Variance in Protease, Dehydrogenase, Phosphatase and Respiratory Activities during Phytoremediation of Crude Oil Polluted Agricultural Soil Using Schwenkia americana L. and Spermacoce ocymoides Burm. f.

Aims: To investigate the variation in the activities of some soil enzymes and microbial respiration during phytoremediation of crude oil polluted agricultural soil. Study Design: Indigenous plants of a crude oil polluted agricultural farmland were harvested and identified. Two species (Schwenkia americana L. and Spermacoce ocymoides Burm. f.) were selected for this study. Nursery was set up using sterile soil and mature and viable seeds of selected species, and germinated seedlings were transplanted into an 8 kg potted homogenised polluted soil for remediation. Place and Duration of Study: Polluted agricultural soil from Ogoniland Nigeria, University of Port Harcourt ecological garden, between May 2017 and February 2018. Methodology: Protease activity was determined based on the amino acids released after incubation of soil with sodium caseinate. Phosphatase activities determination was based on determining the degradation extent of ρ-nitrophenol phosphate (PNPP) by the samples. Dehydrogenase activity was determined based on estimation of 2,3,5- triphenyltetrazolium chloride (TTC) reduction to triphenyl formazan (TPF) in soils after incubation. The substrate induced method was adapted to estimate the respiratory activity. Organic matter was determined by weight loss on ignition method. Results: Dehydrogenase activities in remediated groups increased after 4 weeks but decreased at the end of the remediation period. Protease and phosphatase activities, and soil organic matter of remediated groups reduced over time while the soil microbial respiratory activity reduced at the end of 12 weeks remediation. There was a restoration of the polluted soils by the treatments towards normalcy with regards to activities of proteases, acid and alkaline phosphatases, and dehydrogenases. Conclusion: Soil microbial activities can reflect soil quality, and soil enzyme activities can directly reflect the metabolic need and nutrient availability of soil microorganisms. The extracellular enzymes (protease, dehydrogenase, acid and alkaline phosphatase) were shown to vary with crude oil pollution relative to time thus indicating ameliorative effects.

Humic fractions of forest, pasture and maize crop soils resulting from microbial activity

Humic substances result from the degradation of biopolymers of organic residues in the soil due to microbial activity. The objective of this study was to evaluate the influence of three different ecosystems: forest, pasture and maize crop on the formation of soil humic substances relating to their biological and chemical attributes. Microbial biomass carbon (MBC), microbial respiratory activity, nitrification potential, total organic carbon, soluble carbon, humic and fulvic acid fractions and the rate and degree of humification were determined. Organic carbon and soluble carbon contents decreased in the order: forest > pasture > maize; humic and fulvic acids decreased in the order forest > pasture=maize. The MBC and respiratory activity were not influenced by the ecosystems; however, the nitrification potential was higher in the forest than in other soils. The rate and degree of humification were higher in maize soil indicating greater humification of organic matter in this system. All attributes studied decreased significantly with increasing soil depth, with the exception of the rate and degree of humification. Significant and positive correlations were found between humic and fulvic acids contents with MBC, microbial respiration and nitrification potential, suggesting the microbial influence on the differential formation of humic substances of the different ecosystems.

Effects of brain mitochondrial uncoupling protein content and activity in rat exposed to hypoxia simulating high altitude on mitochondrial energy synthesis / 第三军医大学学报

Objective To observe the changes of rat brain mitochondrial uncoupling protein (UCP) content and activity, and explore the effect of UCP on mitochondrial energy metabolism during hypoxia exposure. Methods Adult SD rats were set randomly into control and hypoxia group (n=8 in each group). The rats of hypoxia group were put into a hypobaric chamber simulating 5000-meter high altitude for 3 days (23 h/d). The brain mitochondria was isolated by centrifugation. Mitochondrial oxidative respiratory function was measured by Clark oxygen electrode. Mitochondrial membrane potential was detected by Rhodamine123 method. The content of adenine nucleotide pool (ATP, ADP, AMP) in mitochondria was measured by high performance liquid chromatography. UCP content and activity were detected by [~ 3 H]-GTP binding method. Results High altitude hypoxia resulted in significant increase of UCP activity and a 2.9-fold rise of UCP content of rats (P