Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Role of Heavy Metal Resistant Ochrobactrum sp. and Bacillus spp. Strains in Bioremediation of a Rice Cultivar and Their PGPR Like Activities: Sanjeev Pandey , Pallab Kumar Ghosh , Sisir Ghosh , Tarun Kumar De , Tushar Kanti Maiti; J. Microbiol. 2013;51(1):11-17. Published online March 2, 2013; DOI: https://doi.org/10.1007/s12275-013-2330-7

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Abstract: The present study demonstrates the metal toxicity ameliorating and growth promoting abilities of three different bacterial isolates when applied to rice as host plant. The three bacterial strains included a cadmium resistant Ochrobactrum sp., a lead resistant Bacillus sp. and an arsenic resistant Bacillus sp. designated as CdSP9, PbSP6, and AsSP9, respectively. When these isolates were used as inocula applied to metaltreated rice plants of variety Satabdi, the germination percentage, relative root elongation (RRE), amylase and protease activities were increased. The toxic effect of metal was reduced in presence of these bacteria. The overall biomass and root/shoot ratio were also enhanced by bacterial inoculation. Hydroponic studies showed that the superoxide dismutase (SOD) activity and malondialdehyde (MDA) level, which had been increased in the presence of metal stress in rice roots, were lowered by the bacterial inoculation. In addition, all three strains were 1-aminocyclopropane-1-carboxylate (ACC) deaminase and catalase positive, whereas siderophore producing ability was lacking in PbSP6. However, both PbSP6 and AsSP9 were protease positive and could hydrolyse starch. The data indicate that these bacteria have promise for bioremediation as well as for plant growth promotion.

Iron Homeostasis in Brucella abortus: the Role of Bacterioferritin: Marta A. Almirón , Rodolfo A. Ugalde; J. Microbiol. 2010;48(5):668-673. Published online November 3, 2010; DOI: https://doi.org/10.1007/s12275-010-0145-3

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Abstract: Brucella abortus is the etiological agent of bovine brucellosis, an infectious disease of humans and cattle. Its pathogenesis is mainly based on its ability to survive and multiply inside macrophages. It has been demonstrated that if B. abortus ferrochelatase cannot incorporate iron into protoporphyrin IX to synthesize heme, the intracellular replication and virulence in mice is highly attenuated. Therefore, it can be hypothesized that the unavailability of iron could lead to the same attenuation in B. abortus pathogenicity. Thus, the purpose of this work was to obtain a B. abortus derivative unable to keep an internal iron pool and test its ability to replicate under iron limitation. To achieve this, we searched for iron-storage proteins in the genome of brucellae and found bacterioferritin (Bfr) as the sole ferritin encoded. Then, a B. abortus bfr mutant was built up and its capacity to store iron and replicate under iron limitation was investigated. Results indicated that B. abortus Bfr accounts for 70% of the intracellular iron content. Under iron limitation, the bfr mutant suffered from enhanced iron restriction with respect to wild type according to its growth retardation pattern, enhanced sensitivity to oxidative stress, accelerated production of siderophores, and altered expression of membrane proteins. Nonetheless, the bfr mutant was able to adapt and replicate even inside eukaryotic cells, indicating that B. abortus responds to internal iron starvation before sensing external iron availability. This suggests an active role of Bfr in controlling iron homeostasis through the availability of Bfr-bound iron.

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