Isolation, identification and screening of potential cellulase-free xylanase producing fungi

In order to isolate cellulase-free xylanase-producing fungi, screening and isolation of fungi was done using decaying wood, agricultural wastes and other lignocellulosic wastes as microbial source. Thirty (30) fungal species were selected for further analysis based upon clearing zones formation on xylan enriched agar plates. Submerged fermentation was done with 30 fungal isolates to identify strain that could produce highest amount of cellulase-free xylanase at a pH of 5.5 and at 28 ± 2°C temperature. Under screening conditions, 90% of the strains produced xylanase (6.6 to 495 U/ml) and negligible amount of cellulase ( 0.6 U/ml) with growth. Growth was determined in terms of mycelial dry weight which ranged between 0.6 to 2.34 mg/ml. The amount of soluble protein was also determined which ranged between 102 to 300 g/ml. The pH change after incubation was in between 5.0 to 8.0. Strain specific variability in xylanase production was confirmed in Aspergillus sp. and Penicillium sp. In addition, this study shows here that Rhizopus sp. can also produce xylanase under given conditions.Key words: Cellulase-free xylanase, xylan, xylanase, submerged fermentation, malt extract agar

Strain improvement in dye decolourising mutants of Mucor mucedo by protoplast fusion

The amounts of protoplasts obtained in the developed mutants of M. mucedo MMM1 (U.V. irradiated mutant) and MMM2 (ethyl methyl sulfonate treated mutant) which are very effective decolourisers were 5.23 x 106 and 5.65 x 106 protoplasts/ml respectively. Among the 385 colonies isolated after protoplast fusion only 3 possessed clamp connections and chosen as fusants (MMFu1, MMFu2 and MMFu3). Of the 3 fusants, MMFu3 showed maximum growth rate on potato dextrose agar plates incubated at roomtemperature. The fusant MMFu3 showed very good increase in the production of three enzymes protease (1.90 U/ml), peroxidase (1100 U/ml) and laccase (200 U/ml) when compared to the two parentstrains proving that the higher enzymatic secretions are responsible for the decolourisation activity. In protease isozyme analysis, fusants showed bands common to either of the parental strains or to both. Further non parental new bands were observed in the protease isozyme patterns of MMFu3. This fact indicated that the isolates were fusants between MMM1 and MMM2. The fusant MMFu3 showed the maximum decolourisation of crystal violet up to 95% and malachite green up to 84% after 10 days ofincubation. The results clearly indicated that the protoplast fusants showed improvement in the decolourisation efficiency in both the cases of crystal violet and malachite green

Antimicrobial activity of the fruit extracts of Coccinia indica

The bioactive compounds of fruits of Coccinia indica were investigated for antibacterial activity against some pathogenic bacteria. The aqueous extracts did not show much significant activity, while the organic extracts (petroleum ether and methanol) showed the highest activity against the test bacteria.The activity was more pronounced on gram-positive organisms with Staphylococcus aureus being more susceptible and Salmonella paratyphi A being more resistant. Phytochemical analysis showed that the extracts contain alkaloids, tannins, saponins, flavonoids, glycosides and phenols

Antibacterial studies and phytochemical constituents of South Indian Phyllanthus species

Antibacterial activity and phytochemical tests of the methanol extracts of six Phyllanthus species were evaluated. In agar well diffusion assay the diameter of inhibition zones ranged from 3 - 22 mm. Phyllanthus amarus showed maximum activity of 22 mm. The minimum inhibition concentration (MIC)and minimum bactericidal concentration (MBC) observed for Bacillus stearothermophilus, Staphylococcus aureus, Bacillus subtilis, Micrococcus leuteus, Salmonella typhi, Enterobacter aerogens, Proteus mirabilis, and Proteus vulgaris were 30 - 205 ìg/ml and 40 - 230 ìg/ml, respectively.P. amarus, P. hookeri and P. maderaspatensis showed the lowest MIC (30 ìg/ml) as well as MBC (40 ìg/ml) and thus an effective inhibitor of the tested bacteria. Lignans, triterpenoids and phenols were detected in all the 6 tested plants