جستجوی مقالات مرتبط با کلیدواژه « تجزیه بیولوژیک » در نشریات گروه « آب و خاک »

Petroleum aromatic hydrocarbons are important sources of soil and environmental pollution in our country especially around oil refineries. In order to remove these pollutants, biological methods using native microorganisms of oil contaminated soils are preferred because of their cheapness and availability. Existing soil microorganisms use these hydrocarbons as carbon and energy sources and finally produce water, CO2, biomass and harmless materials. In the present study, the sampling was conducted from different unpolluted soils of Tabriz city and oil-polluted soils of Tabriz Petroleum Refinery. The soil suspensions were cultured in YGM and SCA media and finally, 100 microbial isolates were obtained. Phenanthrene at a rate of 1000 mg/L was added to the MHB medium and then the fixed amounts of these bacterial isolates were added separately. They were incubated in shaker with 130 rpm, at 28˚C for one week. The rate of phenanthrene destruction was evaluated by spectro photometery. Thereafter the reliability of primary aromatic compounds was assayed by TLC method. Eighty-seven bacterial isolates with phenanthrene destruction rates of 3.2-93.8% were selected. Some secondary metabolites originated from destruction of hydrocarbons were subjected to the GC-Mass analysis. Some non- toxic mediatory substances were identified as result of phenanthrene biological degradation. Bacterial isolates possessing of phenanthrene degradation up to 50% were identified. By improving the growth and proliferation of effective bacteria it will be possible to remediate polluted soils from PAHs in industrial pilots.

Recently, the use of microorganisms for conversion of plant biomass into many commercially valuable products has been studied. In this study, some soil samples, composting plant materials, and composted manure from different parts of Markazy province were collected to isolate and identify aerobic bacteria, which have been capable of utilizing lignin preparations as a sole source of carbon. Bacteria were isolated by using three types of lignin preparations and hot- water- extracted wheat stover and saw dusts. Two of the isolates, identified as Streptomyces sp. and Pseudomonades sp. were able to degrade wheat stover and saw dust lignin and polysaccharides. The growth rate of Streptomyces sp. and Pseudomonades sp. was higher in wheat stover fed cultures than the saw dust fed cultures. Results also showed that bacteria treatment of lignocelluloses and nitrogen supplementation of culture media had considerable effects on chemical composition of wheat stover and saw dust. All two bacteria genera increased crude protein, APPL, soluble lignin, and decreased carbohydrates and insoluble lignin of wheat stover and saw dust (P<0.01). Streptomyces showed more degradation ability than Pseudomonades, especially in culture media containing wheat stover. The utilization of yeast extract (as nitrogen source) improved degradation abilities of bacteria. The findings of this study indicate that these bacteria could be used for biological upgrading of agriculture residues in order to feed animals.