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
Objective:To isolate,evaluate and characterize potential antibiotic producing actinomycetes from water and sediments of Lake Tana,Ethiopia.Methods:A total of 31 strains of actinomycetes were isolated and tested agains...Objective:To isolate,evaluate and characterize potential antibiotic producing actinomycetes from water and sediments of Lake Tana,Ethiopia.Methods:A total of 31 strains of actinomycetes were isolated and tested against Gram positive and Gram negative bacterial strains by primary screening.In the primary screening.11 promising isolates were identified and subjected to solid state and submerged state fermentation methods to produce crude extracts.The fermented biomass was extracted by organic solvent extraction method and tested against bacterial strains by disc and agar well diffusion methods.The isolates were characterized by using morphological,physiological and biochemical methods.Results:The result obtained from agar well diffusion method was belter than disc diffusion method.The crude extract showed higher inhibition zone against Gram positive bacteria than Cram negative bacteria.One-way analysis of variance confirmed most of the crude extracts were statistically significant at 95%confidence interval.The minimum inhibitor)concentration and minimum bactericidal concentration of crude extracts were 1.65 mg/mL and 3.30 mg/mL against Staphylococcus aureus,and 1.84 mg/mL and 3.80 mg/mL against Escherichia coli respectively.The growth of aerial and substrate mycelium varied in different culture media used.Most of the isolates were able to hydrolysis starch and urea:able to survive at 5%concentration of sodium chloride:optimum temperature for their growth was 30°C.Conclusions:The results of the present study revealed that freshwater actinomycetes of Luke Tana appear to have immense potential as a source ol antibacterial compounds.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.
基金Supported by University of Gondar under Teaching and Learning Program(UoG/Budget code:6417)
文摘Objective:To isolate,evaluate and characterize potential antibiotic producing actinomycetes from water and sediments of Lake Tana,Ethiopia.Methods:A total of 31 strains of actinomycetes were isolated and tested against Gram positive and Gram negative bacterial strains by primary screening.In the primary screening.11 promising isolates were identified and subjected to solid state and submerged state fermentation methods to produce crude extracts.The fermented biomass was extracted by organic solvent extraction method and tested against bacterial strains by disc and agar well diffusion methods.The isolates were characterized by using morphological,physiological and biochemical methods.Results:The result obtained from agar well diffusion method was belter than disc diffusion method.The crude extract showed higher inhibition zone against Gram positive bacteria than Cram negative bacteria.One-way analysis of variance confirmed most of the crude extracts were statistically significant at 95%confidence interval.The minimum inhibitor)concentration and minimum bactericidal concentration of crude extracts were 1.65 mg/mL and 3.30 mg/mL against Staphylococcus aureus,and 1.84 mg/mL and 3.80 mg/mL against Escherichia coli respectively.The growth of aerial and substrate mycelium varied in different culture media used.Most of the isolates were able to hydrolysis starch and urea:able to survive at 5%concentration of sodium chloride:optimum temperature for their growth was 30°C.Conclusions:The results of the present study revealed that freshwater actinomycetes of Luke Tana appear to have immense potential as a source ol antibacterial compounds.
