Isolation and characterization of carcinogenic chromium reducing bacillus pumilus from tannery effluent of Hazaribag area

Abstract

Hexavalent Chromium, which is a heavy metal appears to be very toxic in nature. It also possesses the carcinogenic and mutagenic property and causes various serious diseases like skin cancer, lung cancer, pulmonary congestion etc. Due to its usefulness it has become a part of various industries like leather, tannery, dye, stainless steel etc. Therefore, they are being freed every day without any treatment and making the natural environment very hazardous for the human health. Chromium is available in two oxidative form from which its trivalent form is less toxic than its hexavalent form. It has become a necessity to reduce the hexavalent Chromium from the natural environment to preserve the earth. Through this study a strain was experimented to identify their ability to reduce hexavalent Chromium to its trivalent form as well as their tolerance to different concentration of Chromium. To conduct this research sample was collected from the Hazaribag tannery area which was then isolated and purified using different protocol. Then this purified strain was experimented using DPCZ based bioassay method to discover their reduction capacity which shows that the strain has good Chromium reduction capacity at 37˚C pH 5.5 and 7 as well as 42˚C, pH 7. Moreover, the strain has gone through the antibiotic resistant profile study to observe their resistance towards antibiotics. From this study it has found that Streptomycin and Kanamycin have a strong effect on this strain whereas some other antibiotics such as Penicillin, Cefixime, and Ceftriaxone do not have any effect on that strain. The tolerance level towards Chromium of the isolate was measured by Minimum Inhibitory Concentration method which reveals that the strain can tolerate up to 18Mm of Chromium concentration in its surroundings. In addition, to identify the strain, 16s rDNA sequencing was done and using the sequence data a phylogenetic tree was made using different software that shows resemblance between the experimental strain 4W100 and Bacillus pumilus. Cr (VI) is increasing every single day in natural environment as they are not treated properly prior to its discharge. It has now become a necessity to reduce the hexavalent Chromium from the water and soil. This study design will aid in the identification of Chromium reducing bacteria thorough bioremediation method which may play a role in reducing hexavalent Chromium in future.