No abstract

Exoglucanase and endoglucanase (glucanases) enzymes of S. albaduncus were found to be very stable, showing only 36% and 8% loss in activities respectively after 3 days of incubation at 50 degrees C. In contrast, beta-glucosidase was significantly less stable retaining only 22.30% activity after 30 min incubation at 40 degrees C. The glucanases manifested maximum stability in pH range of 5.5-6.0 whereas beta-glucosidase was completely stable over a broad pH range of 6.5-9.0. Both glucanases were enhanced by some cations whereas beta-glucosidase did not require any cation for activity. K(m) values for crude exoglucanase, endoglucanase and beta-glucosidase were 40.00 mg/ml, 92.30 mg/ml and 1.714 mM with maximum reaction velocities (Vmax) of 0.606, 33.330 and 0.109 IU/mg of protein, respectively. The enzymes were subject to end-product inhibition, with exo- and endo-glucanases decreasing by 20% and 70% respectively, in the presence of 0.3% glucose. However, beta-glucosidase showed marked resistance to glucose inhibition, retaining 59% of residual activity even in the presence of 30% glucose in the reaction mixture. This characteristic may be advantageous in the commercial exploitation of enzyme system. An activation of beta-glucosidase at lower concentrations of glucose suggests competitive inhibition.

The cellulase complex of S. albaduncus was found to undergo catabolite repression in the presence of glycerol accompanied by a decrease in the pH of the medium. The results of the experiments conducted at two different initial pH of the medium suggested that pH effect as well as proteases were involved in the inactivation of glucanases (exoglucanase and endoglucanase) whereas beta-glucosidase inactivation was solely due to 'pH effect'. It was also apparent that pH change followed by the addition of glycerol caused alterations in protease activities as well as pattern of their production.

Thermophilic actinomycetes (TAs) are unique high temperature aerobic bacteria which belong to the group actinomycetes. While working on hypersensitivity pneumonitis (HP), an immunological disorder, resulting from the inhalation of spores of thermophilic actinomycetes, it was considered worthwhile to record their occurrence in the environment of Punjab. Thermophilic actinomycetes isolated by spread plate method from nine different substrates of the Punjab environment were identified as 8 different species. Atmospheric occurrence of TAs was detected by exposing Petri dishes containing soy agar medium which were exposed in six different environments of the state. Seven thermophilic species were recorded. Thermoactinomyces vulgaris was the predominant species with 87.5, 87.1, and 100% prevalence in the soil, natural manure and the wheat field, respectively. The study is the first report of its kind from this region.