Use of Indigenous Bacteria from Arsenic Contaminated Soil for Arsenic Bioremediation - Management of Natural Resources in a Changing Environment - page 153

Table 1 Phenotypic and biochemical c haracteristics of the isolate KUMAs1

Biochemical features and carbon source utilization
Negative

Colony features
on NA a Cell morphology Positive

Off-white Gram positive Catalase /Amylase activities Mannitol

utilization

Punctiform Rod shaped Starch hydrolysis IAA production

Smooth Motile Methyl red test

Convex with
entire edge

Endospore-
forming H 2 S
production

Carbohydrate fermentation (glucose/
fructose/lactose/ sucrose)

Voges-Proskauer test
P-solubilization
Citrate utilization
Siderophore production

a NA = Nutrient agar medium

Isolation and Characterization of As Resistant Bacteria

The isolated bacterial strain KUMAs1 was found to be gram-positive rod shaped,
endospore forming and motile in nature. Morphological and biochemical features of
KUMAs1 have been summarized in Table 1 . Based on the biochemical tests and
analysis of the 16S rDNA sequence (~1,309 bp) using BLAST function at NCBI
database and Ribosomal Database Project, the isolate KUMAs1 was identifi ed as a
strain of Brevibacillus sp. (NCBI GenBank Accession No. KC460322). The phylo-
genetic lineage of KUMAs1 was constructed from 16S rDNA sequence using
MEGA 4.0 (Fig. 2 ).

Toxic Metal and Antibiotic Sensitivity of KUMAs1

KUMAs1 showed varied degree of resistance to different heavy metals including
arsenic and the order of toxicity in both the NB and MB was found to be Co > Zn >
Cd > Ni > Cr >As(III) >As(V). Respective MIC values of different heavy metals
tested are given in Table 2 . The differences in MIC values in NB and MB might be
attributed by the fact that metal bioavailability was reduced due to complexation
with undefi ned components in the NB medium (Chatterjee et al. 2009 ); for the same
reason magnitude of As resistance was found to be more in solidifi ed medium. The
bacterial strain was found to be sensitive to most of the antibiotics tested (Table 3 )
that offers the scope for using it as suitable bioremediating candidate, as there are
many reports suggesting that metal contamination in natural environments could
have an important role in the maintenance and proliferation of antibiotic resistance
(Summers 2002 ).