Xylanase is an important enzyme with potential application in the degradation of xylan component in the lignocellulosic biomass. There are very few reports on the production of cellulase free xylanases especially by y...Xylanase is an important enzyme with potential application in the degradation of xylan component in the lignocellulosic biomass. There are very few reports on the production of cellulase free xylanases especially by yeast strains which have great potential in paper and pulp industry in removing the hemicellulose from the treated or untreated pulp. In this study, P. hubeiensis NCIM 3574 isolated in our laboratory produced significant levels of extracellular cellulase free xylanase (2480 IU/g DSS) in solid state fermentation (SSF) using wheat bran and xylan. It also produced high levels of β-xylosidase (198 IU/g DSS) when grown in SSF using ground nut oil cake and xylan. These highest activities were obtained when fermented Koji was extracted with 1% NaCl supplemented with 0.5% of Triton X-100. These are the highest activities reported so far from yeast strains in the available literature. The crude xylanase preparation of P. hubeiensis produced xylooligosaccharides (XOS) without xylose proving its potential for XOS production with no further requirement of downstream processing. The XOS as prebiotic show beneficial effect on gut microflora such as Lactobacilli and Bifidobacteria which suppress the activity of pathogenic organisms. This xylanase also has a potential application as a bio-bleaching agent in paper and pulp industry.展开更多
Production of high titers of an alkaline, extracellular and thermo-tolerant pectinase by a newly isolated yeast Pseudozyma sp. SPJ was carried out under solid state fermentation. Citrus peel, the inexpensive agro-indu...Production of high titers of an alkaline, extracellular and thermo-tolerant pectinase by a newly isolated yeast Pseudozyma sp. SPJ was carried out under solid state fermentation. Citrus peel, the inexpensive agro-industrial residue used as substrate, was experienced to be unsurpassed. Response surface methodology was conducted to optimize the culture conditions for Pseudozyma sp. SPJ for hyper production of pectinase. Plackett Burman design was applied to identify the most effective culture variables. Out of nine variables studied, incubation time, moisture content and ammonium sulfate were detected as most important. A full factorial Central Composite Design was used to optimize the levels of these variables, which resulted in 17-fold increase （71.19 IU/g to 1215.66 IU/g dry substrate） in the enzyme yield. The results of analysis of variance and multiple regression analysis implies that the effect of incubation time （p 〈 0.000） and moisture content （p 〈 0.018） is more than ammonium sulfate. And also the interaction of moisture content with ammonium sulfate （p 〈 0.002） is more significant.展开更多
Green coffee seeds from Colombia, Guatemala, India, Kenya, Papua New Guinea, Puerto Rico and Vietnam were sampled for the presence of fungal endophytes. Stions of surface sterilized seeds were plated on yeast malt aga...Green coffee seeds from Colombia, Guatemala, India, Kenya, Papua New Guinea, Puerto Rico and Vietnam were sampled for the presence of fungal endophytes. Stions of surface sterilized seeds were plated on yeast malt agar, and fungal growth was isolated for subsequent DNA extraction and sequencing. Several fungal genera were isolated, including Acremonium, Aspergillus, Eurotium, Fusarium, Gibberella, Penicillium, Pseudozyma and an undescribed clavicipitaceous species. The biological activities that these fungi might be playing in coffee seeds remain unknown, but in other plants some of the genera isolated have been reported to protect against plant pathogens.展开更多
文摘Xylanase is an important enzyme with potential application in the degradation of xylan component in the lignocellulosic biomass. There are very few reports on the production of cellulase free xylanases especially by yeast strains which have great potential in paper and pulp industry in removing the hemicellulose from the treated or untreated pulp. In this study, P. hubeiensis NCIM 3574 isolated in our laboratory produced significant levels of extracellular cellulase free xylanase (2480 IU/g DSS) in solid state fermentation (SSF) using wheat bran and xylan. It also produced high levels of β-xylosidase (198 IU/g DSS) when grown in SSF using ground nut oil cake and xylan. These highest activities were obtained when fermented Koji was extracted with 1% NaCl supplemented with 0.5% of Triton X-100. These are the highest activities reported so far from yeast strains in the available literature. The crude xylanase preparation of P. hubeiensis produced xylooligosaccharides (XOS) without xylose proving its potential for XOS production with no further requirement of downstream processing. The XOS as prebiotic show beneficial effect on gut microflora such as Lactobacilli and Bifidobacteria which suppress the activity of pathogenic organisms. This xylanase also has a potential application as a bio-bleaching agent in paper and pulp industry.
文摘Production of high titers of an alkaline, extracellular and thermo-tolerant pectinase by a newly isolated yeast Pseudozyma sp. SPJ was carried out under solid state fermentation. Citrus peel, the inexpensive agro-industrial residue used as substrate, was experienced to be unsurpassed. Response surface methodology was conducted to optimize the culture conditions for Pseudozyma sp. SPJ for hyper production of pectinase. Plackett Burman design was applied to identify the most effective culture variables. Out of nine variables studied, incubation time, moisture content and ammonium sulfate were detected as most important. A full factorial Central Composite Design was used to optimize the levels of these variables, which resulted in 17-fold increase （71.19 IU/g to 1215.66 IU/g dry substrate） in the enzyme yield. The results of analysis of variance and multiple regression analysis implies that the effect of incubation time （p 〈 0.000） and moisture content （p 〈 0.018） is more than ammonium sulfate. And also the interaction of moisture content with ammonium sulfate （p 〈 0.002） is more significant.
文摘Green coffee seeds from Colombia, Guatemala, India, Kenya, Papua New Guinea, Puerto Rico and Vietnam were sampled for the presence of fungal endophytes. Stions of surface sterilized seeds were plated on yeast malt agar, and fungal growth was isolated for subsequent DNA extraction and sequencing. Several fungal genera were isolated, including Acremonium, Aspergillus, Eurotium, Fusarium, Gibberella, Penicillium, Pseudozyma and an undescribed clavicipitaceous species. The biological activities that these fungi might be playing in coffee seeds remain unknown, but in other plants some of the genera isolated have been reported to protect against plant pathogens.
