Indian Council of Agricultural Research


Previously Undescribed Antibacterial Polyketides from Heterotrophic Bacillus amyloliquefaciens Associated with Seaweed Padina gymnospora

A heterotrophic marine bacterium Bacillus amyloliquefaciens isolated from seaweed Padina gymnospora exhibited broad spectra of antibacterial activities against pathogenic bacteria Aeromonas hydrophila, Vibrio harveyi, Vibrio vulnificus, and Vibrio parahaemolyticus. The seaweed-associated B. amyloliquefaciens was recognized to possess functional type I polyketide synthase-1 (pks-1) gene, and was used to isolate four homologous compounds with polyketide frameworks. The compounds were characterized as 11-(15-butyl-13-ethyl-tetrahydro-12-oxo-2H-pyran-13-yl) propyl-2-methylbenzoate (1), 9-(tetrahydro-12-isopropyl-11-oxofuran-10-yl)-ethyl-4-ethoxy-2-hydroxybenzoate (2), 12-(aminomethyl)-11-hydroxyhexanyl-10-phenylpropanoate (3), and 7-(14-hydroxypropan-13-yl)-8-isobutyl-7,8-dihydrobenzo[c]oxepin-1(3H)-one (4) by comprehensive nuclear magnetic resonance and mass spectroscopic experiments. The compounds 1–4 displayed significant antibacterial activities against clinically important pathogens V. parahaemolyticus and V. vulnificus (inhibitory zone diameter of ?15 mm, 100 mcg on disk). The electronic and hydrophobic parameters appeared to hold a conspicuous part in directing the antibacterial properties of the compounds. This study revealed seaweed-associated B. amyloliquefaciens as potential source of antimicrobial polyketides for pharmaceutical applications.


Pharmacological potential of sulfated polygalactopyranosyl-fucopyranan from the brown seaweed Sargassum wightii

A sulfated polygalactopyranosyl-fucopyranan characterized as ?????1)-?-Fucp-(2SO3 ?)-(3?1)-?-Fucp-(2SO3 ?)-(4?1)-?- Galp-(4?1)-?-Galp-(4????? was isolated from the brown seaweed Sargassum wightii and evaluated for pharmacological properties with reference to antioxidant, anti-inflammatory, antidiabetic, and antihypertensive activities using different in vitro models. The sulfated polygalactopyranosyl-fucopyranan displayed potential di(phenyl)-(2,4,6-trinitrophenyl) iminoazanium (DPPH), 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS+) radical scavenging, and Fe2+ ion chelating activities (IC90 ~ 1 mg mL?1). The studied polysaccharide displayed higher anti-inflammatory selectivity towards inducive proinflammatory enzyme cyclooxygenase-2 (COX-2, IC90 1.13 mg mL?1) than constitutive cyclooxygenase-1 (COX-1, IC90 > 1.20 mg mL?1) resulting in greater selectivity index (IC90 COX-2/COX-1, 0.93) than synthetic non-steroidal anti-inflammatory drug aspirin (0.88) and also showed potent lipoxygenase-5 inhibition (LOX-5, IC90 1.02 mg mL?1). The studied polysaccharide displayed significantly higher (P < 0.05) antidiabetic properties compared to the antidiabetic agents acarbose and diprotein-A in terms of ?-amylase (IC90 0.93 mg mL?1), ?-glucosidase (IC90 1.48 mg mL?1), and dipeptidyl peptidase-4 (IC90 0.11 mg mL?1) enzyme inhibition potentials. The sulfated polygalactopyranosyl-fucopyranan also displayed potential antihypertensive activity with reference to angiotensin-converting enzyme-I inhibitory activity (IC90 0.2 mg mL?1). Extensive spectroscopic experiments in conjugation with monosaccharide compositional analysis attributed (1?3)-linked ?-fucopyranose units in the polygalactofucan chain with C-2 sulfation and C-4 substituents as O-acetyl/O-methyl/(1?4)-linked ?-galactopyranose. The previously undescribed sulfated polygalactopyranosyl-fucopyranan could function as a potential pharmacophore lead against inflammation, type 2 diabetics, hypertension and utilization as natural antioxidant.


Length–weight relationships of eight deep-sea fish species collected from the southwest coast of India

Length?weight relationships (LWR) for eight deep?sea fishes belonging to six families collected from the south west coast of India are presented. Specimens were caught by deep?sea shrimp trawls with mesh size 24 mm during 2011 and 2013. The b values ranged from 2.13 to 3.71 and the coefficient of determination (r2) ranged from 0.84 to 0.98. A new standard length maximum was recorded for Neoscopelus microchir. The b values estimated during the present study were compared with the values estimated using models based on Bayesian approach deposited in Fish Base.


Nacre formation by epithelial cell cultures from mantle of the black-lip pearl oyster, Pinctada margaritifera

Mantle tissue from the black-lip pearl oyster, Pinctada margaritifera, was cultured in vitro using sterilized seawater supplemented with 0.1% yeast extract as the culture medium. Granular and agranular epithelial cells, hyalinocytes, and fibroblast-like cells were observed in the initial stages of culture. Epithelial cells later formed pseudopodial cell networks containing clusters of granulated cells, which upon maturation released their colored granules. These granules induced formation of nacre crystal deposits on the bottom of the culture plate. Cultures comprised of only granulated epithelial cells were established through periodic sub-culturing of mantle cells and maintained for over 18 mo in a viable condition. Reverse transcriptase PCR of cultured cells demonstrated gene expression of the shell matrix protein, nacrein. To further evaluate the functional ability of cultured granulated epithelial cells, nuclear shell beads were incubated in culture medium containing these cells to induce nacre formation on the beads. Observation of the bead surface under a stereomicroscope at periodic intervals showed the gradual formation of blackish yellow colored nacre deposits. Examination of the bead surface by scanning electron microscopy and energy dispersive X-ray analysis at periodic intervals revealed a distinct brick and mortar formation characteristic of nacre, comprised of aragonite platelets and matrix proteins. Calcium, carbon, and oxygen were the major elements in all stages examined. Our study shows that mantle epithelial cells in culture retain the ability to secrete nacre and can therefore form the basis for future studies on the biomineralization process and its application in development of sustainable pearl culture.


Occurrence of Diatom – Diazotrophic association in the coastal surface waters of south Andaman, India

The heterocystous cyanobacterium Richelia intracellularis Schmidt 1901 is well known for its capability to fix atmospheric nitrogen (N2) in oligotrophic waters. Symbiotic associations of Richelia intracellularis with the diatoms Rhizosolenia hebetata, Rhizosolenia clevei, Rhizosolenia cylindrus and Hemiaulus membranaceus is reported for the first time from the coastal waters of South Andaman, India. In these the symbiotic associations, variationswere observed in the number of vegetative cells, trichomes, and the shape of the heterocysts. The highest number of trichomes was observed in Rhizosolenia clevei (14) per host. The trichomes consisted of 9–10 vegetative cells and a spherical heterocyst that was orientiated toward one end of the host diatom cell. In Rhizosolenia hebetata, three trichomes of Richelia intracellularis were present, one trichome at one end with 7–8 vegetative cells and two trichomes at the other end. In Rhizosolenia cylindrus, two trichomes of Richelia were observed, with a spherical heterocyst and 5–6 vegetative cells. An association between Hemiaulus membranaceus and Richelia intracellularis was also observed but with less frequency. Trichomes were observed in the centre of the diatom. By using the cell-specific rates, the amount of new N provided by the Diatom-Diazotrophic Associations was estimated. This is the first record of a symbiotic association of Richelia in diatoms from Andaman coastal waters.


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