An endoglucanase (1, 4-b-D glucan glucanohydrolase, EC 3.2.1.4) which was catalytically more active and exhibited higher affinity towards barley b-glucan, xyloglucan and lichenin as compared to carboxymethylcellulose (CMC) was purified from Aspergillus terreus strain AN 1 following ion-exchange and hydrophobic interaction chromatography and gel filtration. The purified enzyme (40-fold) that apparently lacked a cellulose-binding domain showed a specific activity of 60 lmol mg -1 protein -1 against CMC. The purified enzyme had a molecular weight of 78 and 80 KDa as indicated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and gel filtration, respectively, and a pI of 3.5. The enzyme was optimally active at temperature 60°C and pH 4.0, and was stable over a broad range of pH (3.0-5.0) at 50°C. The endoglucanase activity was positively modulated in the presence of Cu 2? , Mg 2? , Ca 2? , Na ? , DTT and mercaptoethanol. Endoglucanase exhibited maximal turn over number (K cat ) and catalytic efficiency (K cat/km ) of 19.11 9 10 5 min -1 and 29.7 9 10 5 mM -1 min -1 against barley b-glucan as substrate, respectively. Hydrolysis of CMC and barley b-glucan liberated cellobiose, cellotriose, cellotetraose and detectable amount of glucose. The hydrolysis of xyloglucan, however, apparently yielded positional isomers of cellobiose, cellotriose and cellotetraose as well as larger oligosaccharides.
This study reports differential expression of endoglucanase (EG) and beta-glucosidase (betaG) isoforms of Aspergillus terreus. Expression of multiple isoforms was observed, in presence of different carbon sources and culture conditions, by activity staining of poly acrylamide gel electrophoresis gels. Maximal expression of four EG isoforms was observed in presence of rice straw (28 U/g DW substrate) and corn cobs (1.147 U/ml) under solid substrate and shake flask culture, respectively. Furthermore, the sequential induction of EG isoforms was found to be associated with the presence of distinct metabolites (monosaccharides/oligosaccharides) i.e., xylose (X), G(1), G(3) and G(4) as well as putative positional isomers (G(1)/G(2), G(2)/G(3)) in the culture extracts sampled at different time intervals, indicating specific role of these metabolites in the sequential expression of multiple EGs. Addition of fructose and cellobiose to corn cobs containing medium during shake flask culture resulted in up-regulation of EG activity, whereas addition of mannitol, ethanol and glycerol selectively repressed the expression of three EG isoforms (Ia, Ic and Id). The observed regulation profile of betaG isoforms was distinct when compared to EG isoforms, and addition of glucose, fructose, sucrose, cellobiose, mannitol and glycerol resulted in down-regulation of one or more of the four betaG isoforms.
A thermotolerant Aspergillus fumigatus strain isolated from composting pile of mixed industrial waste was found to produce a spectrum of cellulase and hemicellulases when cultured on rice straw solidified substrate. The two-dimensional electrophoresis (2DE) resolved the secretome into 57 distinct protein spots. The zymograms developed against 2DE gels identified the presence of three β-glucosidases and five CBHI/EGI isoforms in the secretome. The peptide mass fingerprinting of 17 protein spots by liquid chromatography mass spectrometry characterized the secretome into different glycosyl hydrolase families. The enzyme cocktail produced by A. fumigatus was capable of efficient hydrolysis of alkali pretreated rice straw (at 7% and 10% w/v) resulting in 95% and 91% saccharification, respectively.
Endophytic fungi are an important component that colonizes in healthy tissues of living plants and can be readily isolated from any microbial or plant growth medium. They act as reservoirs of novel bioactive secondary metabolites, such as alkaloids, phenolic acids, quinones, steroids, saponins, tannins, and terpenoids that serve as a potential candidate for antimicrobial, anti-insect, anticancer and many more properties. Their huge diversity and particular habituation, they can provide a good area for research in the field of making new medicines and novel drug-like molecules. Because of the impact of endophytes on host plant by enhancing their growth or increasing their fitness, also making them tolerant to abiotic and biotic stresses and holding the secondary metabolites, endophytes are gaining attention as a subject for research. This review aims to comprehend the contribution and uses of endophytes and relationships between endophytic fungi and their host medicinal plants.
This study aimed to investigate total phenolic content and antibacterial activities of different extracts recovered from date palm fruit and leaves using various solvents, including methanol, ethanol, and water. The results showed that the highest phenolic content was found in leaf methanol extract, followed by leaf ethanol extract, and then followed by seed methanol extract (74.4, 67.3, and 64.7 mg/g, respectively). Whereas the date methanol extract had the lowest phenolic content (5 mg/g). The study was also scrutinized to find the antibacterial inhibitory property in the leaves and fruits of date palm against four bacterial species (Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa) using the well-diffusion method and minimum inhibitory concentration (MIC). Date leaves' extracts showed inhibitory effect on the growth of S. aureus and B. subtilis and resistance to P. aeruginosa and E. coli. MIC of methanol and ethanol (70%) leaves' extract was 100 and 250 mg/ml for S. aureus and B. subtilis, respectively; however, all the bacteria have resistance to date fruits' extracts.
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