Effect of medium composition and ultrasonication on xylanase production by Trichoderma harzianum MTCC 4358 on novel substrate

Sunflower sludge was used as the sole carbon source for xylanase production, an important industrial enzyme used in pulp and paper industry, by the fungi Trichoderma harzianum MTCC 4358. Sunflower sludge was subjected to alkaline pretreatment which showed higher enzyme activity than the substrate used without pretreatment. The effect and significance of the medium components were studied using the Plackett-Burman design. The experimental xylanase activity was subjected to statistical analysis using MINITAB 15 software. It was found that peptone, urea, CaCl2.2H2O, Tween 80, (NH4)2.SO4, MgSO4.7H2O and MnSO4 significantly influenced xylanase production (8.63 U/g of dry substrate). The enzyme showed maximum activity at pH 5 (8.75 U/g of dry substrate), 45°C (8.66 U/g of dry substrate) and 80% initial moisture content (8.84 U/g of dry substrate) and a period of 7 days incubation (8.57 U/g of dry substrate) was necessary for maximum enzyme production. Under these optimized physical conditions and in optimized medium T. harzianum MTCC 4358 was inoculated and subjected to ultrasonication for every 12 h (for a period of 8 days), which resulted in higher enzymatic activity of 9.27 U/g of dry substrate.Keywords: Xylanase, Trichoderma harzianum, ultrasonication, sunflower sludge, Plackett-Burman desig

The Potential of the Photoautotroph Synechocystis for Metal Bioremediation

The photoautotrophic cyanobacterium Synechocystis PCC6803 has received much attention as a model photosynthetic cell factory for the production of a range of important biotech products. The biomass remaining from this activity may then have further utility in processes such as metal bioremediation. In addition Synechocystis being an inhabitant of many natural aquatic environments is seen as an environmentally friendly alternative to using chemical precipitation methodologies for metal remediation. Synechocystis produces a range of extracellular polysaccharide substances (EPS) that can undergo modification as a function of culture age and growth nutrients which have been implicated in metal biosorption. Many studies have demonstrated that high levels of charged groups present in EPS are important in forming polymeric matrices with metallic ions allowing their biosorption. Genetic studies has revealed genes involved in such metal binding indicating that EPS can be modified for potential enhancement of binding or modification of the types of metals bound. The utility of metal binding to live and dead biomass of Synechocystis has been demonstrated for a range of metals including Cr(VI), Cd(II), Cu(II), Pb(II), Sb, Ni(II), Mn(II), Mn(IV), As(III), As(V), Cs and Hg. The potential of using Synechocystis as a biosorption platform is discussed

Antioxidant and antimicrobial efficacies of Amaranthus polygonoides and its impact on L-asparaginase production

Traditional medicinal herbs play a vital role in primary healthcare throughout the world. The current investigation represents the analysis of antioxidant, antimicrobial activities of Amaranthus polygonoides and its application in L-asparaginase (anti-leukemic enzyme) production. The plant leaves were dried and extracted with distilled water to yield their crude extracts. Further, this extract was subjected to screening of antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method and nitric oxide scavenging activity. The extract was found to have the highest DPPH free radical scavenging activity (84%) and nitric oxide scavenging activity (71.8%). Moreover, the extract was proved to be active against Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Klebseilla pneumonia, Aspergillus niger and Aspergillus fumigatus through antimicrobial activity test. After the initial assessment, the extract was screened for the production of L-asparaginase by Streptomyces venezuelae using rapid plate assay and confirmed the enzyme production by zone formation. The effect of concentration of A. polygonoides leaves extract on specific growth rate and specific L-asparaginase production rate was evaluated thorough Monod kinetics and the maximum specific growth rate, μm and maximum L-asparaginase production rate, Pm were found to be 0.8683 and 0.7902 h-1, respectively.Keywords: Amaranthus polygonoides, antioxidant, L-asparaginase, production kinetic

Ultrasonic intensification as a tool for enhanced microbial biofuel yields

peer-reviewedUltrasonication has recently received attention as a novel bioprocessing tool for process intensification in many areas of downstream processing. Ultrasonic intensification (periodic ultrasonic treatment during the fermentation process) can result in a more effective homogenization of biomass and faster energy and mass transfer to biomass over short time periods which can result in enhanced microbial growth. Ultrasonic intensification can allow the rapid selective extraction of specific biomass components and can enhance product yields which can be of economic benefit. This review focuses on the role of ultrasonication in the extraction and yield enhancement of compounds from various microbial sources, specifically algal and cyanobacterial biomass with a focus on the production of biofuels. The operating principles associated with the process of ultrasonication and the influence of various operating conditions including ultrasonic frequency, power intensity, ultrasonic duration, reactor designs and kinetics applied for ultrasonic intensification are also described

Chapter The Potential of the Photoautotroph Synechocystis for Metal Bioremediation

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