Production of extracellular proteases and amylases by some acidophilic and alkalophilic bacteria.

Twelve bacteria were isolated from two effluent sources of Shaw-Wallace Gelatins, Jabalpur. Six bacteria from dicalcium phosphate plant effluent (pH-5) and six from main drain of the factory (pH-10) were isolated. Two facultatively acidophilic and two facultatively alkalophilic bacteria were selected and tentatively identified as Plesiomonas shigelloides, Aeromonas hydrophilla, Klebsiella pneumoniae and Staphylococcus saprophyticus respectively. Acidic amylases were produced in higher amounts on 4th day of incubation by Plesiomonas shigelloides and on 6th day by Aeromonas hydrophilla. Alkaline amylases were produced in higher amounts on 4th day of incubation by Klebsiella pneumoniae and on 8th day by Staphylococcus saprophyticus in vitro.

Characteristics of extracellular proteases produced by Bacillus laterosporus and Flavobacterium sp. isolated from gelatinfactory effluents.

Forty bacterial isolates from the effluents of a gelatin factory (Jabalpur, India) were screened for protease activity and the two most potent producers were identified as Bacillus laterosporus and a Flavobacterium sp. The enzymes of both isolates were optimal at pH 8 and 60°C, with maximum activity after 90 min. The enzyme activity of B. laterosporus was suppressed by Fe(2+), Mg(2+), Mn(2+) and Zn(2+) ions but was enhanced by Ba(2+) and Ca(2+). That of Flavobacterium sp. was suppressed by Mg(2+) and Mn(2+) ions but enhanced by Ba(2+), Ca(2+) and Fe(2+). The enzyme activity of the former was strongly inhibited by KCN, whereas that of the latter was only slightly inhibited by 8-hydroxyquinoline.

Mutational analysis of the NH4+-nitrogen controls that regulate ammonium transport activity, heterocyst differentiation, nitrogenase activity and the heterocyst-spacing pattern in the cyanobacterium Nostoc muscorum.

Mutational analysis of the genetic determinants mediating NH(4+)-nitrogen regulating effects on NH(4+)-transport activity, heterocyst differentiation, nitrogenase activity and heterocyst pattern formation was carried out in Nostoc muscorum. Evidence suggested the operation of three separate genetic determinants in such nitrogen control; one mediating NH(4+)-repression control on both heterocyst formation and NH(4+)-transport activity, a second (Nif-R) mediating NH(4+)-repression control on nitrogenase synthesis/activity and a third (Pat-R) essential for intercalary heterocyst formation/distribution. Ammonia itself functioned as repressor signal of heterocyst formation and nitrogenase synthesis/activity and the glutamine synthetase enzyme played no role in the repression/derepression control of heterocyst development and functional nitrogenase formation.

Purification and partial characterization of two extracellular keratinases of Scopulariopsis brevicaulis.

Two extracellular keratinases of Scopulariopsis brevicaulis were purified and partially characterized. The enzymes were isolated by the techniques of gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). These keratinases (K I & K II) were purified approximately 33 and 29 fold, respectively. SDS-PAGE of the products of gel filtration chromatography (K I & II) produced only one band each, suggesting homogeneity. The optimum pH for both keratinases was 7.8, while the optimum temperatures were 40 degrees C (K I) and 35 degrees C (K II). Estimated molecular weights were 40-45 KDa and 24-29 KDa for K I & K II respectively. Both keratinases were inhibited by phenylmethylsulfonyl fluoride which suggests a serine residue at or near an active site.

Keratinolysis by Absidia cylindrospora and Rhizomucor pusillus: biochemical proof.

Absidia cylindrospora and Rhizomucor pusillus causal agents of phycomycoses, were cultured on sterile natural keratins in a mineral solution and the keratin degradation products analyzed. The excess of sulphur was removed by oxidation to inorganic sulphate and thiosulphate, which were the main products of sulphitolysis of keratin. The proteolytic activity of the two fungi depended on the nature of the keratin substrate. Human scalp hair was the most favoured keratin substrate by both the fungi.

Evaluation of keratinolytic potential of some fungal isolates from gelatin factory campus.

During hair degradation, majority of organic sulphur was oxidized to inorganic sulphate and thiosulphate by four fungal isolates (Cylindrocarpon lichenicola, Graphium cuneiferum, Microsporum gypseum, and M. fulvum) from gelatin factory soil. Inorganic thiosulphate, an unusual metabolite, was regularly detected in the culture filtrates of all fungi, although in less amounts. Maximum quantity (44 micrograms/ml) was released by G. cuneiferum on 50th day of incubation. All four fungi showed significant extracellular keratinase activity on human hair. Sulphydryl compounds were present in low amounts throughout the experiment. Detection of inorganic sulphate and thiosulphate with significant release of total protein and keratinase and changes in alkalinity, established the role of sulphitolysis and peptidolysis during keratin biodegradation by fungi which ultimately results in complete keratin degradation.