Abstract
This study was carried out to isolate, screen and characterize arsenic (As) resistant bacteria from As contaminated soils of Dumrakandi and Matlab under Faridpur and Chandpur districts and to evaluate their efficiency in reducing As toxicity against rice seedlings during germination. Thirteen strains were isolated from the soils which showed resistance to different levels of sodium arsenite (viz. 5, 10, 20 and 40 mM) in both agar plate and broth assay using BSMY I media. Among the isolates, BTL0011, BTL0012, BTL0015 and BTL0022 showed highest resistance to 40 mM sodium arsenite. Gram staining and KOH solubility test revealed that five strains were gram positive and rest eight was gram negative. They grew well in the liquid media at pH 5.5 to 8.5. In-vitro rice seedling bioassay with two superior isolates (BTL0011 and BTL0022) revealed that As resistant strains significantly enhanced seed germination of BRRI dhan29 and BRRI dhan47 at 60 ppm As. This study was laid out in CRD with three replications. The performance of BTL 0022 was superior to BTL0011. The overall results suggest that BTL0011 and BTL0022 can be used for bioremediation of As contaminated soils and to increase the germination and seedling growth of rice in As contaminated soils.Res. Agric., Livest. Fish.2(2): 229-237, August 2015
Highlights
Arsenic (As), which have carcinogenic, mutagenic and teratogenic properties is a major constituent in more than 245 minerals and is ubiquitous in the environment (Mandal and Suzuki, 2002)
Isolation of arsenic resistant bacteria from the contaminated soils Thirteen bacterial strains were isolated at different sodium-arsenite concentrations
The results of the present study clearly showed that more germination and seedling growth advantages of rice seed could be achieved by bacterial inoculation under arsenic toxicity condition
Summary
Arsenic (As), which have carcinogenic, mutagenic and teratogenic properties is a major constituent in more than 245 minerals and is ubiquitous in the environment (Mandal and Suzuki, 2002) It is found responsible for bladder, kidney, liver, lung, and skin cancers and is listed as a class A human carcinogen by the USEPA (Chen et al, 2002). Ion exchange, adsorption with activated alumina and activated carbon, ultrafiltration, reverse osmosis, and complexation with metal ions followed by coagulation These physic-chemical treatment methods require large amount of chemical reagents that are expensive and may result secondary environmental pollution. Due to these apparent disadvantages of the above physico-chemical treatments, novel techniques for the reduction of contaminant toxicity with minimizing cost have been proposed. This study was designed to isolate and screen As resistant bacteria from the As contaminated soil and to examine effects of As resistant bacteria on seed germination and seedling growth of rice under arsenic contaminations
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