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

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.

The Photodynamic Effect of Methylene Blue and Toluidine Blue on Candida albicans Is Dependent on Medium Conditions: Gabriela Guimarães Carvalho , Monalisa Poliana Felipe , Maricilia Silva Costa; J. Microbiol. 2009;47(5):619-623. Published online October 24, 2009; DOI: https://doi.org/10.1007/s12275-009-0059-0

Abstract: Due to the increased number of immunocompromised patients, the infections associated with the pathogen of the genus Candida and other fungi have increased dramatically. Photodynamic antimicrobial chemotherapy (PACT) has been presented as a potential antimicrobial therapy, in a process that combines light and a photosensitizing drug, which promotes a phototoxic response by the treated cells. In this work, we studied the effects of the different medium conditions during PACT, using either methylene blue (MB) or toluidine blue (TB) on Candida albicans. The inhibition of the growth produced by PACT was decreased for different pH values (6.0, 7.0, and 8.0) in a buffered medium. The phototoxic effects were observed only in the presence of saline (not buffered medium). PACT was modulated by calcium in a different manner using either MB or TB. Also when using MB both verapamil or sodium azide were able to decrease the phototoxic effects on the C. albicans. These results show that PACT is presented as a new and promising antifungal therapy, however, new studies are necessary to understand the mechanism by which this event occurs.

Characterization of Plant-Growth Promoting Diazotrophic Bacteria Isolated from Field Grown Chinese Cabbage under Different Fertilization Conditions: Woo-Jong Yim , Selvaraj Poonguzhali , Munusamy Madhaiyan , Pitchai Palaniappan , M. A. Siddikee , Tongmin Sa; J. Microbiol. 2009;47(2):147-155. Published online May 2, 2009; DOI: https://doi.org/10.1007/s12275-008-0201-4

Abstract: Diazotrophic bacteria isolated from the rhizosphere of Chinese cabbage were assessed for other plant growth promoting characteristics viz., production of IAA, ethylene, ACC deaminase, phosphate solubilization, and gnotobiotic root elongation. Their effect on inoculation to Chinese cabbage was also observed under growth chamber conditions. A total of 19 strains that showed higher nitrogenase activity identified by 16S rRNA gene sequence analysis were found to be the members of the genera Pseudomonas and Agrobacterium belonging to α- and γ-Proteobacteria groups. These strains were also efficient in producing IAA and ACC deaminase though they produced low levels of ethylene and no phosphate solubilization. In addition, inoculation of selected diazotrophic bacterial strains significantly increased seedling length, dry weight, and total nitrogen when compared to uninoculated control. The colonization of crop plants by diazotrophic bacteria can be affected by many biotic and abiotic factors, and further studies are oriented towards investigating the factors that could influence the establishment of a selected bacterial community.

Differential Response of Etiolated Pea Seedlings to Inoculation with Rhizobacteria Capable of Utilizing 1-Aminocyclopropane-1-Carboxylate or L-Methionine: Baby Shaharoona , Muhammad Arshad , Azeem Khalid; J. Microbiol. 2007;45(1):15-20.; DOI: https://doi.org/2497 [pii]

Abstract: The majority of soil microorganisms can derive ethylene from L-methionine (L-MET), while some rhizobacteria can hydrolyze 1-aminocyclopropane-1-carboxylate (ACC) due to their ACC-deaminase activity. In this study, three strains having either ACC-deaminase activity (Pseudomonas putida biotype A, A7), or the ability to produce ethylene from L-MET (Acinetobacter calcoaceticus, M9) or both (Pseudomonas fluorescens, AM3) were used for inoculation. The highly ethylene specific bioassay of a classical “triple” response in pea seedlings was used to investigate the effect of the inoculation with the rhizobacteria in the presence of 10 mM ACC or L-MET. The exogenous application of ACC had a concentration-dependent effect on the etiolated pea seedlings in creating the classical “triple” response. The inoculation with P. putida diluted the effect of ACC, which was most likely due to its ACC-deaminase activity. Similarly, the application of Co2+ reduced the ACC-imposed effect on etiolated pea seedlings. In contrast, the inoculation of A. calcoaceticus or P. fluorescens in the presence of L-MET caused a stronger classical “triple” response in etiolated pea seedlings; most likely by producing ethylene from L-MET. This is the first study, to our knowledge, reporting on the comparative effect of rhizobacteria capable of utilizing ACC vs L-MET on etiolated pea seedlings.

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