 2%)high-sucrose stress(2%,10%,20%,40%and 60%);and in-vitro survival in gastric and intestinal environments.Results showed that the yeast strain has a cholesterol-lowering capacity of 45%±2%,grew at temperature of 37◦C and is resistant to pH 1.5,2%bile and 40%sucrose solution,could survive in simulated gastric and intestinal environments.The physicochemical characteristics of the fermented beverages were also evaluated,which indicated that the yeast has pH reduction capacity and can produce organic acids and volatile compound such as 2-phenylethanol.Furthermore,the fermented beverage also has high total phenolics and flavonoids content and showed great antioxidant and antimicrobial activities.Therefore,the findings of this research provide strong evidence that S.davenportii Do18 has good fermentation properties,can be a potential starter in food and beverage fermentation.
文摘The feasibility of utilizing soybean-processing residues such as soybean meal and hulls as substrates for chitosan production by the fungus Mucor rouxii ATCC 24905 via solid-state fermentation (SSF) was investigated. The effects of the type of soybean-based substrate, length of cultivation period, substrate moisture content, substrate pH, incubation temperature and extraction conditions on chitosan yield were determined. The results showed that a maximum fungal chitosan yield of up to 3.44% by dry substrate weight (34.4 g/kg) could be achieved using a pure soybean meal substrate with an initial moisture content of 50% (w/w) and pH of 5 - 6 incubated for six days at 25°C. A more severe heat treatment (autoclaving vs. refluxing) resulted in higher chitosan extraction yields regardless of the strength of extraction reagents. Fourier transform infrared (FTIR) analysis of the fungal chitosan revealed its degree of deacetylation (DDA) to be between 55% and 60%.
文摘Cassava peels are rich in lignocellulolytic materials which are not readily amenable to enzymatic hydrolysis;hence, there is a need for a suitable pretreatment method that will support enzymatic hydrolysis. This study was designed to investigate lignocellulolytic organisms that would effectively support the bioconversion of organosolv pretreated cassava peels to fermentable sugars. Decaying cassava peels were collected into sterile bottles and microorganisms isolated, characterized and screened for lignocellulolytic enzymes production. Optimum temperature, pH and nutrient sources for enzyme production were determined. Organosolv pretreatment was carried out using methanol with varied concentration of catalyst (0.01 - 3 M), reaction time (15 - 60 min) and substrate size. Crude enzymes (cellulase and xylanase) from the isolates were added to the pretreated peels and bioconversion was monitored by measuring the concentration of reducing sugar and calculating the percentage peel hydrolysis. The fermentable sugars produced were quantified using gas chromatography. Pseudomonas fluorescens and Aspergillus terreus were isolated. P. fluorescens produces 2.8 u/mL of crude enzymes optimally at 50°C and pH 8 while A. terreus produces 3.4 u/mL optimally at 40°C, pH 6. Both isolates utilizes CarboxyMethylCellulose (CMC) and yeast extract as their best carbon and nitrogen sources. Highest percentage of peel hydrolysis was 67% for P. fluorescens at 0.01 M and 0.05 M for A. terreus (94%). Highest concentration of fermentable sugar was produced by A. terreus crude enzyme (331.79 mg/L glucose, 45.3 mg/L rhamnose and 46.52 mg/L xylose). P. fluorescens and A. terreus effectively supported the bioconversion of organosolv pretreated cassava peels to fermentable sugars.
基金supported by the National Natural Science Foundation of China, Grant Nos. 22108205 and 21978219the Scientific Research Program of Tianjin Education Commission, Grant No. 2019KJ237。
文摘Nanocellulose has various outstanding properties and great potential for replacing petrochemical products.The utilization of lignocellulose to produce nanocellulose is of great significance to the sustainable development of the economy and society.However,the direct extraction of nanocellulose from lignocellulose by chemical method is challenged by toxic chemicals utilization,energy and time consumption,and waste water generation.Therefore,this paper addressed the conversion of lignocellulosic biomass into bacterial nanocellulose(BNC)by the biological method.Moreover,this article highlights the recent advances in potentials and challenges of lignocellulosic biomass for BNC production through the bioconversion process,including biomass pretreatment,enzymatic hydrolysis,glucose and xylose fermentation,GA accumulation,and inhibitor tolerant.The development in metabolic and evolutionary engineering to enhance the production capacity of BNC-producing strain is also discussed.It is expected to provide guidance on the effective bioproduction of nanocellulose from lignocellulosic biomass.
