Nambali Valsalan Vinithkumar

Evaluation of significant sources influencing the variation of physico-chemical parameters in Port Blair Bay, South Andaman, India by using multivariate statistics.

Port Blair is the capital city of Andaman & Nicobar Islands, the union territory of India. More than 50% of the population of these islands lives around Port Blair Bay. Therefore the anthropogenic effects in the bay water were studied for monitoring purpose from seven stations. Physico-chemical parameters of seawater were analyzed in samples collected once in every 3 months for 2 years from seven sampling stations located in Port Blair Bay, South Andaman Island to evaluate the spatial and tidal variation. Cluster analysis and factor analysis were applied to the experimental data in an attempt to understand the sources of variation of physico-chemical parameters. In cluster analysis, the stations Junglighat Bay and Phoenix Bay having high anthropogenic influence formed a separate group. The factors obtained from factor analysis indicated that the parameters responsible for physico-chemical variations are mainly related to land run-off, sewage outfall and tidal flow.

Multivariate statistical approach to identify significant sources influencing the physico-chemical variables in Aerial Bay, North Andaman, India.

Aerial Bay is one of the harbor towns of Andaman and Nicobar Islands, the union territory of India. Nevertheless, it is least studied marine environment, particularly for physico-chemical assessment. Therefore, to evaluate the annual spatiotemporal variations of physico-chemical parameters, seawater samples collected from 20 sampling stations covering three seasons were analyzed. Multivariate statistics is applied to the investigated data in an attempt to understand the causes of variation in physico-chemical parameters. Cluster analysis distinguished mangrove and open sea stations from other areas by considering distinctive physico-chemical characteristics. Factor analysis revealed 79.5% of total variance in physico-chemical parameters. Strong loading included transparency, TSS, DO, BOD, salinity, nitrate, nitrite, inorganic phosphate, total phosphorus and silicate. In addition, box-whisker plots and Geographical Information System based land use data further facilitated and supported multivariate results.

l -Asparaginase from Streptomyces griseus NIOT-VKMA29: optimization of process variables using factorial designs and molecular characterization of l -asparaginase gene

Marine actinobacteria are known to be a rich source for novel metabolites with diverse biological activities. In this study, a potential extracellular L-asparaginase was characterised from the Streptomyces griseus NIOT-VKMA29. Box-Behnken based optimization was used to determine the culture medium components to enhance the L-asparaginase production. pH, starch, yeast extract and L-asparagine has a direct correlation for enzyme production with a maximum yield of 56.78 IU mL−1. A verification experiment was performed to validate the experiment and more than 99% validity was established. L-Asparaginase biosynthesis gene (ansA) from Streptomyces griseus NIOT-VKMA29 was heterologously expressed in Escherichia coli M15 and the enzyme production was increased threefold (123 IU mL−1) over the native strain. The ansA gene sequences reported in this study encloses several base substitutions with that of reported sequences in GenBank, resulting in altered amino acid sequences of the translated protein.

Comparative Investigation of Water Quality Parameters of Aerial & Rangat Bay, Andaman Islands Using In-Situ Measurements and Spatial Modelling Techniques

Aerial Bay and Rangat Bay witness extensive and diverse activities such as tourism, shipping and fisheries. These activities along with domestic discharge may significantly affect the seawater quality in the bays. Therefore seawater samples were analyzed to comprehend the physicochemical and biological variables and its sources that affected the seawater quality at both the bays. The land-use/land cover data was studied to understand the source of pollution and to classify the areas into various categories relating to prevailing environment adjoining these bays. Difference between sites and the variables responsible for variation were analyzed using one-way analysis of variance (ANOVA). Pearson correlation was used to find the relationship between variables and degree of dependency towards the other. Agglomerative hierarchical cluster analysis grouped the sampled sites, which helped to identify the similarity/dissimilarity within and between sites at both high and low tides. Moreover, inverse distance weighted interpolation technique was used to develop comparative potential mapping using Arc GIS software (ver. 9.3.1), generated a model for spatial changes at both sites. The results indicate the increase of pollution level at Aerial Bay due to anthropogenic activities, whereas Rangat Bay showed less variance due to frequent open sea water exchange. The combination of both statistical and GIS modeling techniques have proven to be excellent methods for spatial analysis and integration of these data to derive useful outputs and visual modeling.

Changes in verte brate‐type steroids and 5‐hydroxytryptamine during ovarian recrudescence in the Indian spiny lobster, Panulirus homarus

Abstract Vertebrate‐type steroids (estradiol‐17β and progesterone) and 5‐hydroxytryptamine (5‐HT) were examined during the different stages of ovarian maturation in the Indian spiny lobster Panulirus homarus. Estradiol‐17β and progesterone in the haemolymph and ovary were quantified by radioim‐munoassay. Estradiol‐17β was not detectable in the haemolymph when the oocytes were in stage I. It appeared in the haemolymph only as the oocytes attained stage II. Subsequently, a sharp increase in the level of estradiol‐17β was observed in the haemolymph of lobsters with stage III oocytes; it then showed a significant fall when the ovary was full of stage IV oocytes. Although progesterone was also not detectable in the haemolymph when the oocytes were in stage I, it gradually increased during stages II and III and reached a peak level during stage IV. Surprisingly, both estradiol‐17β and progesterone were detectable in the ovary from stage I onwards. In the ovary, estradiol‐17β and progesterone showed peak levels during stages III and IV, respectively. A stage‐dependent change in the activity and distribution of 5‐hydroxytryptaminergic neurons in the brain and thoracic ganglia was also observed immunocytochemically in relation to ovarian recrudescence. Furthermore, HPLC‐EC conducted on the level of 5‐HT in the brain and thoracic ganglia indicated similar changes in relation to ovarian maturation. These results strongly suggest that 5‐HT is involved in ovarian development through certain inhibitory/stimulatory factors present in the X‐organ‐sinus gland complex of the eye‐stalk in the spiny lobster P. homarus.

Heterologous expression, purification, and phylogenetic analysis of oil-degrading biosurfactant biosynthesis genes from the marine sponge-associated Bacillus licheniformis NIOT-06

Surfactin is a lipopeptide, composed of one β-hydroxy fatty acid, a long fatty acid moiety, and seven amino acids. In this study, the biosurfactant biosynthesis genes; 4′-pantetheinyl transferase (sfp), phosphopantetheinyl transferase (sfpO), and surfactin synthetase (srfA) have been characterized from the marine sponge-associated Bacillus licheniformis NIOT-06 from the Andaman and Nicobar Islands. The purified recombinant biosurfactant revealed excellent emulsification activity with crude oil and kerosene. Reverse-phase high-performance liquid chromatography resolved the purified recombinant biosurfactant into several fractions and one of which had significant surface tension reducing property. Fourier transform infrared spectroscopy spectrum also revealed the presence of C–N–N, alkenes, and N–H as the functional groups, and a similar overlapping pattern was observed with that of standard lipopeptide surfactin. The diversity and phylogeny of sfp, sfpO, and srfA gene sequences were compared with other eubacteria. The sfp, sfpO, and srfA gene sequences obtained from Bacillus licheniformis NIOT-06 were diverse and appeared to be partially conserved when compared with the GenBank reported sequences of several eubacteria.

Molecular expression of l-asparaginase gene from Nocardiopsis alba NIOT-VKMA08 in Escherichia coli: A prospective recombinant enzyme for leukaemia chemotherapy

l-Asparaginase is an antineoplastic agent that selectively reduces the level of l-asparagine in blood and diminishes the proliferation of cancerous cells. Studies were carried out on the cloning and heterologous expression of l-asparaginase biosynthesis gene (ansA) from Nocardiopsis alba NIOT-VKMA08 to achieve the stable inducible system that overproduces the glutaminase-free recombinant l-asparaginase. Overexpression of recombinant l-asparaginase was achieved with an optimized final concentration of 1.5mM of isopropyl-β-d-thiogalactoside (IPTG) and the enzyme was expressed as a soluble protein. The recombinant enzyme was purified using nickel-nitrilotriacetic acid (Ni-NTA) chromatography and the purified enzyme disclosed an elevated level of asparaginase activity (158.1IU/mL). Optimum pH and temperature of the purified l-asparaginase for the hydrolysis of l-asparagine were 8.0 and 37°C and it was very specific for its natural substrate, l-asparagine. Detailed studies were carried out on the kinetics of enzyme reaction, catalytic activity, temperature and ionic strength and the thermostability of the l-asparaginase enzyme. The functional characterisation of the recombinant l-asparaginase was studied through Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), in silico sequence analysis and protein structural modelling. Glutaminase activity was not detected in the recombinant l-asparaginase, which could reduce the probable side effects during leukaemia therapy.

Multivariate and geo-spatial approach for seawater quality of Chidiyatappu Bay, south Andaman Islands, India

Chidiyatappu Bay is one of the least disturbed marine environments of Andaman & Nicobar Islands, the union territory of India. Oceanic flushing from southeast and northwest direction is prevalent in this bay. Further, anthropogenic activity is minimal in the adjoining environment. Considering the pristine nature of this bay, seawater samples collected from 12 sampling stations covering three seasons were analyzed. Principal Component Analysis (PCA) revealed 69.9% of total variance and exhibited strong factor loading for nitrite, chlorophyll a and phaeophytin. In addition, analysis of variance (ANOVA-one way), regression analysis, box-whisker plots and Geographical Information System based hot spot analysis further simplified and supported multivariate results. The results obtained are important to establish reference conditions for comparative study with other similar ecosystems in the region.

Enterococcus species diversity and molecular characterization of biomarker genes in Enterococcus faecalis in Port Blair Bay, Andaman and Nicobar Islands, India.

This study was performed to evaluate the abundance and diversity of Enterococcus sp. and the distribution of biomarker genes in Enterococcus faecalis in Port Blair Bay, Andaman and Nicobar Islands. The Enterococcus sp. densities at the seven sampling stations were highly influenced by tidal fluctuations and season. The distributions and diversities of species varied in the inner and outer regions of Port Blair Bay. Among the 1816 total isolates, the occurrence of fecal Enterococcus was high (1.78×10(4) CFU/100 mL) in Phoenix Bay. Moreover, 67.76% of the isolates were identified as Enterococcus, and the most frequently identified species were E. hirae, E. avium and E. faecalis. Assessments of antibiotic resistance and biomarker genes revealed the maximum occurrence in the Aberdeen Bay isolates. The most prevalent biomarker genes observed in the E. faecalis isolates were gelE and asa1, whereas cyl was not found among the isolates. In silico sequence analysis of biomarker genes of E. faecalis also revealed that they are evolutionarily well conserved with those of earlier reports. Further, multivariate analysis distinguished the JB, PB and OS stations from the other stations according to distinctive microbial densities and compositions. In addition, the Shannon-Wiener diversity indices and box-whisker plots further facilitated and supported the multivariate results.

On the Recurrence of Coral Bleaching and Recovery in North Bay, Port Blair, Andaman and Nicobar Islands

Coral cover, live-form categories, bleaching and their recovery were monitored in North Bay, South Andaman during pre- and post-tsunami periods. The reef is a fringing type, with a total coral cover of 313,382 m2. The total live and dead coral percentages recorded prior to tsunami were 29.4% and 27%, respectively. A patchy bleaching of 7.5% was recorded in month of April–May 2005. However, the coral reef started to recover quickly, and as much as 4.7% of recovery was recorded, and 2.8% of the bleached coral failed to recover. No significant variations in the physicochemical parameters were recorded prior to and post-tsunami. A sudden change in the water column height due the land subduction caused by the mega earthquake on 26 December 2004 was evident. The sudden change in depth and light penetration might have exerted a stress in the corals, leading to expulsion of zooxanthellae from the gastrodermal layer of cells, causing the bleaching phenomena.