SUNITA BORKAR, YOGITA NAGARSEKAR AND SAROJ BHOSLE
Abstract
Bacterial isolates growing at pH 10.5 were enumerated and isolated from spent water samples of an Agrochemical factory in Goa. The counts were much higher when serial dilutions were prepared in sodium carbonatebicarbonate buffer (pH 10.0) than when physiological saline was used as a diluent. Further, Polypeptone yeast extract glucose agar (PPYG) showed higher counts of organisms growing at pH 10.5 as compared to Horikoshi I and II media. Amongst the 60 bacterial isolates, 60% were found to be Alkaliphilic and 40% were Alkalitolerant. All the cultures were Gram positive with 100% isolates being catalase positive, 31% being oxidase positive and 42% showing pigment formation. The distribution indicated 75% of Bacillus, 18% of Micrococcus and 7% of Coryneform genera. Alkaliphilic property was found to be prevalent in Bacillus and Micrococcus species while alkalitolerant property was detected among Bacillus and Coryneforin genera. Studies on buffering capacity of Bacillus, Micrococcus and Coryneforni genera reflected that the alkaliphilic Bacillus sps. is capable of significantly controlling the change in external pH with the change of one pH unit arising after addition of more than 300 Pls of 0.05 M KOH. This property is lost when the cells are treated with Triton X-100. However, the alkalitolerant culture Corynebacterium depicted a pH control even after treatment with Triton X-100.