S. Jayachandran

Induction of apoptosis and cell cycle arrest by Bis (2-ethylhexyl) phthalate produced by marine Bacillus pumilus MB 40

Marine microorganisms represent a potential source for the production of biomedically useful compounds active against inflammation, cancer, diabetes, etc. Marine Bacillus pumilus MB 40 (GenBank accession no. HQ705771) isolated from deep sea water column (1000m depth) near Andaman and Nicobar islands produced a bioactive lead, Bis (2-ethylhexyl) phthalate (BEHP) with a molecular formula of C(6)H(4)(CO(2)C(8)H(17))(2) and a molecular ion at m/z 391 (M(+)). Anti proliferative effect of the isolated compound was examined by MTT assay in human erythroleukemic K562 cells and the IC(50) of BEHP was found to be 21μM. BEHP was able to induce apoptosis involving caspases pathway, besides regulating mitochondrial enzymes. Further, western blot analysis revealed the activation of caspases family proteins viz., caspase 8, caspase-9 and caspase-3. An increase in the expression of Bax mRNA concomitant with a decrease in mRNA of Bcl-2 in BEHP treated K562 cells was also observed. AO/EB staining of BEHP treated K562 cells further confirmed the progression of apoptosis as evidenced by morphological changes including nuclear condensation, cell shrinkage, and formation of apoptotic bodies. Treatment of K562 cells with BEHP induced the progressive accumulation of fragmented DNA in a time dependent manner. This pattern appeared as a typical laddering distribution of DNA fragmentation due to intranucleosomal cleavage associated with apoptosis. Based on flow cytometric analysis it has become evident that the compound was also effective in arresting the cell cycle at a sub G0/G1 phase.

Physicochemical analyses of the exopolysaccharides produced by a marine biofouling bacterium, Vibrio alginolyticus

Abstract Growth and exopolysaccharide (EPS) production by Vibrio alginolyticus , a marine fouling bacterium was studied in sea water nutrient broth in vitro. Fourier transformed infrared spectral analysis of the purified EPS revealed prominent characteristic groups corresponding to polyhydric alcohols. When the derivatized alditol acetates from EPS were separated by gas chromatography five peaks corresponding to glucose tetraacetate, xylopyranose tetraacetate, aminoarabinose tetraacetate, aminoribose tetraacetate and glucose pentaacetate, were observed. Mass spectrophotometric analysis of derivatized EPS revealed the presence of glucose, aminoarabinose, aminoribose and xylose in the molar ratio of 2:1:9:1. Viscometric studies suggested that the molecular weight of EPS was ∼6.39×10 6 Da. Rheological studies of aqueous EPS showed good shearing property. However, the EPS was unstable at high temperatures and high pH.

Biofilm formation by Pseudoalteromonas ruthenica and its removal by chlorine

Abstract The distribution of a recently described marine bacterium, SBT 033 GenBank Accession No. AY723742), Pseudoalteromonas ruthenica, at the seawater intake point, outfall and mixing point of an atomic power plant is described, and its ability to form biofilm was investigated. The effectiveness of the antifouling biocide chlorine in the inactivation of planktonic as well as biofilm cells of P. ruthenica was studied in the laboratory. The results show that the planktonic cells were more readily inactivated than the cells enclosed in a biofilm matrix. Viable counting showed that P. ruthenica cells in biofilms were up to 10 times more resistant to chlorine than those in liquid suspension. Using confocal laser scanning microscopy it was shown that significant detachment of P. ruthenica biofilm developed on a glass substratum could be accomplished by treatment with a dose of 1 mg l−1 chlorine. Chlorine-induced detachment led to a significant reduction in biofilm thickness (up to 69%) and substratum coverage (up to 61%), after 5-min contact time. The results show that P. ruthenica has a remarkable ability to form biofilms but chlorine, a common biocide, can be used to effectively kill and detach these biofilms.

Identification of a Novel Antifungal Peptide with Chitin-Binding Property from Marine Metagenome

A novel antifungal peptide with 36 amino acids was identified by functional screening of a marine metagenomic library. The peptide did not show similarity with any existing antimicrobial peptide sequences in the databank. The108 bp ORF designated as mmgp1 was cloned and expressed in Escherichia coli BL21 (DE3) using pET expression system. Mass spectrometry analysis of the purified recombinant peptide revealed a molecular mass of 5026.9 Da. The purified recombinant peptide inhibited the growth of Candida albicans and Aspergillus niger. The peptide was predicted to adopt α- helical conformation with an extended coil containing a ligand binding site for N-acetyl-D-glucosamine. The α- helicity of the peptide was demonstrated by circular dichroism spectroscopy in the presence of chitin or membrane mimicking solvent, trifluoroethanol. The chitin binding property of the peptide was also confirmed by fast performance liquid chromatography.

Direct cell penetration of the antifungal peptide, MMGP1, in Candida albicans

An antifungal peptide, MMGP1, was recently identified from marine metagenome. The mechanism of cellular internalization of this peptide in Candida albicans was studied using fluorescein 5–isothiocynate (Sigma, California, USA) labeling followed by fluorescence microscopy and flow cytometry analyses. The peptide could enter C. albicans cells even at 4 °C, where all energy‐dependent transport mechanisms are blocked. In addition, the peptide internalization was not affected by the endocytic inhibitor, sodium azide. The kinetic study has shown that the peptide was initially localized on cell membrane and subsequently internalized into cytosol. The MMGP1 treatment exhibited time‐dependent cytotoxicity in C. albicans as evidenced by SYTOX Green (Molecular Probes Inc., Eugene, Oreg) uptake. Copyright

Antibody specific to 43 kDa excretory-secretory antigenic peptide of Taenia solium metacestode as a potential diagnostic marker in human neurocysticercosis.

Recent studies suggest excretory-secretory (ES) antigen specific antibody detection tests to be of promising utility in laboratory diagnosis of many parasitic diseases in human including neurocysticercosis (NCC). The objective of the present study was to characterize the ES antigens collected from in vitro culture of Taenia solium metacestode larvae, and to identify specific ES peptides as diagnostic markers. Three ES peptides viz., 67kDa, 43kDa and 32kDa, were found to be diagnostic for NCC based on high sensitivity and specificity of their reactivity to either serum or cerebrospinal fluid (CSF) specimens. More remarkably, the 43kDa ES peptide was found reactive with CSF and serum specimens from confirmed NCC patients with absolute specificity and a high sensitivity (88.23% in serum and 89.28% in CSF). This peptide was also detected by sera and CSF from clinically suspected NCC patients but with a decreased sensitivity correlating with the decreasing order of the certainty of diagnosis as per a criteria proposed earlier. The 43kDa ES peptide is suggested to be an important peptide of diagnostic utility in NCC.

Recombinant Gluconacetobacter diazotrophicus Containing Cry1Ac Gene Codes for 130-kDa Toxin Protein

Recombinant Gluconacetobacter diazotrophicus containing Cry1Ac gene from Bacillus thuringiensis var. kurstaki borne on pKT230, shuttle vector, was generated. PCR amplification of Cry1Ac gene present in recombinant G. diazotrophicus yielded a 278-bp DNA product. The nitrogenase assay has revealed that the recombinant G. diazotrophicus in sugarcane stem produced similar levels of nitrogenase compared to wild-type G. diazotrophicus. The presence of 130-kDa protein in apoplastic fluid from sugarcane stem harvested from pots inoculated with recombinant G. diazotrophicus shows that the translocated G. diazotrophicus produces 130-kDa protein which is recognized by the hyperimmune antiserum raised against 130-kDa protein. The first instar Eldana saccharina neonate larvae that fed on artificial medium containing recombinant G. diazotrophicus died within 72 h after incubation.

Production of diamino propionic acid ammonia lyase by a new strain of Salmonella typhimurium PU011.

BackgroundSeeds of the legume plant Lathyrus sativus, which is grown in arid and semi arid tropical regions, contain Diamino Propionic acid (DAP). DAP is a neurotoxin, which, when consumed, causes a disease called Lathyrism. Lathryrism may manifest as Neurolathyrism or Osteolathyrism, in which the nervous system, and bone formation respectively, are affected. DAP ammonia lyase is produced by a few microorganisms such as Salmonella typhi, Salmonella typhimurium and Pseudomonas, and is capable of detoxifying DAP.ResultsS. typhimurium PU011, a non-virulent bacterial strain isolated in our lab, was found to produce DAP ammonia lyase enzyme when grown in minimal medium containing DAP. There was a direct correlation between biomass yield and enzyme activity, until 16 h post inoculation in minimal medium containing DAP. Following ammonium sulphate precipitation and passing through Sephadex G100, CM-Sephadex and DEAE-Sephacel for crude enzyme extract preparation, about 68-fold enzyme purity was obtained. The purified enzyme gave maximum activity at pH 8.0 and was stable up to 45 degrees C. The Km value for the substrate was found to be 0.685mM, calculated from a Line Weaver Burk plot.ConclusionA new bacterial strain, S.typhimurium PU 011, which is capable of producing DAP ammonia lyase, was isolated.

Inhibitory effects of bioactive leads isolated from Pseudomonas aeruginosa PS3 and Pseudomonas fluorescens PS7 on MAP kinases and down regulation of pro inflammatory cytokines (TNF-α, IL-1β) and mediators (NO, iNOS and COX).

Pure lead molecules, showing anti-inflammatory effect were isolated from the marine Pseudomonas aeruginosa PS3 (GenBank Accession No. EF488968) and Pseudomonas fluorescens PS7 (GenBank Accession No. EF488969) using solvent extraction procedures, subsequent column fractionation, followed by bio activity based screening. The structures of the lead molecules (3S, 8aS)-3-isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione (Compound 1) and (8aS)-3-(4-hydroxybenyl) hexahydropyrrolo[1,2-a]pyrazine-1,4-dione (Compound 2) obtained from P. aeruginosa PS3 and P. fluorescens PS7 respectively were established employing spectral analysis. Compounds 1 and 2 at their IC(50) values of 84 and 53μM concentrations respectively down regulated expression of tumor necrosis factor-α (TNF-α) and interleukin 1-β (IL-1β) in peripheral blood mononuclear cells (PBMCs) and inducible nitric oxide synthase (iNOS) gene in RAW 264.7 cells. Immunoblot analysis revealed the inhibitory effect of pure compounds on phosphorylation of all the three mitogen activated protein kinases (MAPK) such as ERK, JNK and p38 MAPK. The results of the present investigation revealed that the pure compounds are anti-inflammatory in nature.

Cloning, expression, and sequence analysis of diaminopropionate ammonia lyase gene from a nonvirulentsalmonella typhimurium PU011

AbstractBackground: Seeds ofLathyrus sativus, a legume plant, contain 3-oxalyl and 2,3-dioxalyl DAP (O-DAP), neurotoxins which when consumed causes Neurolathyrism or Osteolathyrism, in humans, affecting nervous system and bone formation respectively. Some microorganisms viz virulent and non-virulentSalmonella typhimurium, Salmonella typhi and Pseudomonad have been shown to detoxifyL-α,β-diaminopropionate (DAP), the immediate precursor of O-DAP. Result: The gene coding for diaminopropionate ammonia lyase (DAPAL) which detoxifies DAP was cloned from nonvirulentS. typhimurium PU011 intoEscherichia coli DH5α and the nucleotides sequenced (1212 bp). Whereas the specific enzyme activity of DAPAL obtained from recombinantE. coli PU018 was 0.346 U/mg, the specific activity of the enzyme from nonvirulentS. typhimurium PU011 was 0.351 U/mg. The DAPAL corresponding to 43 kDa protein was found both in nonvirulentS. typhimurium PU011 andE. coli PU018. The Km value was found to be 0.740 mM and 0.680 mM forS. typhimurium PU011 and 0.741 mM and 0.683 mM forE. coli PU018 when grown in minimal medium (MM+DAP) andL. sativus seed extracts respectively, indicating that both of them were capable of utilizing the neurotoxins present inL. sativus seeds. The biomass, enzyme production and the effect of pH and temperature on DAPAL enzyme activity from both non-virulentS. typhimurium PU011 andE. coli PU018 were found to be similar. Conclusion: The recombinantE. coli PU018 as well as non-virulentS. typhimurium PU011 are as good as pathogenicS. typhimurium in detoxifying DAP, the immediate precursor of O-DAP present inL. sativus seeds.