Impact of different nitrogen amendments on the biodegradation of 14C-phenanthrene by endophytic fungal strains in liquid culture.

In this study, the biodegradation of phenanthrene was investigated in newly isolated endophytic fungal strains, Fusarium sp. (KTS01), Trichoderma harzianum (LAN03), Fusarium oxysporum (KTS02), Fusarium oxysporum (LAN04), and Clonostachys rosea (KTS05). This was performed under different carbon:nitrogen ratios (10:1, 20:1, and 30:1) using different nitrogen sources (urea and malt extract and ammonium nitrate) over a 30 d incubation period in both static and agitated liquid media. The kinetics of polycyclic aromatic hydrocarbons (PAH) mineralisation to CO2 (lag phases, fastest rates, and overall extents) were measured for all of the fungal strains and nutrient conditions using 14C-phenanthrene. All fungal strains were able to biodegrade 14C-phenanthrene to 14CO2 under the different nutrient amendments. However, 14C-phenanthrene mineralisation varied for most of the fungal strains in static and agitated culture conditions. Greater extents of mineralisation were found in fungal cultures (strains KTS05 and KTS01) with C:N ratio of 10:1 in both static and agitated conditions, while the fungal strains (KTS05 and LAN03) showed the greatest phenanthrene mineralisation after N source amendments, particularly with malt extract. In addition, the phenanthrene mineralisation increased with higher C:N ratios for Clonostachys rosea (KTS05) only. Consequently, the results reported here provide a promising potential for the endophytic fungal strains and the importance of nutrients amendments for the enhanced degradation of PAHs contaminated environments.

Evaluation of the effects of abattoir effluent on the physicochemical and bacteriological quality of River Benue, Nigeria.

This study investigated the impact of continual discharge of untreated abattoir effluents on the water quality of River Benue. Three major abattoirs (Wurukum, Wadata and Northbank) in Makurdi, Nigeria, and their polluting strength in river upstream and downstream were measured and compared. Two water quality parameters: physicochemical and bacteriological were investigated. Water quality index (WQI) was computed for all sampling sites. Results revealed that some of the physiochemical parameters were above recommended limits, especially in downstream river, in particular, the turbidity (24.0-55.5 mg/l), TSS (62.6-92.0 mg/l), DO (8.0 mg/l), and total hardness (160-240 mg/l). All sampling sites indicated an increased bacterial population while Salmonella spp. and Escherichia coli were the predominant bacteria among the ten genera identified in water upstream and downstream. Faecal coliforms increased from upstream to downstream in two sampling sites (Wurukum and Wadata). Strong positive correlations were observed between upstream and downstream samples for pH, EC, turbidity, TSS, DO, COD, SO42-, TC, and Shigella spp. WQI revealed that all sampling locations were heavily polluted and unsuitable for drinking purposes (WQI > 300) based on both the physicochemical and bacterial parameters. The sampling sites, however, showed excellent water quality based only on physicochemical properties especially upstream at both Wurukum and Northbank sampling sites (WQI < 50). It was suggested that anthropogenic activities around the river may be responsible for the high concentration of some physiochemical parameters and bacterial loads observed in the river downstream. Moreover, it was concluded that microbial loads should be fully considered in WQI computation in terms of water quality. Our results are useful for water resource and waste management in terms of practices and policy guidance, especially for developing countries.

Impact of lignocellulosic waste-immobilised white-rot fungi on enhancing the development of 14C-phenanthrene catabolism in soil.

In this study, an investigation was carried out to explore the the impact of white-rot fungi (WRF) on enhancing the development of phenanthrene catabolism in soil over time (1, 25, 50, 75 and 100 d). The WRF were immobilised on spent brewery grains (SBG) prior to inoculation to the soil. The results showed that SBG-immobilised WRF-amended soils reduced the lag phases and increased the extents of 14C-phenanthrene mineralisation. Greater reductions in the lag phases and increases in the rates of mineralisation were observed in immobilised Trametes versicolor-amended soil compared to the other WRF-amendments. However, the presence of Pleurotus ostreatus and Phanerochaete chrysosporium influenced biodegradation more strongly than the other fungal species. In addition, fungal enzyme activities increased in the amended soils and positively correlated with the extents of 14C-phenanthrene mineralisation in all soil amendments. Maximum ligninolytic enzyme activities were observed in P. ostreatus-amended soil. Microbial populations increased in all amended soils while PAH-degrading fungal numbers increased with increased soil-PAH contact time and strongly positively correlated with fastest rates of mineralisation. The findings presented in this study demonstrate that inoculating the soil with these immobilised WRFs generally enhanced the mineralisation of the 14C-phenanthrene in soil. This has the potential to be used to stimulate or enhance PAH catabolism in field-contaminated soils.