Fate of nitrogen-fixing bacteria in crude oil contaminated wetland ultisol.

The effect of crude oil on the growth of legumes (Calopogonium muconoides and Centrosema pubescens) and fate of nitrogen-fixing bacteria in wetland ultisol was investigated using standard cultural techniques. The results revealed observable effects of oil on soil physico-chemistry, plant growth and nodulation as well as on densities of heterotrophic, hydrocarbonoclastic and nitrogen fixing bacteria. The effects however varied with different levels (0.5%, 1%, 5%, 10%, 15% and 20%) of pollution. Ammonium and nitrate levels were high in the unpolluted soil but decreased with increase in pollution levels. Nitrite was not detected in contaminated soil probably due to the reduction in numbers of nitrogen fixers, from 5.26 ± 0.23 × l0(6)cfu/g in unpolluted soil to 9.0 ± 0.12 × 10(5) and 2.2 ± 0.08 × l0(5) cfu/g in soils with 5% and 20% levels of pollution respectively. The contaminated soil also exhibited gross reduction in the nodulation of legumes. A range of 13-57 nodules was observed in legumes from polluted soil against 476 nodules recorded for plants cultured on unpolluted soil. The heterogeneity of the microbial loads between oil-polluted and unpolluted soil were statistically significant (p < 0.05, ANOVA). Positive significant relationships were observed between the levels of hydrocarbons and the densities of heterotrophic bacteria (r = 0.91) and that of hydrocarbon utilizing bacteria (r = 0.86). On the other hand, relationships between the densities of nitrogen fixing bacteria and total hydrocarbons content was negative (r = -0.30) while positive relationships were recorded between the densities of different microbial groups and treatment periods except at 15% and 20% pollution levels. The LSD tests revealed highly significant differences (p < 0.001) in the physiological groups of soil microorganisms at all levels of pollution. The results imply that crude oil seriously affects rhizosphere microbial growth in legumes. Among the bacterial species isolated, Clostridium pasteurianum, Bacillus polymyxa and Pseudomonas aeruginosa exhibited greater ability to degrade hydrocarbons than Azotobacter sp, Klebsiella pneumoniae and Derxia gummusa while Nitrosomonas and Nitrobacter had the least degradability. A continuous monitoring of the environment is advocated to prevent extinction of nitrogen-fixing bacteria and total loss of soil fertility attributable to petroleum hydrocarbon contamination in the Niger Delta ultisol.

Biodegradation of international jet A-1 aviation fuel by microorganisms isolated from aircraft tank and joint hydrant storage systems.

Microorganisms contaminating international Jet A-1 aircraft fuel and fuel preserved in Joint Hydrant Storage Tank (JHST) were isolated, characterized and identified. The isolates were Bacillus subtillis, Bacillus megaterium, Flavobacterium oderatum, Sarcina flava, Micrococcus varians, Pseudomonas aeruginosa, Bacillus licheniformis, Bacillus cereus and Bacillus brevis. Others included Candida tropicalis, Candida albicans, Saccharomyces estuari, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, Cladosporium resinae, Penicillium citrinum and Penicillium frequentans. The viable plate count of microorganisms in the Aircraft Tank ranged from 1.3 (+/-0.01) x 104 cfu/mL to 2.2 (+/-1.6) x 104 cfu/mL for bacteria and 102 cfu/mL to 1.68 (+/-0.32) x 103 cfu/mL for fungi. Total bacterial counts of 1.79 (+/-0.2) x 104 cfu/mL to 2.58 (+/-0.04) x 104 cfu/mL and total fungal count of 2.1 (+/-0.1) x 103 cfu/mL to 2.28 (+/-0.5) x 103 cfu/mL were obtained for JHST. Selected isolates were re-inoculated into filter sterilized aircraft fuels and biodegradation studies carried out. After 14 days incubation, Cladosporium resinae exhibited the highest degradation rate with a percentage weight loss of 66 followed by Candida albicans (60.6) while Penicillium citrinum was the least degrader with a weight loss of 41.6%. The ability of the isolates to utilize the fuel as their sole source of carbon and energy was examined and found to vary in growth profile between the isolates. The results imply that aviation fuel could be biodegraded by hydrocarbonoclastic microorganisms. To avert a possible deterioration of fuel quality during storage, fuel pipe clogging and failure, engine component damage, wing tank corrosion and aircraft disaster, efficient routine monitoring of aircraft fuel systems is advocated.

Bacteriological Quality of some Pharmaceutical Products Marketed by Drug Vendors in Uyo; Nigeria

Bacteriological quality of some pharmaceutical products purchased from open markets; buses and drug stores in Uyo metropolis was studied in order to determine the level of contamination of the drugs. The drug samples examined were Tetracycline capsules; Paracetamol tablets; Ampicillin capsules; Chloroquine tablets; Chloroquine syrup; Chloroquine injections; Flagyl tablets and Chloramphenicol tablets. The bacterial count ranged from 2.3x104 cfu/g to 4.4x104 cfu/g for the 16 samples of Ampicillin; 1.2x105 cfu/g to 1.8x104 cfu/g for the 7 samples of unsealed capsules of tetratcycline; 2.9x104 cfu/g to 3.8 x104 cfu/g for the 15 samples of paracetamol; 3.8 x104 cfu/ml to 2.0 x108 cfu/ml for the 23 samples of Chloroquine injection; tablets and syrup 1.0 x104 cfu/g to 4.8 x104 cfu/g for 15 samples of Flagyl. The organisms isolated were Bacillus subtilis (19.0); Staphylococcus aureus (25.0); Aerobacter aerogenes (7.0) and Proteus mirabilis (8.0). Although the counts obtained from this work were of low levels; the presence of known pathogenic microorganisms such as Staphylococcus aureus and Proteus mirabilis in some drugs constitute a health hazard to the public