Effectiveness of compost inoculated with phosphate solubilizing bacteria.

AIMS: The present study was carried out to design a phosphate solubilizing bacterial (PSB)-based biofertilizer using locally produced fruit waste. METHOD AND RESULTS: Two PSB strains Pseudomonas aeruginosa CMG4 and AAC1 were inoculated into compost. Six compost piles were prepared with carbon:nitrogen (C:N) ratio 30:1. Four piles were inoculated with PSB and two piles served as a control. After 125 days, composts were considered mature at 29-31°C in the pH range of 7.1-7.3 and 32%-35% moisture content (MC). Accessible calcium (Ca) content increased up to 50 g kg-1 . Microbial analysis showed the survival of P. aeruginosa species in the maturing compost even at higher temperature (~53°C). Native bacterial load was retrieved in the range of 109 -1011 CFUg-1 . Heavy metal concentrations including copper (Cu), lead (Pb), chromium (Cr) and cadmium (Cd) were found to occur below critical thresholds. Seed germination index for compost toxicity was found to be >80%, significantly higher than animal manure and chemical fertilizer, that is, 78% and 31%, respectively, suggesting non-toxicity. CONCLUSIONS: The evaluation of prepared compost by physicochemical parameters revealed that inoculation of P. aeruginosa does not affect the temperature, MC, carbon to nitrogen ratio, organic matter and Mg content but significantly increased the accessible Ca content, suggesting the solubilization of inorganic Ca bound phosphate. Compost was safe in terms of heavy metal concentration and seed germination. SIGNIFICANCE AND IMPACT OF STUDY: This study encourages that the PSB-rich tailored compost can be utilized as a phosphatic biofertilizer to fulfil the demand for phosphorus which would improve and sustain soil fertility.

Utilization of agro waste pectin for the production of industrially important polygalacturonase.

In the present study, a variety of agro-industrial wastes have been utilized for meaningful purpose to produce valuable biocatalyst. All wastes used were low cost and easily accessible while, some available throughout the year. A number of bacterial strains isolated from rotten fruits and vegetables were screened for the production of industrially important polygalacturonase (PGase) using pectin present in these agro-industrial wastes. The strain producing maximum PGase was identified as Bacillus licheniformis KIBE-IB3 on the basis of taxonomic studies and 16S rDNA analysis. Among different agro-industrial wastes studied, high yield of PGase was achieved from fermentation broth having wheat bran (1.0%) as a substrate in to the medium supplemented with nitrogen sources in combination of NaNO3 and yeast extract while KH2PO4 was selected as suitable micronutrient. After optimizing fermentation parameters it was noticed that Bacillus licheniformis KIBE-IB3 was capable of producing maximum PGase at 37 °C, pH 7.0 and after 48 h of incubation time. From the current research, wheat bran was proven as a cheap and easily available source throughout the year for hyper production of pectinase. The utilization of the waste will also help to minimize the concerned environmental issues.

Isolation and partial characterization of phosphate solubilizing bacteria isolated from soil and marine samples.

In the present study the potential of indigenous bacterial isolates from soil rhizosphere and marine environment to promote plant growth was determined. Eight bacterial strains isolated from soil and marine samples were characterized for the phosphate solubilizing activity. Qualitative and quantitative estimation of phosphate solubilization is done. MIC of antibiotic and heavy metals were checked for these strains. Strains show a diverse pattern of antibiotic and heavy metals resistance.

Antibiotic resistance profile: isolation and characterization of clinical isolates of staphylococci from patients with community-acquired skin infections.

Although most bacterial infections of the skin bear out to be minor in nature, a few such dermatologic entities are major, to the spot of yet being fatal. The mortality rate is usually up to 30% to 50% and depends upon the type of infection, original disease, and resistant type. In this study hundred and five bacterial strains were isolated from skin wounds, burns and acne patients from hospitals at different locations in the cosmopolitan city of Karachi. These bacterial strains were identified by conventional methods. Seventy two percent (72%) of total isolated organisms were found to be Staphylococcus aureus while the remaining thirty three percent (33%) were Staphylococcus epidermidis. The antibiotic resistance of identified organisms was carried out by disc-diffusion method with commercially available disc of five antibiotics having different mode of actions such as cell wall synthesis inhibitors, membrane permeability alternatives and DNA synthesis inhibitors. Staphylococcus aureus show more resistant to these antibiotics as compared to Staphylococcus epidermidis. The most effective antibiotic for Staphylococcus aureus is vancomycin showing 80.5% efficacy, then methicillin with 68.0% efficacy, erythromycin with 55.6% efficacy, novobiocin with 54.1% efficacy and then bacitracin with 25.0% efficacy. The most effective antibiotic for Staphylococcus epidermidis is methicillin showing 84.8% efficacy, then vancomycin with 81.2% efficacy, novobiocin with 63.6% efficacy, erythromycin with 42.4% efficacy and then bacitracin with 27.8% efficacy.