Information on soil organic carbon stock (SOCs) and carbohydrates (R-CHO) in soils is a prerequisite to understanding the maintenance of soil health, because they promote aggregate stability, soil aeration and the amount of CO2 in the atmosphere. The study was carried out to quantified soil organic carbon stock and acid-soluble carbohydrates in soils under different land uses in the University of Port Harcourt Research Farms and related them to maintenance of soil structural indices. The land use types were: Teak (Tectona grandis), Gmelina (Gmelina arborea), Rubber (Hevea brasilensis), and continuously cultivated plots to maize and cassava (CC). Results revealed significant changes in mean weight diameter (MWD) of water stable aggregates, acid soluble carbohydrates, and soil organic carbon storage amongst the various land use types. Mean weight diameter of the topsoil was highest in Teak (0.93 mm), followed by 0.84 mm in Gmelina soils. Acid soluble carbohydrates (R-CHO) values were 20.67, 19.80, 18.67 and 3.60 g/kg-1 for Rubber, Gmelina, Teak and (CC) soils, respectively. Cultivation of Teak, Gmelina, and Rubber, increased topsoil organic carbon stock by 102.8, 90.2, and 60.8% respectively, compared to the CC soil. The dry bulk density varied significantly (p < 0.05) in Teak at 1.28 g cm-3 and 1.68 g cm-3 in CC soils. Saturated hydraulic conductivity (Ksat) value as slow as 4.8 cm h-1 was obtained in CC, compared to rapid Ksat values of 25.0 and 22.6 cm h-1 in Teak and Gmelina, respectively. Relationships showed a strong positive linear correlations between MWD and SOCs (r= 0.873, p < 0.01) and R-CHO (r= 0.856, p < 0.01). A positive correlation of SOCs with macro aggregates explained the involvement of SOC stock in the stabilization of micro aggregates for the formation of macro aggregates which promotes soil aeration and capillary pores, thereby, preventing soil degradation and compaction. Therefore, integrating these forest plants into the farming systems would help in improving the structural indices of the soil and also store significant quantity of SOC.

The mining soils in Kingdom Saudi Arabia have accumulated heavy metals, causing considerable contamination and grave environmental danger. This research highlights the amount of metal pollution in the central part of Saudi Arabia, especially in Al Shiqqah mining area at Qassim region. The study aims to evaluate the level of trace metal contamination in the Surface soil. Also, the objective of this study to determine the degree of pollution and potential ecological harm posed by trace metals. Soil and salt samples were taken at random for four soil profiles at the surface (0–25 centimeter) and surface (25–50 centimeter). Heavy metals like manganese, nickel, cadmium, cobalt, chromium, copper and lead were measured in Al-Shiqqah mining samples by using atomic absorption spectroscopy instrument and the results were statistically analyzed. The study determined the concentrations of manganese, nickel, cadmium, cobalt, chromium, copper and lead in the surface and surface soils, to evaluate the degree of pollution and possible ecological hazards by utilizing the geo-accumulation index, contamination factor, degree of contamination and statistical analysis. Overall, the metals’ geo-accumulation index values in soil under investigation show: the subsequent downward tendency manganese¿ nickel¿ cadmium¿ cobalt¿ chromium¿ copper¿ lead. In the studied area, the geo-accumulation index associated with the seven investigated metals was high for manganese and was significantly too low for lead, cobalt, and copper. Cadmium and nickel give moderate pollution levels. Contamination levels of trace elements were calculated by contamination factor suggesting that soil was very highly contaminated with manganese and cadmium and extremely low in copper, chromium, and lead contamination, polluted with cadmium is moderately, and strongly with nickel. The degree of contamination, the readings for the soil samples showed that they were very low in lead, chromium, and copper, very high in degree of contamination with cobalt, moderately polluted with manganese and nickel, and highly contaminated with cadmium. According to the findings, the manganese concentrations in soil samples for the surface, salt, surface at depth 25 centimeter and surface at depth 50 centimeter were determined to be 5427.7998, 656.6250, 7037.7002, and 6853.7002 milligram per kilogram, respectively. These results were discovered to be greater than the WHO-permitted limits, which are 740 milligram per kilogram for soil. The result illustrated that the contamination with heavy metals was high when in contrast to the soil’s standard concentration of trace elements. Generally, it is possible to determine the natural or anthropogenic sources of heavy metals in soils by using multivariate analysis in conjunction with geo-accumulation index, contamination factor, degree of contamination value as helpful tools. The information gained can be used to better plan and implement remediation efforts and enhance the environmental conditions in areas affected by mining soil.

Recent advances in anaerobic digestion has resulted in expansion of sustainable methods for use of waste as energy resources. Conventional methods prove to be uneconomical and environmentally impractical. Moreover, the microbial consortia in anaerobic digestion are temperature dependent and therefore requires investigations on temperature optimization. Therefore, the recent experimental study is being undertaken with the objective in order to assess the effect of temperature on anaerobic biodegradation of food wasted from a hostel campus. The effect of temperature on methane generation rate has also been investigated. The anaerobic digestion study under psychrophilic, mesophilic and thermophilic temperature conditions has been carried out and compared in order to assess the optimum methane production conditions. All the experimental study for anaerobic digestion of food waste has been carried out at optimum F/M (food to mass) ratio of 0.75. The cumulative highest methane production is observed to be 33, 50 and 65 mL of CH4 in reactor R1, R2 and R3 with initial food waste COD dosage of 100, 150 and 200 mg, respectively under mesophilic temperature conditions. The highest biochemical methane potential (BMP) value of 0.94, 0.95 and 0.93 gCH4-COD/gCOD fed in reactor R1, R2 and R3 respectively, under mesophilic temperature conditions. It been observed that for maximum methane generation rate constant of 0.62 d-1 were observed under thermophilic conditions thus has to be highly accelerative process but overall conversion of organic matter to methane is less as compared to mesophilic temperature conditions, this is because free ammonia concentration increases with increasing temperature, by influencing the equilibrium. However, mesophilic conditions provide a more stable environment for the anaerobic digestion process. This may be due to the fact that temperature fluctuations can disrupt the microbial activity and slow down the process, but mesophilic conditions provide a stable environment for the microorganisms to thrive. Therefore, the mesophilic temperature range provides a balance between high reaction rates, stability, and cost-effectiveness, making it the optimal temperature range for anaerobic digestion of food waste. The obtained results in present study will be helpful in implementing on full-scale anaerobic solid waste digesters for enhancing the methane generation under mesophilic temperature conditions with high organic matter removal. Also, under thermophilic conditions the energy requirement for heating proves to be uneconomical.

Biofilm formation has different stages and can be classified based on the bacterial strain, culture vessel, and the method employed. Biofilm formation is carried out in culture vessels to represent mode of infection in humans. Microbial concentration, growth medium, supplement, and incubation time are key factors to successfully form biofilm in a culture vessel. This study aimed to identify the optimum conditions for biofilm formation in a 96-well plate by culturing Pseudomonas aeruginosa and Streptococcus pyogenes. We utilized the infectious and pathogenic bacteria, P. aeruginosa and S. pyogenes strains. These bacteria were cultured in Mueller–Hinton Broth (MHB) and Tryptic Soy Broth (TSB) at two different optical densities OD600 (0.05) and OD600 (0.1). After a certain incubation time, the formed biofilm was stained by using 0.1% crystal violet. The stained bacteria were disaggregated and measured using a microplate reader. Biofilm was then classified based on bacterial adherence to the plate. Our results showed that P. aeruginosa and S. pyogenes biofilms were strongly formed on days 3 and 5 in MHB and TSB, respectively. However, the strongest biofilm formation was seen on day 3 after P. aeruginosa being incubated in MHB at OD600 (0.1) and after S. pyogenes being incubated in MHB at OD600 (0.05). Biofilm formation is ranged between weak, moderate, and strong in accordance with the density of bacterial adhesion. P. aeruginosa and S. pyogenes biofilms were optimized at specific OD600 (0.1 and 0.05, respectively) for 3 days’ cultivation in MHB.

Phenol is one of the main pollutants that have a serious impact on the environment and can even be very critical to human health. The biodegradation of phenol can be considered an increasingly important pollution control process. In this study, the degradation of phenol by Bacillus simplex was investigated for the first time under different growth conditions. Six different initial concentrations of phenol were used as the primary substrate. Culture conditions had an important effect on these cells' ability to biodegrade phenol. The best growth of this organism and its highest biodegradation level of phenol were noticed at pH 7, temperature 28 °C, and periods of 36 and 96 h, respectively. The GC-MS analysis of the bacterial culture sample revealed that further degradation of the catechol by 1,2-dioxygenase produce a cis, cis-mucconic acid via ortho-pathway and/or by 2,3-dioxygenase into 2-hydroxymucconic semialdehyde via meta-pathway. The highest biodegradation rate was perceived at 700 mg/L initial phenol concentration. Approximately 90% of the phenol (700 mg / L) was removed in less than 96 hours of incubation time. It was found that the Haldane model best fitted the relationship between the specific growth rate and the initial phenol concentration, whereas the phenol biodegradation profiles with time could be adequately described by the modified Gompertz model. The obtained parameters from the Haldane equation are: 1.05 h−1, 9.14 ppm, and 329 ppm for Haldane's maximum specific growth rate, the half-saturation coefficient, and the Haldane’s growth kinetics inhibition coefficient, respectively. The Haldane equation fitted the experimental data by minimizing the sum of squared error (SSR) to 1.36 X 10-3.

Applied Environmental Biotechnology (AEB) is an open access journal published by Urban Development Scientific Publishing. AEB provides a forum in the broad research field of biotechnology in terms of biotechnology, environmental, microbial, metabolism, degradation, bioproducts, et al.

Bioflocculants are commonly used in wastewater treatment. In this study, an efficient bioflocculant-producing strain, Bacillus sp. R1, was isolated and identified; strain R1 could efficiently produce bioflocculant BF-R1 with wheat bran hydrolysate. The characteristics and flocculation mechanisms of BF-R1 were determined and it was then applied for the granular carbon particles treatment in wastewater. Notably, 3.71 g of BF-R1 were produced when 200 mL/L wheat bran hydrolysate was used as the sole carbon and nitrogen source. BF-R1 contained polysaccharides, proteins, and glycoproteins and showed a good flocculating efficiency of 91.00% for granular carbon particles in contaminated wastewater when 3.50 g/L BF-R1 was added, thus achieving successful recycling of fine particle-contaminated wastewater. Taken together, our findings for the first time demonstrate that BF-R1 fermented using WBH can probably be a promising candidate agent for wastewater management processes.

The base excision repair (BER) pathway is an essential defense mechanism against oxidative damage of DNA in plants. Previous studies have reported that chromium (Cr) exposure causes oxidative stress and DNA damage due to accumulation of ROS. In this study, hydroponic experiments were carried out to investigate mRNA expression of 21 candidate genes involved in the BER pathway in rice seedlings exposed to Cr(III) using qRT-PCR. Changes of H2O2 and O2-• content in rice tissues and the relative growth rate (%) of rice seedlings were also determined. The results indicated that Cr(III) induced dose-dependent inhibition on the relative growth rate of rice seedlings. H2O2 content in roots were significantly increased. Changes of the content of H2O2 and O2-• in shoots was consistent. PCR analysis revealed that responses of selected 21 candidate genes to Cr(III) exposure were tissue specific. The BER pathway in roots was repressed by Cr(III) treatment but activated in shoots in response to Cr(III) exposure, suggesting that the BER pathway would play different roles in regulating and repairing DNA damage caused by Cr(III) exposure in rice.

This study was carried out to estimate N-15 allocation into different components of the above- and below-ground plant parts, and to quantify biological N-fixation in faba bean using N-15 dilution method, and both canola and barley as reference crops. Four samplings were conducted during the crop growing season, both above- and below-ground plant parts, and soil were sampled. The above-ground plant was fractionated into leaves, stems, shell, and seeds for faba bean and canola; and dead-leaves, live-leaves, stems, sheaths, husks, and seeds for barley. Roots were extracted from soil by root-washing technique and further separated from dead debris by water floatation and hand-picking. N-15 excess of faba bean above-ground parts was lower than its roots, but the reverse was true for the non-legumes (canola and barley). N-15 fractionation was apparently taking place in various plant parts. Reproductive organs of faba bean had lower N-15 excess than the vegetative ones, but reproductive organs of non-legumes (canola and barley) had higher N-15 excess than the vegetative ones. N-fixation in faba bean was quantified by using N-15 dilution method with either canola or barley as a reference crop, the quantity of N derived from atmospheric fixation was 183-199 kg N/ha/yr in the above-ground parts of faba bean and 18-22 kg N/ha/yr in faba bean roots by September 1, when faba beans were not fully matured. Either canola or barley can be a valid reference crop for N-fixation estimation in N-15 dilution method. Total difference method agreed with N-15 dilution method with less than 10% variation in this study. A peak of N-fixation was observed after faba bean flowering and the rate of N-fixation during this period was 4.0-4.7 kg N /ha/day. This study provides the key inofmration for the quantity of N-fixation from atmosphere in faba bean growing on this soil of Canada.

Bioleaching has been applied as a successful technique for metal recovery from various mineral sources like low-grade ores, waste materials and tailings. Mixed cultures of bioleaching microorganisms have a high performance in mineral dissolution. Thus far, microbial interactions in bioleaching communities are poorly understood. In this paper, the acidophilic archaeon Ferroplasma acidiphilum and the bacteria Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans were chosen to study their interactions during pyrite leaching. The initial attachment to pyrite and pyrite leaching efficiency of pure and mixed populations were investigated. The data indicate: (i) attachment and bioleaching efficiency of L. ferriphilum was reduced in the presence of F. acidiphilum. However, the combination of F. acidiphilum and S. thermosulfidooxidans showed increased leaching, although the initial attachment rate was reduced, when compared to pure cultures. Thus, synergistic or antagonistic interactions may exist between F. acidiphilum and S. thermosulfidooxidans or F. acidiphilum and L. ferriphilum, respectively; (ii) pre-established biofilms of L. ferriphilum inhibited initial attachment to pyrite by cells of F. acidiphilum and did not promote pyrite leaching by F. acidiphilum. In contrast, inactivated biofilm cells of S. thermosulfidooxidans enhanced pyrite bioleaching by F. acidiphilum; (iii) adhesion forces of cells to an AFM tip (Si3N4) seemed to be not correlated to attachment and bioleaching capacity; and (iv) lectins were applied to show and distinguish single species in mixed biofilm populations. Physical contact between cells of S. thermosulfidooxidans and F. acidiphilum was visible.