Aspergillus humicola, one of the major cellulase-producing fungi, was used in this study for carboxymethylcellulase (CMCase) production using Winstead's basal broth supplanted with cellobiose octaacetate (COA), a synthetic carbon source. Under all conditions, the enzyme biosynthesis was remarkably increased when the inducer COA was added to the production medium containing carboxymethylcellulose (CMC). Maximum enzyme production (1.62 U/ml) was achieved in COA-containing at 37°C. The enzyme production was highest at initial pH 5.5 and after 7 days incubation. The enzyme exhibited maximum activity at 40°C with a reaction pH 5.5. CMCase activity was inhibited by its own substrate CMC at concentration higher than 1.0%. The study clearly demonstrated that COA is a good inducer for extracellular CMCase production by the fungus. Keywords: Aspergillus humicola, Carboxymethylcellulase (CMCase), Carboxymethylcellulose (CMC), Cellobiose octaacetate (COA)DOI: http://dx.doi.org/10.3329/bjm.v23i2.889 Bangladesh J Microbiol, Volume 23, Number 2, December 2006, pp 174-176
Context: Waste water containing Chromium (Cr 6+ ) is by far the most important environmental challenge being faced.
Objectives:The present study was planned on the isolation and characterization of chromate resistant and reducing bacterial strains in order to use them for detoxification of chromate.
Materials and Methods:Water samples were collected to isolate microorganisms from tannery effluent of Baluchara, Chittagong and inoculated into Luria-Bertani medium with added Cr 6+ as K2Cr2O7. The organisms have been identified and studied for Cr 6+ reduction-ability in growth dependent manner.Results: A total of 35 isolates have been selected as potential organism belonging to the species of Moraxella (14.3%), Bacillus (11.43%), Streptococcus (25.72%), Staphylococcus (5.7%), Salmonella (12.3%), E. coli (13.3%), Enterobacter (11.3%), Hafnia alvei (2.45%) and Alcaligenes (3.5%). The selected isolates were able to tolerate at least 500 mg/l of Cr 6+ . The total Cr 6+ concentration of the effluent sample analysed was found to be about 23.73 mg/l as determined by Atomic Absorption Spectrophotometry. Two of the isolates reduced 38% and 32% of Cr 6+ added to the medium. Another 7 isolates showed Cr 6+ reducing capability ranging from 18 to 22%.
Conclusion:As the isolates have turned out to successfully reduce Cr 6+ in this study, these can be used for the development of bioremediation process.
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