Muneer Ahmed Qazi

Yeast Extract as the Most Preferable Substrate for Optimized Biosurfactant Production by rhlB Gene Positive Pseudomonas putida SOL-10 Isolate

Oil contaminated sites are enriched source of microorganisms that produce a variety of surface active amphiphilic compounds known as biosurfactants. Pseudomonas putida SOL-10 strain isolated from oil contaminated soil of Fimkassar oil field, Chakwal, Pakistan, was identified by standard morphological, biochemical and 16S rRNA sequence analysis methods. SOL-10 strain was initially screened for biosurfactant production using oil spreading test and then manifestation of rhlB (rhamnolipid) gene was confirmed by PCR using gene-specific primers. Maximum biosurfactant production in terms of surface tension (29.9 mN m-1) and emulsification index (E24, 73.45%), was achieved when the strain was grown in MSM supplemented with yeast extract (1.5-2 %, w/v) and urea (0.1 %, w/v) as carbon and nitrogen sources, respectively, and the physical parameters were adjusted at pH 7.0, temperature 30°C, 150 rpm agitation speed. The biosurfactant emulsified various hydrocarbons tested, being more effective against xylene and kerosene (85.19% and 70.59%, respectively). The crude biosurfactant also showed stability at a wide range of temperature (25-80°C), pH (1-9) and salt concentration (1-5%, w/v). The stability and hydrocarbon emulsifying potential of the biosurfactant indicated its possible use as decent contender for future environmental applications like biodegradation and bioremediation of organic pollutants.

Isolation and characterization of a biosurfactant-producing Fusarium sp. BS-8 from oil contaminated soil

This study reports characterization of a biosurfactant‐producing fungal isolate from oil contaminated soil of Missa Keswal oil field, Pakistan. It was identified as Fusarium sp. BS‐8 on the basis of macroscopic and microscopic morphology, and 18S rDNA gene sequence homology. The biosurfactant‐producing capability of the fungal isolates was screened using oil displacement activity, emulsification index assay, and surface tension (SFT) measurement. The optimization of operational parameters and culture conditions resulted in maximum biosurfactant production using 9% (v/v) inoculum at 30°C, pH 7.0, using sucrose and yeast extract, as carbon and nitrogen sources, respectively. A C:N ratio of 0.9:0.1 (w/w) was found to be optimum for growth and biosurfactant production. At optimal conditions, it attained lowest SFT (i.e., 32 mN m−1) with a critical micelle concentration of ≥ 1.2 mg mL−1. During 5 L shake flask fermentation experiments, the biosurfactant productivity was 1.21 g L−1 pure biosurfactant having significant emulsifying index (E24, 70%) and oil‐displacing activity (16 mm). Thin layer chromatography and Fourier transform infrared spectrometric analyses indicated a lipopeptide type of the biosurfactant. The Fusarium sp. BS‐8 has substantial potential of biosurfactant production, yet it needs to be fully characterized with possibility of relatively new class of biosurfactants.

Endophytic fungi associated with Taxus fuana (West Himalayan Yew) of Pakistan: potential bio-resources for cancer chemopreventive agents.

Abstract Context: Endophytic fungi, being a prolific source of bioactive secondary metabolites, are of great interest for natural product discovery. Objective: Isolation and partial characterization of endophytic fungi inhabiting the leaves and woody parts of Taxus fuana Nan Li & R.R. Mill. (Taxaceae) and evaluation of biological activity. Materials and methods: Endophytic fungal isolates were identified by molecular analysis of internal transcribed spacer (ITS) regions of 18S rDNA. Extracts of the endophytic fungi cultured on potato dextrose agar and modified medium were evaluated using cancer chemoprevention bioassays [inhibition of TNF-α-induced NFκB, aromatase and inducible nitric oxide synthase (iNOS); induction of quinone reductase 1 (QR1)] and growth inhibition with MCF-7 cells. Results: Nine of 15 fungal isolates were identified as belonging to Epicoccum, Mucor, Penicillium, Chaetomium, Paraconiothriym, Plectania or Trichoderma. Five of the 15 extracts inhibited NFκB activity (IC50 values ranging between 0.18 and 17 μg/mL) and five inhibited iNOS (IC50 values ranging between 0.32 and 12.9 μg/mL). In the aromatase assay, only two isolates mediated inhibition (IC50 values 12.2 and 10.5 μg/mL). With QR1 induction, three extracts exhibited significant activity (concentrations to double activity values ranging between 0.20 and 5.5 μg/mL), and five extracts inhibited the growth of MCF-7 cells (IC50 values ranging from 0.56 to 17.5 μg/mL). Six active cultures were derived from woody parts of the plant material. Conclusion: The endophytic fungi studied are capable of producing pharmacologically active natural compounds. In particular, isolates derived from the wood of Taxus fuana should be prioritized for the isolation and characterization of bioactive constituents.

Biological Evaluation of Endophytic Fungus Chaetomium sp. NF15 of Justicia adhatoda L.: A Potential Candidate for Drug Discovery.

Background The endophytes of medicinal plants, such as Justicia adhatoda L., represent a promising and largely underexplored domain that is considered as a repository of biologically active compounds. Objectives The aim of present study was isolation, identification, and biological evaluation of endophytic fungi associated with the J. adhatoda L. plant for the production of antimicrobial, antioxidant, and cytotoxic compounds Materials and Methods Endophytic fungi associated with the J. adhatoda L. plant were isolated from healthy plant parts and taxonomically characterized through morphological, microscopic, and 18S rDNA sequencing methods. The screening for bioactive metabolite production was achieved using ethyl acetate extracts, followed by the optimization of different parameters for maximum production of bioactive metabolites. Crude and partially purified extracts were used to determine the antimicrobial, antioxidant, and cytotoxic potential Results Out of six endophytic fungal isolates, Chaetomium sp. NF15 showed the most promising biological activity and was selected for detailed study. The crude ethyl acetate extract of NF15 isolate after cultivation under optimized culture conditions showed promising antimicrobial activity, with significant inhibition of the clinical isolates of Staphylococcus aureus (87%, n=42), Pseudomonas aeruginosa (> 85%, n = 41), and Candida albicans (62%, n = 24). Conclusions The present study confirms the notion of selecting endophytic fungi of medicinal plant Justicia for the bioassay-guided isolation of its bioactive compounds, and demonstrates that endophytic fungus Chaetomium sp. NF15 could be a potential source of bioactive metabolites