Rama Bhadekar

Fatty acid profiles of PUFA producing Antarctic bacteria: correlation with RAPD analysis

The significance of polyunsaturated fatty acids (PUFA) to humans lies in their biological activity, as precursors for groups of nutritionally important compounds and as essential cellular components. They are also crucial in animals for the proper development of retinal and nervous tissue. In this work, Antarctic sea samples were used to isolate bacterial cultures producing PUFA. Three bacterial strains were isolated from three different samples and they were named as BRI 1, BRI 7 and BRI 28. Percentage of eicosapentaenoic acid (EPA) was 42.7 and 42.6 of total fatty acids in BRI 7 and 28 respectively. Whereas, docosahexaenoic acid (DHA) (1.4%) was detected only in BRI 28. BRI 7 and 28 showed considerable similarities in their fatty acid profiles, hence these three isolates were further used for random amplification of polymorphic DNA (RAPD) analysis using nine random primers to confirm their genetic relatedness. In contrast to fatty acid profiles, maximum polymorphism (58%) was obtained between BRI 7 and 28, while maximum monomorphism (83.63%) was observed between BRI 1 and 7. Our results indicate that, although the conservation of PUFA genes may point to their potential utilization as phylogenetic markers in culture-independent ecological studies, the biosynthetic diversity of bacterial PUFA production has yet to be fully described.

Novel Staphylococcus sp. isolated from wall scrapings of a historical building in India

Recently, there has been increased interest in the preservation of historic monuments, and considerable effort is being employed in developing new methods for controlling weathering, especially biologically influenced deterioration. Increasing our knowledge about the types of organisms growing on facades will help us to prevent undesirable growth on these structures. This report describes isolation and characterization of a halotolerant bacterium isolated from wall scrapings of a historical building. This organism grew well in SM basal salt medium and nitrogen-free semi-solid LGI medium, and tolerated (1) high temperature (up to 55°C), (2) high salt concentration (20%), and (3) a wide range of pH (5.0-12.0). On the basis of its morphological attributes, biochemical characteristics and partial sequencing of 16S rRNA, it belonged to the genus Staphylococcus with 99% identity to Staphylococcus saprophyticus.

EXTRACELLULAR POLYMERIC SUBSTANCE (EPS) FROM KOCURIA SP. BRI 36: A KEY COMPONENT IN HEAVY METAL RESISTANCE

Objective: Evaluation of Extracellular Polymeric Substance (EPS) induced heavy metal tolerance in Kocuria sp. BRI 36. Methods: Initially, the effect of different concentrations of glucose (1-10 %) on EPS production by BRI 36 was examined. At optimum glucose concentrations, EPS levels were measured by varying heavy metal concentrations (10-50 ppm) of Pb 2+ , Cd 2+ and Cr 3+ . Maximum tolerable concentration (MTC) and survival percentage of BRI 36 were determined under conditions that support EPS synthesis. Comparative analysis of extracted crude EPS was performed by Fourier Transform Infrared Spectroscopy (FTIR) to establish functional groups involved in the metal interaction. Results: Kocuria sp. BRI 36 produced maximum EPS (1g/l) at 5% glucose. Increase in EPS production up to 89% (considering 1g/l as 100%) with an increase in concentrations of heavy metals up to 40 ppm. MTC levels of BRI 36 for heavy metals increased up to 700 ppm when it was cultivated in presence of 5% glucose indicating a major role of surface polymer in metal adsorption. The function of EPS as a protective cover was also evident from an increase in survival percentage of BRI 36 up to 39.4 at MTC. Comparative analysis of extracted crude EPS by FTIR revealed the involvement of O-H, C=O, and C-O-C groups in metal adsorption Conclusion: Antarctic oceanic isolate Kocuria sp. BRI 36 has an ability to produced EPS under stress conditions of heavy metals. Simultaneously, its MTC values increased due to increase in EPS levels. These observations suggest the possibility to develop gentle, environmentally safe and cost-effective method for heavy metal removal.

Statistical Approach for Production of PUFA from Kocuria sp. BRI 35 Isolated from Marine Water Sample

In this study, Plackett-Burman design was used to identify the most influential parameters affecting PUFA production by Kocuria sp. BRI 35 isolated from Antarctic water sample. Amongst 10 variables evaluated, magnesium chloride, protease peptone, glucose, and temperature were significant. Response surface methodology consisting of a central composite design was developed to study the interactions between the variables and to determine optimal values of significant variables. A quadratic model (R = 0.9652, F = 14.64, P < 0.0001) was built. The contour plots indicated that the isolate produced maximum PUFA at lower concentrations of magnesium sulfate (0.9 g/L) and higher concentrations of protease peptone (5 g/L) and glucose (10 g/L) at 15°C. MgSO4 and glucose exhibited quadratic as well as interactive effect on PUFA production whereas protease peptone and temperature showed interactive effects only. After optimization, PUFA production per unit biomass increased from 0.94 mg/g to 11.12 mg/g. This represented an increase from 3% to 58.62% of the total fatty acids. Among PUFAs, the yield of ω-6 fatty acids increased from 9.66 mg/L to 107.71 mg/L with significant increase in linoleic acid (20.36 mg/L) whereas ω-3 fatty acids increased up to 12.37 mg/L with DHA being the major ω-3 fatty acid produced.

Dielectric Barrier Discharge Plasma for Endodontic Treatment

Recently Dielectric Barrier Discharge plasma is being explored for its application as an alternative to the conventional sterilization and disinfection techniques in medical sciences. Dielectric barrier discharge plasma torch has been developed to study the interaction of plasma and effect of its treatment on the growth rate of S. aures, Escherichia coli, Bacillus subtilis and E. faecalis. Plasma treated E. faecalis was compared with Chlorhexidine treated cultures and biofilms of E. faecalis. The results are analysed for significance (P < 0.001) using ANOVA and TUCKEY’s test. In-situ optical emission spectroscopy has been employed to identify the plasma species interacting with the bioculture and biofilm. Based on its efficient disinfecting properties dielectric barrier discharge plasma has been proved to be a promising alternative to traditional techniques used for sterilization during the endodontic treatment.