Abstract:Nature (Bauer AW 1966) The main objective of

Abstract:Nature is very
diverse particularly with respect to microbial flora. Soil is the richest
source of microbes and shows extreme diversity in group of prokaryotes and
lower eukaryotes.  Mine area soil are not
very favourable for all prototypes to grow and adapt in unusual physiochemical
conditions prevailing in them. Bacteria belongs to such metal enriched areas
shows distinct ability to adjust themselves in such toxic environment by
different mechanisms like adsorption, accumulation, uptake of reduction (of
such toxic elements/metals).  (DH. 1999). Chromium is an important metal and widely used in
industries like wood preservation, Leather tanning, steel industries etc. Since
every day there is an occurrence of new infections and diseases so it is very
essential to study the antibiotic sensitivity of bacteria isolated. (Ali Akbar Safari Sinegani 2017)The
Kirby-Bauer disc-diffusion method was used to obtain antibiotic resistance
patterns of these isolates. (Bauer AW 1966) The main
objective of this study was to determine the relationship
between the antibiotic and heavy metal tolerance of culturable bacteria
isolated from mine area.    Introduction:Metals are the important constituents of the earth’s
crust. From the time it was evolved, metals play a key role in development of
human beings. There are different sources of metals in the environment. In trace amount,
metals also play an important role in many metabolic processes as well as in
growth and development of animals, plants and Microorganisms. Heavy metals are
the group of metals and metalloids with atomic density greater than 4g/cm3, or 5
times or more, greater than water and are toxic even at low concentration (Hutton 1986) (Battarbee 1988) (Nriagu 1989); (Garbarino 1995) (Hawkes 1997) . Excessive use of
these heavy metals for Industrial development
leads to increase in heavy metal concentration in environment which directly
affect humans, plants, animals and microbial habitat. (Bergey DH 1994) (Beveridge TJ
1989) Elevated levels of toxic metals in the environment have
great impact on microbial
communities by affecting their growth, Morphology, biochemical activities
resulting in the development of metal resistant populations (Mahler I 1986). Intensive human activity and exploitation of natural deposits
i.e. mining are the main causes for the expansion of metal-resistant micro-organisms.
Various microbes have adapted the presence of metals mechanisms like use
of chromosome, plasmid, or transposon-encoded, metal resistance mechanisms. (Bruins 2000)To
deal with such toxic conditions microorganisms adapt some biological
mechanisms. Microbes belongs to such heavy metal enriched areas shows distinct
ability to adjust themselves in such toxic environment by different mechanisms
like Oxidation, adsorption, accumulation, uptake and reduction of the metal
ions to a less toxic state. (DH. 1999). Chromium
is an industrially important heavy metal and is mined as
chromite. It is a strong oxidant, Crystalline; steel-grey, lustrous, hard
metallic, is an odourless. Found in rocks, animals, plants, and soil. It get
released in environment by a large number of industrial activities such as
electroplating, chromate manufacturing, and
tanning of animal hides in leather industry, dyes and pigment fabrication and
in wood preservation. (R.Bakiyaraj 2014) . Chromium present
in different oxidation state but most common are Cr (III) and Cr (IV).  Trivalent chromium Cr (III) is less toxic and
in small concentrations, appears to be an essential nutrient for plant, animal
and human life (Jerome O. Nriagu 1988) and has been shown
to be involved in glucose and lipid metabolism in mammals. (RA 1989). Whereas Hexavalent
chromium and its compounds Cr (IV) are mutagenic as well as carcinogenic (Lee JM 2008)  Due to soluble nature it may persist in water
for a long period of time and easily spread in environment and have adverse
effect on plants , animals and microbial flora. Chromium VI can reduced
to Cr III in presence of many reducing agents. Though many physiochemical
processes are exits for the removal of Cr (VI) from environment but these
methods are very costly and have some limitations. So there is a need of
eco-friendly and cost effective methods. (Ahluwalia SS
2007)
(Zahoor A 2009).  Use of metal tolerant/ reducing bacteria for
Bioremediation of such toxic metals is better alternative. (Ozturk S 2009) (He Z 2009). Many chromium
tolerant bacterial strains have been reported including Pseudomonas species (V. V. Konovalova 2003) (A. Ganguli and A. K.
Tripathi 1999)
(C. Garbisu 1998), Desulphovibiro spp (Michel 2001) Enterobacter spp
(P. M. Wang 1990) Escherichia coli (Wang 1993) , Bacillus spp (Chaturvedi 2011) and several other
bacterial isolates.In current
study, we have isolated chromium tolerant bacteria from chromite mine area in
Bhandara and Nagpur District, Maharashtra, and analyse their growth at
different concentrations of chromium and antibiotic susceptibility of those
isolates. Materials and Methods:Site description and soil sampling:The aim of the
present study was to isolate tolerant bacteria from chromium enriched soil, so as
per the report of Directorate of Geology and Mining, Government of Maharashtra
Nagpur, we have selected chromite reserves from Pauni, Bhandara district and
Taka from Nagpur district, Maharashtra. Soil sampling
sites were selected using previous investigations regarding chromite mineralization.  Collected Samples were subjected to X-
ray fluorescence analysis from IBM Mineral testing Lab,
Nagpur for determination of chromium concentration. Soil pH, electrical
conductivity, Organic carbon content, Total Nitrogen (Kjeldhal method),
available Phosphorus & Potassium were also studied. Isolation of Chromium Tolerant Strains:In order to
isolate tolerant species, serial
dilution and enrichment culture techniques were used. For serial
dilution, soil samples were diluted in 1:10 w/v in sterile distilled water and
inoculated on Luria Bertani agar containing 50 ppm of K2Cr2O7. Plates were
incubated at 37 ºC for 24-48 hrs. For Enrichment Culture Technique, 5 ml of
soil suspension was added to minimal media (50 ml) containing 20 ppm of K2Cr2O7
and then incubated 37 ºC for 10 days.
Individual bacterial colonies showing Cr resistance were picked and
cultured in LB media get pure culture and were preserved for further use.  All these isolates were further proceed for colonial,
Morphological, Biochemical and molecular characterization.