Phenazine-1-carboxamide (PCN) from Pseudomonas sp. strain PUP6 selectively induced apoptosis in lung (A549) and breast (MDA MB-231) cancer cells by inhibition of antiapoptotic Bcl-2 family proteins.

Phenazine-1-carboxamide (PCN), a naturally occurring simple phenazine derivative isolated from Pseudomonas sp. strain PUP6, exhibited selective cytotoxic activity against lung (A549) and breast (MDA-MB-231) cancer cell lines in differential and dose-dependent manner compared to normal peripheral blood mononuclear cells. PCN-treated cancer cells showed the induction of apoptosis as evidenced by the release of low level of LDH, morphological characteristics, production of reactive oxygen species, loss of mitochondrial membrane potential (ΔΨm) and induction of caspase-3. At molecular level, PCN instigates apoptosis by mitochondrial intrinsic apoptotic pathway via the overexpression of p53, Bax, cytochrome C release and activation of caspase-3 with the inhibition of oncogenic anti-apoptotic proteins such as PARP and Bcl-2 family proteins (Bcl-2, Bcl-w and Bcl-xL). The in silico docking studies of PCN targeted against the anti-apoptotic members of Bcl-2 family proteins revealed the interaction of PCN with the BH3 domain, which might lead to the induction of apoptosis due to the inhibition of antiapoptotic proteins. Due to its innate inhibition potential of antiapoptotic Bcl-2 family proteins, PCN may be used as potent anticancer agent against both lung and breast cancer.

5-Methyl phenazine-1-carboxylic acid: a novel bioactive metabolite by a rhizosphere soil bacterium that exhibits potent antimicrobial and anticancer activities.

A new rhizosphere soil bacterium that exhibits antimicrobial potential against human pathogens was isolated. On the basis of 16S ribosomal RNA nucleotide sequence homology and subsequent phylogenetic tree analysis, the strain PUW5 was identified as Pseudomonas putida. A bioactive metabolite was extracted and purified using silica gel column chromatography and preparative HPLC. Characterization of metabolite was done by employing Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and mass spectroscopy (MS). On the basis of spectroscopic data, the metabolite was structurally elucidated as 5-methyl phenazine-1-carboxylic acid betaine (MPCAB). The MPCAB exhibits selective cytotoxicity towards lung (A549) and breast (MDA MB-231) cancer cell lines in dose-dependent manner with IC50 value of 488.7±2.52 nM and 458.6±2.48 nM respectively. The MPCAB exhibited inhibition of cell viability, DNA synthesis, induced G1 cell cycle arrest and apoptosis in cancer cells. The docking and interaction studies confirmed the binding potential of MPCAB with Bcl-2 than Bcl-xL and Bcl-w proteins. These results strongly suggest that the MPCAB induces apoptosis in A549 and MDA MB-231 cancer cells through mitochondrial intrinsic pathway via activation of caspase-3 and down regulation of Bcl-2 protein.

Characterization of chryseobacterium aquaticum strain PUPC1 producing a novel antifungal protease from rice rhizosphere soil.

Strain PUPC1 produces an antifungal protease as well as plant growth promoting enzymes such as 1- aminocyclopropane-1-carboxylate (ACC) deaminase and phosphatase. Morphological, cultural, and physiological characteristics as well as 16S rRNA gene-sequence-based phylogenetic analysis confirmed the taxonomic affiliation of PUPC1 as Chryseobacterium aquaticum. The optimum growth of PUPC1 was observed at pH 6.0 and 30 degrees , and maximum protease production was observed in medium B amended with 1% tryptone, 0.5% sucrose, and 0.005% MnCl2. The protease was purified by ammonium sulfate precipitation, Sephadex G-75 gel filtration chromatography, and electroelution from preparative SDS-PAGE. The protease had a molecular mass of 18.5 kDa. The optimum pH and temperature stability of the protease were pH 5.0- 10.0 and temperature 40-70 degrees . Chryseobacterium aquaticum PUPC1 and its protease showed a broad-spectrum antifungal activity against phytopathogenic fungi. Strain PUPC1 also exhibited plant growth promoting traits. The objective of the present investigation was to isolate a strain for agricultural application for plant growth promotion and biocontrol of fungal diseases.

Functional characterization of antagonistic fluorescent pseudomonads associated with rhizospheric soil of rice (Oryza sativa L.).

Antagonistic fluorescent pseudomonads isolated from rhizospheric soil of rice were characterized by 16S rRNA amplicon and fatty acid methyl ester (FAME) analyses. Antagonistic isolates were grown in the fermentation media, and production of antibiotics was confirmed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Production of fungal cell-wall-degrading enzymes such as protease, cellulase, pectinase, and chitinase was determined. Dendrogram based on the major and differentiating fatty acids resulted into 5 clusters, viz., cluster I (P. pseudoalcaligenes group), cluster II (P. plecoglossicida group), cluster III (P. fluorescens group), cluster IV (P. aeruginosa group), and cluster V (P. putida group). Characteristic presence of high relative proportions of cyclopropane (17:0 CYCLO w7c) was observed in antagonistic bacteria. Data revealed biodiversity among antagonistic fluorescent pseudomonads associated with the rice rhizosphere. Results presented in this study will help to identify the antagonistic isolates and to determine their mechanisms that mediate antagonism against fungal pathogens of rice.