Gangatharan Muralitharan

Isolation and screening of heterocystous cyanobacterial strains for biodiesel production by evaluating the fuel properties from fatty acid methyl ester (FAME) profiles.

This study reports on the biodiesel quality parameters of eleven heterocystous cyanobacterial strains based on fatty acid methyl esters (FAME) profiles. The biomass productivity of the tested cyanobacterial strains ranged from 9.33 to 20.67 mg L(-1) d(-1) while the lipid productivity varied between 0.65 and 2.358 mg L(-1) d(-1). The highest biomass and lipid productivity was observed for Calothrix sp. MBDU 013 but its lipid content is only 11.221 in terms of percent dry weight, next to the Anabaena sphaerica MBDU 105, whose lipid content is high. To identify the most competent isolate, a multi-criteria decision analyses (MCDA) was performed by including the key chemical and physical parameters of biodiesel calculated from FAME profiles. The isolate A.sphaerica MBDU 105 is the most promising biodiesel feed stock based on decision vector through Preference Ranking Organisation Method for Enrichment Evaluation (PROMETHEE) and Graphical Analysis for Interactive Assistance (GAIA) analysis.

Morphological and genetic diversity of symbiotic cyanobacteria from cycads

The morphological and genetic diversity of cyanobacteria associated with cycads was examined using PCR amplification techniques and 16S rRNA gene sequence analysis. Eighteen symbiotic cyanobacteria were isolated from different cycad species. One of the symbiotic isolates was a species of Calothrix, a genus not previously reported to form symbioses with Cycadaceae family, and the remainder were Nostoc spp. Axenic cyanobacterial strains were compared by DNA amplification using PCR with either short arbitrary primers or primers specific for the repetitive sequences. Based on fingerprint patterns and phenograms, it was revealed that cyanobacterial symbionts exhibit important genetic diversity among host plants, both within and between cycad populations. A phylogenetic analysis based on 16S rRNA gene sequence analysis revealed that most of the symbiotic cyanobacterial isolates fell into well‐separated clades. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Screening of a hypersaline cyanobacterium, Phormidium tenue, for the degradation of aromatic hydrocarbons: naphthalene and anthracene

Hypersaline Phormidium strains were grown in media amended with naphthalene and anthracene. Phormidium tenue was identified as tolerating and effectively degrading polycyclic aromatic hydrocarbons that may be toxic in the environment. GC/MS analysis explained the degradation of these compounds by P. tenue. A dioxygenase enzyme system was evident by the formation of anthracene dione as the first degradation compound. This strain could be used for bioremediation of polycyclic aromatic hydorcarbon pollution on seashores.

Statistical optimization of exopolysaccharide production by Lactobacillus plantarum NTMI05 and NTMI20.

In this study, 27 strains of Lactic acid bacteria (LAB) were isolated and identified from different milk sources. All the isolates were biochemically characterized and screened for their ability to produce exopolysaccharides (EPS), among which two isolates namely Lactobacillus plantarum NTMI05 (197mg/L) and Lactobacillus plantarum NTMI20 (187mg/L) showed higher EPS production. Both the isolates were molecular characterized and tested for their probiotic properties. The chemical composition of EPS from L. plantarum NTMI05 and NTMI20 revealed the presence of 95.45% and 92.35% carbohydrates, 14±0.1and 11±0.15mg/L lactic acid, 10.5±0.2 and 9±0.1mg/mL of reducing sugar, respectively. HPLC analysis showed galactose at the retention time of 2.29.The maximum EPS yield was optimized for the media components like glucose (20g/L), yeast extract (25g/L) and ammonium sulphate (2g/L) using Central Composite Design and Response Surface Methodology (RSM). Under optimum conditions the predicted maximum EPS production was 0.891g/L, 0.797g/L, while the actual experimental value was 0.956g/L and 0.827g/L for L. plantarum NTMI05 and NTMI20, respectively. The antioxidant capacity was also evaluated by DPPH and reducing power assay proving the potentiality of these organisms in food and dairy industries.

Identification of p-Cresol as an Estrus-Specific Volatile in Buffalo Saliva: Comparative Docking Analysis of Buffalo OBP and β-Lactoglobulin with p-Cresol

Assessment of salivary volatile compounds adopting gas chromatography-linked mass spectrometry (GC-MS) analysis revealed the presence of a total of 11 compounds in the buffalo saliva irrespective of the stages in the reproductive cycle. p-cresol was identified as an estrus-specific volatile compound in the saliva. In addition, modeling of odorant-binding protein (OBP) and &bgr;-lactoglobulin revealed that OBP is highly stable and has strong binding affinity with p-cresol. Hydrogen bond interactions indicated that OBP is responsible for pheromone release through saliva. In contrast, &bgr;-lactoglobulin, which belongs to the same lipocalin family as OBP, possesses less affinity to p-cresol than OBP, suggesting that it is not involved in p-cresol binding and transport. Phylogenetic characterization revealed that bovine family of OBP is separately clustered. It is suggested that p-cresol has the potential to be developed as a biomarker to detect the reproductive status in the buffalo and for behavioral manipulations.

Molecular modeling of ABC transporter system - permease proteins from Microcoleus chthonoplastes PCC 7420 for effective binding against secreted aspartyl proteinases in Candida albicans - a therapeutic intervention.

Secreted aspartyl proteinases (SAP) are the key virulence factors that play a central role in the pathogenesis of Candida albicans and always are the best target for designing potent antifungal agents. Cyanobacteria have already been recognized to provide chemical and pharmacological novelty and diversity over conventional sources of drugs for combating major diseases ranging from AIDS to cancer. In this study, the two ABC transporter systems — permease proteins from Microcoleus chthonoplastes PCC 7420 were modeled and the protein-protein interaction assessment of the modeled proteins with selective secreted aspartyl proteinases of Candida albicans was attempted. The modeled proteins were assigned PMDB IDs PM0077423 and PM0077424. The secreted aspartyl protease 5 of Candida albicans showed effective interaction with ABC transporter permease protein 2 of Microcoleuschthonoplastes PCC 7420. Hydrophobic interactions were found between Tyr, Phe and Pro in chain A and Pro and Tyr in chain B. Our results of the docked complexes clearly demonstrated the potentiality of permease proteins in arresting the virulence nature of SAP of Candida albicans effectively. This study is first of its kind in addressing the therapeutic intervention of virulence nature of Candida albicans by the cyanobacterial system.

Microbial Symbionts of Plants

Plants in nature always grow with soil microorganisms, and some become intimately associated with plants to form mutualistic symbiosis. Examples of such symbiotic microorganisms include mycorrhizal fungi, cyanobacteria, and N2-fixing prokaryotes, especially rhizobia. Looser symbiotic associations involve bacteria and soil microfauna within the rhizosphere. Their metabolic activities increase nutrient availability. All of these symbioses may affect rates of growth and eventually reproduction of plants compared with growth in the absence of such associations. A symbiotic association is therefore a potential selection pressure that can influence the evolutionary success of vascular plants and hence the composition of plant communities. Application of associative bacteria for sustainable agriculture holds immense potential. These bacteria are known to enhance growth and yield of plants by fixing atmospheric nitrogen, solubilization of phosphate, production of phytohormones and siderophores, possession of antagonistic activity, as well as reducing the level of stress ethylene in host plants. This review provides examples of associations and interactions between microorganisms and plants. The cyanobacterial association with various plants such as bryophyte, pteridophyte, gymnosperm, and angiosperm was illustrated. It also describes the actinorhizae, Frankia and Rhizobium, interaction with plants and their applications.

M13-based genotyping of marine cyanobacterial strains from the Indian subcontinent and maintained in the NFMC germplasm collection

The aim of this study was to analyze marine cyanobacterial culture collections strains of the Indian subcontinent at the level below species. This is important to improve the abilities of service culture collections to provide their user community with correctly identified and clean organisms. A total of 50 marine cyanobacterial strains were genotyped with M13 polymerase chain reaction (PCR) fingerprinting to provide diagnostic fingerprints for each culture. Depending on the strains, 9 to 26 bands were observed for the primer tested. Within the species, strains representing different isolates were genetically clearly different. Data obtained from genomic fingerprinting were used to construct binary distance matrix, and the neighbor-joining tree constructed demonstrated the ability of this method to differentiate strains at the intraspecific level. An important and useful result obtained in this study is the application of the M13 PCR fingerprinting method on almost all forms of cyanobacteria for strain and species discrimination.

Growth kinetic and fuel quality parameters as selective criterion for screening biodiesel producing cyanobacterial strains

The efficiency of cyanobacterial strains as biodiesel feedstock varies with the dwelling habitat. Fourteen indigenous heterocystous cyanobacterial strains from rice field ecosystem were screened based on growth kinetic and fuel parameters. The highest biomass productivity was obtained in Nostoc punctiforme MBDU 621 (19.22mg/L/day) followed by Calothrix sp. MBDU 701 (13.43mg/L/day). While lipid productivity and lipid content was highest in Nostoc spongiaeforme MBDU 704 (4.45mg/L/day and 22.5%dwt) followed by Calothrix sp. MBDU 701 (1.54mg/L/day and 10.75%dwt). Among the tested strains, Nostoc spongiaeforme MBDU 704 and Nostoc punctiforme MBDU 621 were selected as promising strains for good quality biodiesel production by Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) and Graphical Analysis for Interactive Assistance (GAIA) analysis.

Unraveling the presence of multi-class toxins from Trichodesmium bloom in the Gulf of Mannar region of the Bay of Bengal

&NA; Trichodesmium is an enigmatic bloom forming, non‐heterocystous cyanobacterium reported most frequently in the coastal waters of India. However, the toxigenic potential of this globally significant N2 fixing cyanobacterium has not been characterized. In this study, we report for the first time the presence of potent multi‐class neurotoxins such as Anatoxin‐a, Saxitoxins, Gonyautoxin and hepatotoxins like MC‐LR, MC‐YA from a bloom material of Trichodesmium sp. MBDU 524 collected at the Gulf of Mannar region. Toxins were determined using liquid chromatography‐electrospray ionization mass spectrometry (LC‐ESI‐MS) analysis of HPLC purified aqueous and solvent fractions. Molecular phylogenetic analysis through 16S rRNA gene sequencing showed the close relationship with Trichodesmium erythraeum clade. The toxigenic potential was validated through brine shrimp toxicity assay and showed 100% mortality after 48 h of incubation. The results suggest the potential toxigenic and environmental impacts of Trichodesmium bloom sample from the Gulf of Mannar region. HighlightsTrichodesmium is a key primary producer that contributes to global nitrogen balance.This is the first report showing toxins from Trichodesmium bloom from Indian waters.The extracts of Trichodesmium sp. MBDU 524 showed 100% toxicity against A. salina.