Gopal Dharani

Biodegradation of complex hydrocarbons in spent engine oil by novel bacterial consortium isolated from deep sea sediment.

Complex hydrocarbon and aromatic compounds degrading marine bacterial strains were isolated from deep sea sediment after enrichment on spent engine (SE) oil. Phenotypic characterization and phylogenetic analysis of 16S rRNA gene sequences showed the isolates were related to members of the Pseudoalteromonas sp., Ruegeria sp., Exiguobacterium sp. and Acinetobacter sp. Biodegradation using 1% (v/v) SE oil with individual and mixed strains showed the efficacy of SE oil utilization within a short retention time. The addition of non-ionic surfactant 0.05% (v/v) Tween 80 as emulsifying agent enhanced the solubility of hydrocarbons and renders them more accessible for biodegradation. The degradation of several compounds and the metabolites formed during the microbial oxidation process were confirmed by Fourier transform infrared spectroscopy and Gas chromatography-mass spectrometry analyses. The potential of this consortium to biodegrade SE oil with and without emulsifying agent provides possible application in bioremediation of oil contaminated marine environment.

Farming of spiny lobsters in sea cages in India

Abstract Pueruli and post‐pueruli, early juveniles and sub‐adults of the spiny lobster, Panulirus homarus and juveniles of P. ornatus were grown in different floating sea cages along the southeast coast of India from May 2003 to May 2007. The first type of cage had a galvanised iron pipe frame (2.0 m × 2.0 m × 1.2 m) with steel woven mesh and four inner detachable compartments (0.75 m × 0.75 m × 1.10 m). Fibre‐reinforced plastic was used subsequently to fabricate cages (1 m × 1 m × 1 m). Pueruli and post‐pueruli of P. homarus (1.58 ± 0.62 g SD), stocked at 60 individuals/m2, grew to an average weight of 123.10 ± 26.22 g in 266 days with a survival rate of 70%. Sub‐adults of P. homarus with an average weight (± SD) of 123.61 ± 29.26 g reached 341.25 ± 46.22 g in 225 days at a stocking density of 21 individuals/m2 with a survival of 73 ± 6%. The post‐pueruli grew by 0.46 ± 0.10 g per day with a specific growth rate (SGR) of 1.64, whereas sub‐adults had a growth rate of 0.97 ± 0.20 g per day with a SGR of 0.43. At a higher stocking density of 80 individuals/m2, juveniles (51.83 ± 10.32 g and 58.20 ± 28.22 g) of P. homarus recorded growth rates of 0.86 ± 0.25 (SGR 0.82) and 0.97 ± 0.34 g (SGR 0.96) per day. This study indicates that post‐pueruli of P. homarus can be grown to over 200 g in 12 months and up to 350 g in 16 to 17 months in sea cages. Juveniles (average weight 76.35 ± 34.50 g) of P. ornatus, reared with P. homarus at a stocking density of 80 individuals/m2, recorded a weight gain of 139 g in 155 days at arate of 0.89 ± 0.32 g per day with an SGR of 0.67. Marine live clam, Donax spp., was the main feed supplemented with the gastropod, Xancus pyrum, the green mussel, Perna viridis, marine crab (Charibdis sp.), squid (Loligo sp.), and fish such as clupeids and Leognathus sp. Pueruli and post‐pueruli settled in large numbers (up to 35 individuals/month in one cage) both inside and outside the cages.

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.

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.

Complex bacterial communities in the deep-sea sediments of the Bay of Bengal and volcanic Barren Island in the Andaman Sea.

Deep-sea environments are gaining global attention as potential sources of useful microorganisms, thereby warranting a better understanding of the diversity and genomic potential of the microbes present. To this end, here we provide the first insights into the composition of the bacterial communities in deep-sea sediment samples from the southwestern Bay of Bengal and the geographically distinct volcanic Barren Island in the Andaman Sea. High-throughput 16S rRNA gene sequencing of the sediments revealed the presence of >44,000 operational taxonomic units (OTUs) in each of the samples, suggesting high bacterial diversity. Actinobacteria was the most dominant phylum, representing >20% of the taxonomically assignable OTUs, followed by Firmicutes, Proteobacteria, and Chloroflexi. Numerous bacteria that are potentially involved in the sulfur cycle were observed in the Barren Island sediment sample, while bacteria with clinical and industrial potential were observed in the samples from the southwestern Bay of Bengal. Correlation analysis of the biotic and abiotic parameters showed that the differences in bacterial richness and community composition between the sampling sites were mainly dependent on sediment texture. Using a predictive functional metagenomic approach, this study also discusses the genetic variations that may provide an adaptive advantage to sediment bacterial communities for survival in these extreme deep-sea environments. The results from this study should aid future studies focused on bioprospecting and geochemical cycling in the deep sea.

Biofouling control on ultrafiltration membrane through immobilization of polysaccharide-degrading enzyme: optimization of parameters

AbstractMembrane biofouling remains a significant challenge in the application of ultrafiltration (UF) pretreatment systems in desalination and water industries. Bacterial biofilms produce extracellular polymeric substances, which contain alginate as a major component. There has been an ongoing search to look for passive/non-chemical means of mitigating this problem. We present a method based on immobilization of a polysaccharide-degrading enzyme, alginate lyase (Alg L), onto cellulose acetate membrane to control biofilm formation. Various parameters like Alg L concentration, cross-linker concentration and pH were optimized. Two immobilization procedures were adopted and the Alg L immobilization efficiency of each method was compared. Activation of membrane with a cross-linking agent, followed by Alg L immobilization was found to be relatively more effective. Immobilization was confirmed by determining the activity of the immobilized enzyme; viscosity decrease corresponding to enzymatic degradation of the...

Pseudogracilibacillus marinus sp. nov., isolated from a biofilm formed in coastal seawater.

A Gram-staining-positive, aerobic, motile, rod-shaped (0.4-0.5×2.0-4.0 µm), endospore-forming bacterium, designated strain NIOT.bflm.S4T, was isolated from biofilm formed on high-density polyethylene test coupons in coastal seawater. The strain required seawater for growth. It grew with 1.0-8.0 % (w/v) NaCl, at 4-45 °C and at pH 6.5-9.0, with optimum growth with 4.0-5.0 % (w/v) NaCl, at 30 °C and at pH 7.0-8.0. Phylogenetic analyses based on 16S rRNA and partial dnaK gene sequences showed that strain NIOT.bflm.S4T formed a phylogenetic lineage with Pseudogracilibacillus auburnensis P-207T, the only known species of the genus Pseudogracilibacillusand shared sequence identities of 96.9 and 83 %, respectively, with this strain. The identities of 16S rRNA and partial dnaK gene sequences with members of other related genera such as Gracilibacillus, Paraliobacillus, Ornithinibacillus, Oceanobacillus, Virgibacillus and Lentibacillus were ≤95 and ≤78 %, respectively. The DNA G+C content of strain NIOT.bflm.S4T was 39.1 mol%. MK-7 was found as the sole isoprenoid quinone. The major polar lipids of strain NIOT.bflm.S4T were diphosphatidylglycerol, phosphatidylethanolamine and an unknown lipid. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. Major cellular fatty acids were anteiso-C15 : 0 (27.9 %), anteiso-C17 : 0 (18.6 %), C12 : 0 (8.7 %) and iso-C15 : 0 (6.6 %). On the basis of phenotypic, phylogenetic and chemotaxonomic results, we propose that the isolate represents a novel species of the genus Pseudogracilibacillus, for which the name Pseudogracilibacillus marinus sp. nov. is proposed. The type strain is NIOT.bflm.S4T (=KACC 18456T=MTCC 12376T=TBRC 5831T).

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.

Evaluation of the environmental quality of Parangipettai, Southeast Coast of India, by using multivariate and geospatial tool

The anthropogenic pressure in recent years has driven us to investigate the environmental quality at 22 stations in Parangipettai by collecting seawater samples monthly from 2014 to 2015. The sampling stations were grouped into three different environments, namely, Vellar Estuary (VE), Coleroon Estuary (CE), and Open Sea (OS). Factor analysis showed a total variance of 65.63% and exhibited a strong factor loading for atmospheric temperature (0.914), water temperature (0.917), ammonia (0.767), inorganic phosphate (0.897), total phosphorus (0.783), and phytoplankton (0.829). The index value showed water quality was good in OS (74.18), whereas it was moderate in VE (69.73) and CE (68.47). The visual model developed using Geographical Information System (GIS) displayed a spatial pattern of water temperature and phytoplankton dispersion in a distinct manner. The results obtained through multivariate analysis and GIS-based model are imperative to establish reference for a comparative study with other similar ecosystem for better planning and management of tropical seawaters.

Marine Ecosystems of Andaman and Nicobar Islands – Species Abundance and Distribution

Abstract The marine environment of Andaman and Nicobar Islands is diverse in terms of ecosystems and its biodiversity. The location of Andaman and Nicobar Islands in Bay of Bengal, isolated from surrounding land masses by a long distance, remote for long time evolved into unique, uncontaminated and mostly untouched marine ecosystems. Therefore the endemism in organisms is an inherent property of these islands. The tropical climate with tropical evergreen forest and long rainy seasons influences the water quality of surrounding marine ecosystem which intern define the biodiversity of coastal and offshore water ecosystems. The species abundance and distribution in the marine ecosystems such as mangroves, coral reefs, seaweed beds, seagrass meadows, benthic and offshore pelagic environment are discussed with reference to India and Andaman and Nicobar Islands. Further the major flora and fauna available and their distribution in these islands are also discussed. There are about 6400 marine organisms were reported from Andaman and Nicobar Islands. Eventhough the biodiversity of marine ecosystems of these are studied for many decades, most of the areas are largely unexplored. The abundance and distribution of various species of mangroves, seagrass, seaweed, plankton, invertebrates, fishes, reptiles and mammals in both groups of islands are discussed. Further, the fishery of offshore fishes especially tuna resources are also provided in detail. The biodiversity and distribution is a broad topic and hence major ecosystems and organisms abundance are discussed.