Chippu Shakir

Antimicrobial potential and seasonality of red algae collected from the southwest coast of India tested against shrimp, human and phytopathogens

Fifteen seaweeds belong to 13 families and 6 orders of the rhodophyta were sampled for one year from April 2007 to March 2008 along the southwest coast of India (Indian Ocean). The species were examined forin vitro antimicrobial activity against six pathogenicVibrio strains isolated from moribund tiger shrimp (Penaeus monodon), six type cultures (Microbial Type Culture Collection, MTCC) of prominent shrimpVibrio pathogens, 10 multidrug resistant clinical pathogens, four species ofCandida obtained from pulmonary TB patients and four species of plant pathogenic fungi to evaluate their potency to be used as natural antibiotics in pharmaceutical and agriculture field. Bioactivity was analyzed from crude extract of fresh and dried samples prepared from different polar and nonpolar solvents. Of these, four species of red algae (Asparagopsis taxiformis, Laurencia ceylanica, Laurencia brandenii, Hypnea valentiae) were found to be highly active. Broadest and highest activity was observed in the crude extract ofA. Taxiformis. Among the pathogens tested, shrimp pathogenicVibrios were the most susceptible organisms while phytopathogens were found to be little resistant. In the present study, methanol was found to be the best solvent for extracting antimicrobial metabolites from dried samples rather than fresh. Seasonal variation in the antimicrobial activity was observed with higher level of activity recorded fromA. Taxiformis between December and January. The active principle ofA. Taxiformis was purified in column chromatography, TLC and reverse phase HPLC. The individual HPLC peaks were subsequently tested against a panel of pathogenic microorganisms and the active constituent was identified by GC-MS. The antimicrobial profile ofA. Taxiformis suggested that lipophilic compound which was primarily composed of pyrrole-2-carboxylic acid, pentadecanoic acid and octadecanoic acid might have functional role in the chemical defence against microbial invasion and these compounds could be utilized for the development of medically potential products.

Bioactivity of the red algae Asparagopsis taxiformis collected from the Southwestern coast of India

Entre as diversas variedades de algas vermelhas, Asparogopsis taxiformis constitui uma das que apresentam alta biomassa na costa de Kollam (Sudoeste da India). No presente estudo A. taxiformis foi coletada, seca e reduzida a po, apos o que foi realizada sua extracao e feito o fracionamento usando-se cromatografia por coluna. As fracoes individuais foram avaliadas in vitro em ensaios para testar sua capacidade anti-incrustante, anticianobacteria e toxicidade para peixes e crustaceos. A fracao extraida com eter de petroleo e etil acetato (2:8) apresentou o espectro de bioatividade mais forte e amplo. No ensaio anti-incrustacao efetuado com com o molusco pulmonado Limnea truncatula, a fracao algal ativa produziu 80% de repelencia do pe em 150 mg/l, enquanto que no ensaio anticianobacteria a fracao ativa inibiu 100% do crescimento de Trichodesmium sp., em 320 mg/l. A fracao algal mostrou o efeito mais intenso contra peixes no nivel de 60 mg/l. Em relacao aos crustaceos, a toxicidade da fracao ativa foi avaliada tambem visando encontrar compostos nao toxicos para organismos nao alvo, tais como Penaeus monodon e Macrobrachium rosembergii. Foi visto que a fracao ativa da coluna mostrou menor toxicidade para estas especies. Os componentes quimicos da fracao ativa foram identificados por meio dos sistemas cromatograficos, tais como TLC, fase reversa do HPLC e GC-MS. O perfil geral de atividade aponta que a fracao ativa da coluna para A. taxiformis pode conter metabolitos bioativos sinergicos que podem ser utilizados para o controle de organismos incrustantes, explosao algal e peixes herbiboros/predadores em tanques de aquicultura.

Biological activity of the red alga Laurencia brandenii

Biological activity of the red alga Laurencia brandenii The marine red alga Laurencia brandenii collected from the southwest coast of India (Indian Ocean) was extracted and fractioned using column chromatography. The individual fractions were evaluated in vitro via antimicrobial activity against six species of Microbial Type Culture Collection and three species of clinical human pathogens, antipest activity on Sitophilus oryzae, maggoticidal activity against 2nd instar larvae of Sarcophaga sp. and termiticidal activity against Microtermes obesi. It was found that the fraction eluted using petroleum ether:chloroform (6:4) exhibited broader biological activities. The phyco-constituents of the active fraction were identified by gas chromatography-mass spectrometry (GC-MS) analysis. The GC-MS profile of the active fraction revealed that the main constituent was octadecadienoic acid (49.75%) followed by n-hexadecanoic acid (14.24%), which might have a functional role in the biological activities. The overall activity profile envisages that these bioactive compounds from L. brandenii could be utilized as a renewable natural resource for the development of novel environmental-compatible formulations for the control of human pathogens, pests, termites and maggots.

Effect of Stocking Density on the Survival Rate and Growth Performance in Penaeus monodon

In this study, effect of stocking density and water exchange rate on the survival, growth and apparent feed conversion ratio of Penaeus monodon were evaluated. For that, shrimps were cultured at two different stocking densities such as six and twelve post larvae m− 3 for a period of four months. The experimental ponds were harvested after four months of culture. The results revealed that survival rate of shrimps cultured in low density ponds (LD) was higher (68.4%) whereas a lower rate (51.7%) was observed at high density ponds (HD). In the case of average body weight and length, the shrimps reared at LD experimental ponds were 27.8 g and 18.5 cm respectively. In addition, the average FCR value of shrimps reared at LD ponds was higher (1.8) when compared to the shrimps cultured in HD ponds (2.3). Therefore, stocking density of 6 PL/m 3 is recommend for culturing P. monodon in Kollam coast of India under these experimental conditions.