Population fluctuation and vertical distribution of meiofauna in a tropical mudflat at Mandovi estuary, west coast of India

237-245A study was conducted to observe the meiofaunal community structure and its temporal and spatial fluctuation and a profile of vertical distribution of a mudflat in relation to sediment temperature, grain size, organic carbon and sedimentary chlorophyll a. The sampling was carried out for three seasons viz. Pre-monsoon (summer), monsoon and post-monsoon. The faunal density (no/10 cm2) ranged between 945-2063/10 cm2 and 704-1549/10 cm2 at stations 1 and 2 respectively. The fauna was dominated by nematodes, turbellarians and harpacticoid copepods. The fauna fluctuated seasonally. A vertical zonation in the distribution of fauna was significantly correlated with interstitial water, chlorophyll a and sediment organic carbon. It is suggested that meiofauna in mudflats serve as food for the higher trophic levels

<span style="font-size:14.0pt;line-height: 115%;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language: HI" lang="EN-IN">Chitin degrading bacteria from the prawn <i>Metapenaeus dobsoni </i> M. and their control</span>

77-80<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Studies on isolation and characterisation of chitin degrading bacteria of wild prawns from Goa waters were conducted. Investigations revealed that Vibrios were the major group of bacteria involved. From biochemical tests it was found that the associated bacterial flora were represented by Vibrio angillarum and Vibrio parahaemolyticus. Study on the effect of antibiotics and plant extracts indicated the combination of antibiotics with plant extracts (Ocimum sanctum, Azardirchta indica, Phyllanthus niruri) were found to be more effective indicating the synergestic effect of the plant extract.</span

Food utilization, growth and lactate dehydrogenase activity of the prawn, Metapenaeus dobsoni (Miers) fed with commercial diet

356-360An assessment of commercial diet and its impact on conversion efficiency, growth parameters and an enzyme, lactate dehydrogenase (LDH) activity in the eye was made. The test organisms (Metapenaeus dobsoni) were grown in the laboratory using commercial diet (low protein, high carbohydrate and no lipid). It was observed that the growth rate using this diet was not encouraging and could not transform energy at optimum level resulting into low protein and high carbohydrate levels in the edible tissue of the prawns. LDH activity decreased with the growth of the prawns fed on this diet. Three isozymes of LDH were observed in the eye tissue. No effect of this diet could be noticed on the isozyme patterns, The commercial diet used in the present study showed marked effect on the activity of LDH in the eye but could not influence the isozyme patterns of LDH

Isolation and Characterization of a marine bacterium belonging to the genus <i style="">Alkaligenes </i>capable of the complete mineralization of the dibenzothiophene

391-397Following enrichment on benzoate five bacterial isolates capable of aerobic growth on dibenzothiophene were obtained from sea water collected off the west coast of India near the city of Goa. Sampling location had been previously contaminated with furnace oil spilled from a tanker. Classified as marine bacteria by their requirement for and optimum growth on 3% NaCl, all the isolates were identified by morphological observations and biochemical tests as belonging to the genes Alkaligenes. A single isolates producing intense red pigmented colony when growing on dibenzothiophene was chosen for further studies and designated as Strain JR110. During catabolism of dibenzothiophene intermediates were observed after initial dissolution and complete mineralization was achieved. JR110, independently confirmed as belonging to the genus Alkaligenes by Im Tech, India was deposited in their culture collection as MTCC3317

Biosurfactants production by the quinoline degrading marine bacterium <i>Pseudomonas </i>sp. strain GU 104, and its effect on the metabolism of green mussel <i>Perna viridis </i>L<i>.</i>

202-207Biosurfactants produced by bacteria in marine ecosystems are involved in the degradation of hydrocarbons. In the present study, large-scale production of biosurfactants was demonstrated in a quinoline degrading marine bacterium Pseudomonas sp. strain GU 104. Studies were also carried out in experimental set ups to understand the effect of biosurfactants, along with the metabolites of quinoline, on the physiology of the green mussel Perna viridis. Acetylcholinesterase (AchE), lactate dehydrogenase (LDH), phenoloxidase and a-amylase activities from specific organs were analysed. The findings of the present study indicate that biosurfactant, as well as quinoline intermediates, produced by Pseudomonas sp. strain GU 104 do not have a significant effect on the physiology of Perna viridis</i

Catalytic Mechanism of 5-Chlorohydroxyhydroquinone Dehydrochlorinase from the YCII Superfamily of Largely Unknown Function

TftG, 5-chloro-2-hydroxyhydroquinone (5-CHQ) dehydrochlorinase, is involved in the biodegradation of 2,4,5-trichlorophenoxyacetate by Burkholderia phenoliruptrix AC1100. It belongs to the YCII superfamily, a group of proteins with largely unknown function. In this work, we utilized structural and functional studies, including the apo-form and 2,5-dihydroxybenzoquinone binary complex crystal structures, computational analysis, and site-directed mutagenesis, to determine the dehydrochlorination mechanism. The His-Asp dyad, which initiates catalysis, is strongly conserved in YCII-like proteins. In addition, other catalytically important residues such as Pro-76, which orients the His-Asp catalytic dyad; Arg-17 and Ser-56, which form an oxyanion hole; and Asp-9, which stabilizes the oxyanion hole, are among the most highly conserved residues across the YCII superfamily members. The comprehensive characterization of TftG helps not only for identifying effective mechanisms for chloroaromatic dechlorination but also for understanding the functions of YCII superfamily members, which we propose to be lyases