Lakshmanan Kannan

Isolation and characterization of phosphate-solubilizing bacteria from seagrass rhizosphere soil

Phosphate-solubilizing bacterial strains (6 Nos.) were isolated from the rhizosphere soils of two seagrasses (Halophila ovalis (R. Br.) Hook and Halodule pinifolia (Miki) Hartog) in the Vellar estuary. Experimental studies found that the strain PSSG6 was effective in phosphate solubilization with Phosphate Solubilization efficiency index E = 375 ± 8.54, followed by the strain PSSG5 with Phosphate Solubilization efficiency index E = 275 ± 27.3. Of the 6 strains isolated, the strains PSSG4 and PSSG5 belonged to the genus Bacillus, and PSSG1, PSSG2 and PSSG3 were identified as Citrobacter sp., Shigella sp., and Klebsiella sp., respectively, by conventional method, and PSSG6 was identified as Bacillus circulans using conventional and molecular methods.

Statistical optimization and anticancer activity of a red pigment isolated from Streptomyces sp. PM4

OBJECTIVE To enhance the pigment production by Streptomyces sp. PM4 for evaluating its anticancer activity. METHODS Response surface methodology was employed to enhance the production of red pigment from Streptomyces sp. PM4. Optimized pigment was purified and evaluated for the anticancer activity against HT1080, Hep2, HeLa and MCF7 cell lines by MTT assay. RESULTS Based on the response surface methodology, it could be concluded that maltose (4.06 g), peptone (7.34 g), yeast extract (4.34 g) and tyrosine (2.89 g) were required for the maximum production of pigment (1.68 g/L) by the Streptomyces sp. PM4. Optimization of the medium with the above tested features increased the pigment yield by 4.6 fold. Pigment showed the potential anticancer activity against HT1080, HEp-2, HeLa and MCF-7 cell lines with the IC50 value of 18.5, 15.3, 9.6 and 8.5 respectively. CONCLUSIONS The study revealed that the maximum amount of pigment could be produced to treat cancer.

Response surface methodology for the optimization of α-amylase production by Streptomyces sp. ML12 using agricultural byproducts

Amylases constitute one of the most important groups of enzymes for commercial use. In the present study, production of α-amylase was optimized using a newly isolated actinobacterial strain from the coral reef environment of the Gulf of Mannar Biosphere Reserve, India. It was identified as Streptomyces sp. ML12 based on chemotaxonomy, cultural and morphological characteristics, carbon source utilization and 16S rRNA gene sequencing. Fermentation variables were selected in accordance with the Plackett-Burman design and were optimized by response surface methodology. Five significant variables (rice bran and wheat bran — both agricultural byproducts, sodium chloride, magnesium sulphate and incubation period) were selected for the optimization via central composite design. The optimal features were rice bran (5.5 g/100 mL), wheat bran (5.3 g/100 mL), sodium chloride (2.8 g/100 mL), magnesium sulphate (1.4 g/100 mL) and 8 days of incubation period. Optimization of the medium with the above tested features increased the amylase yield by 4.4-fold.

Long-time shoreline monitoring of the vellar estuarine complex, southeast coast of India: Using multispectral satellite data

The present study was carried out to track the path of Vellar estuary over a period of 38 years (1970–2008) and also to detect the impact of tsunami on estuarine complex of the Vellar estuary. Visual interpretation techniques were employed by using multispectral data of Landsat TM (1991) and IRS-P6 LISS III (2004, 2006, and 2008) to delineate shoreline changes in the Vellar estuarine complex. Results clearly revealed the changes that occurred along the estuarine path over the period, and severe erosion was noticed in the seaward side of the MGR Thittu and accretion, along the estuarine mouth. It is also visible that there is clear river path shift in the river course. Although the sandbar formation was seen with only little morphologic modification up to 2004, the Indian Ocean tsunami that struck this coast (26 December, 2004) distorted the sandbar of the Vellar estuarine mouth; however, the 2006 satellite images confirmed that the sandbar was formed again to its original structure as that of before the tsunami.