Diversity and community structure of bats (Chiroptera) in the Centre Region of Cameroon

In this survey, we investigated the diversity and community structure of bats in the Centre Region of Cameroon with respect to their distribution in the different vegetation zones of the region. We mist-netted bats monthly from January 2016 to June 2017 for five nonconsecutive nights per month. Thirty-nine sites were surveyed: 24 in traditional farms, nine in the savannah and six in the forests. A total of 668 bats were captured during 81 nights of capture, covering seven families, 21 genera and 36 species. This included 26 species in traditional farms, 13 species in savannah and 11 species in the forest. Micropteropus pusillus was the most abundant species (30.7%) recorded, followed by Hipposideros ruber (24.9%). The sample efficiency was estimated at 72.1% with fitted species accumulation curves not reaching asymptotes for the three habitat types, suggesting that the survey did not record all the bats present. There was an indication of general increased in abundance of bats during the dry and rainy seasons but it is not significant (Mann–Whitney U: 783.5, p = .195). The rarity index was highest in traditional farms (0.44), followed by savannah (0.38) and then forest (0.33). This preliminary survey provides baseline data on the distribution of bats in the different vegetation types in the Centre Region of Cameroon.     

Biological Degradation of Crude Oil Refinery Sludge with Commercial Surfactant and Sewage Sludge by Co-Composting

This study determined the potential of surfactant and sewage sludge in enhancing degradation of oil sludge. A mixture of oil sludge, surfactant, and sewage sludge was co-composted for 24 weeks in the laboratory. Physical and chemical parameters in the compost were measured every four weeks. Isolated microorganisms were characterized by molecular techniques. The pH in all experiments remained between 8 and 6.4. CO₂ evolution reached 5503 µg/dwt/day by the twenty-fourth week. The dominant bacterial species were Acinectobacter, Rodococcus, mycobacterium, Pseudomonas, Bacillus, Arthrobacter, and Staphylococcus species and fungi were Pleurotus, Penicillium, and Aspergillus sp. TPH was reduced by 92% in the sewage sludge and surfactant treatment, 75 and 81% in other treatments, and 44.2% in the control. PAH concentrations were reduced by between 75 and 100%. The results indicate that a careful application of surfactant and sewage sludge could enhance oil sludge degradation in a compost system.     

Biodegradation of polyacyclic aromatic hydrocarbons in contaminated soil by biostimulation and bioaugmentation in the presence of copper(II) ions

The effect of a combination of biostimulation, bioaugmentation and the presence of CuSO₄ on the biodegradation of the polycyclic aromatic hydrocarbons (PAHs) dibenzofuran 210 mg kg⁻¹, benzo(a)anthracene 200 mg kg⁻¹, dibenzo-p-dioxine 100 mg kg⁻¹ and 9-fluorenone 100 mg kg⁻¹ in a sandy loam soil was studied. The pH of the soil was raised from 5 to 7 with agricultural lime. The soil was then divided into two sets labelled Treatments A and B. Six subsets numbered 1–6 were established for each of Treatments A and B. Treatment A was not amended with CuSO₄ while Treatment B was amended with 5% CuSO₄. Sterile control was established for both sets of treatment by adding 75 g sodium azide twice during the treatment period to Treatment 1. Treatment 2 was established as a natural control, without further amendments. Treatments 3–6 were tilled daily and maintained at 70% moisture. Mono-ammonium phosphate (MAP) (1 g kg⁻¹ soil) was added to Treatments 4–6 twice during the treatment period. H₂O₂ at 500 mg l⁻¹ (600 μl of a 39% solution) was added weekly to Treatment 5. A biosupplement was added to Treatment 6 every week. The experiments were incubated for 10 weeks at ambient temperature. The C:N:P ratio of the soil after the addition of MAP was 38:1:2.2. Counts of microorganisms were larger in the treatments not amended with CuSO₄. For example counts were 77×10⁶ in A6, as compared to 61×10⁶ in B6. CO₂ evolution was also consistently lower in the CuSO₄-amended treatments. Reduction in the concentrations of the PAHs in the treatments without CuSO₄ reached a maximum of 28.6% (dibenzofuran) in the sterile control and 39.1% (dibenzofuran) in the natural control. In contrast, maximum reduction in Treatment 3 reached 85% (dibenzofuran). Reduction in Treatments 4, 5 and 6 was between 90% and 100% in both Treatments A and B after 10 weeks. The combination of biostimulation and bioaugmentation (Treatment 6) enhanced PAH reduction by 100% reduction of all PAHs tested, better than only biostimulation (Treatments 4 & 5), which reduced the PAHs concentrations by between 90% and 100%. The effect of CuSO₄ on the biodegradation of the tested PAHs was more prominent during the early stages of the experiment. However, there was no significant difference in the overall residual concentrations of the PAHs in both treatments A and B at the end of the treatment period.     

Optimization of soil physical and chemical conditions for the bioremediation of creosote-contaminated soil

Mispah type soil (FAO : Lithosol) contaminated with >250 000 mg kg^-1 creosote was collected from the yard of a creosote treatment plant. The soils carbon, nitrogen and phosphorus contents were determined. Due to creosote contamination, thecarbon content of the soil was found to be 130,000 mg C kg^-1. This concentration was found to greatly affect the nitrogen content (0.08%). The phosphorus content was less affected (4.5%). It was estimated that a nutrient amendment to bring the soil to a C : N 10 : 1 would be adequate to stimulate microbial growth and creosote degradation. The soil was amended with a range of C : N ratios below and above the estimated ratio. In one of the treatments, the phosphorus content was amended. Sterile and natural controls were also set up. The soil was incubated at 30 °C on a rotaryshaker at 150 rpm in the dark for six weeks. Water content was maintained at 70% field capacity. The lowest nitrogen supplementation (C : N = 25 : 1) was more effective in enhancing microbial growth (3.12E + 05) and creosote removal (68.7%) from the soil. Additional phosphorus was not very effective in enhancing the growth of microorganisms and removal of creosote. The highest nitrogen supplementation(C : N = 5 : 1) did not enhance microbial growth and creosote removal.A relationship between mass loss and creosote removal was also observed. Phenolics and lower molecular mass polycyclic aromatic hydrocarbons (PAHs) were observed to be more susceptible to microbial degradation than higher molecular mass compounds. Nutrient concentration, moisture content and pH were thus observed to play very significant roles in the utilization of creosote in soil. These results are being used for the development of a bioremediation technology for the remediation of creosote contaminated soils in a treatment plant in South Africa.     

The potential of Chromolaena odorata (L) to decontaminate used engine oil impacted soil under greenhouse conditions

This study reports on the use of Chromolaena odorata (L) R.M. King and H. Robinson, an Asteraceae (compositae) and an invasive alien weed in Africa for the remediation of soil contaminated with used engine oil. Used engine oilfrom a motor service garage was used to artificially contaminate soil taken from a garden to give total petroleum hydrocarbon (TPH) of between 1 and 40 g kg(-1). Chromolaena odorata (L), propagated by stem cuttings were transplanted into the contaminated soil and watered just enough to keep the soil at about 70% water holding capacity for 90 day. A set of control experiments containing 40 g kg(-1) used engine oil but without plants was set up. All experiments were set up in triplicates. Although the plants in the experiments containing higher than 30 g kg(-1) used engine oil showed relatively slower growth (fewer branches and leaves, and shorter in height) compared to those containing lower concentrations, the plants in all the experiments continued to grow until the end of the 90 day period. Residual TPH after 90 days showed that between 21 and 100% of oil was lost from the planted soil while only 11.5% was lost in the control, which did not contain plants during the same period. Analysis of plant tissues showed that both shoot and root tissues contained detectable levels of TPH and selected PAHs were also detectable. Biomass accumulation by Chromolaena odorata was affected adversely by concentrations of oil higher than 20 g kg(-1). Results of germination rates and germination energy measurements showed that Chromolaena odorata was able to reduce the toxicity of the contaminated soil after 90 days as compared to soils containing freshly contaminated soiL     

Co-Composting of Soil Heavily Contaminated with Creosote with Cattle Manure and Vegetable Waste for the Bioremediation of Creosote–Contaminated Soil

Mispah form (FAO: Lithosol) soil contaminated with >380 000 mg kg^?1 creosote was co-composted with cattle manure and mixed vegetable waste for 19 months. The soil was mixed with wood chips to improve aeration and then mixed with cattle manure or mixed vegetable waste in a ratio of 4:1. Moisture, temperature, pH, ash content, C:N ratios, and the concentrations of creosote in the compost systems were monitored monthly. The concentrations of selected hydrocarbons in the compost systems were determined at the end of composting. Temperature rose to about 45°C in the cattle manure compost within two months of incubation while temperature in the control and vegetable waste remained below 30°C until the fourth month. Creosote concentration was reduced by 17% in the control and by more than 99% in the cattle manure and vegetable waste compost after composting. The rate of reduction in concentration in the mixed vegetable waste compost was initially lower than in the cattle manure compost. The reduction rate became similar in later months with only small differences towards the end of the composting. The concentrations of selected creosote components were reduced by between 96% and 100% after composting. There was no significant difference in reduction in concentration in both compost systems at p 0.05. Microbial activity correlated with reduction in creosote concentration.     

Co-composting of PAH-contaminated soil with poultry manure

AIMS: To investigate the effects of co-composting poultry manure with soil contaminated with different concentrations of polycyclic aromatic hydrocarbons (PAHs), on the degradation of selected PAHs in a static-pile compost system. METHODS: Mispah form (Food & Agricultural Organisation, FAO : lithosol) soil contaminated with PAHs was co-composted with poultry manure for 19 months. The soil was mixed with wood chips in a ratio of 1:1 to improve aeration and then mixed with poultry manure in a ratio of 4:1. A data logger measured temperature monthly. Residual concentrations of selected PAHs in the compost were determined monthly by gas chromatography/flame ionisation detection (GC/FID). Moisture, pH, ash content and C:N ratios were also monitored monthly. Microbial activity was measured by measuring CO(2) evolution. CONCLUSIONS: The results obtained in this experiment have shown that co-composting poultry manure with PAH-contaminated soil is capable of removing large concentrations of high molecular weight PAH from contaminated soil to levels below 1 mg kg(-1) in 19 months. SIGNIFICANCE AND IMPACT OF THE STUDY: The paper adds to the body of knowledge necessary for the development of a cost effective technology for the remediation of soil contaminated with high molecular weight PAHs by providing information on the behaviour of selected PAHs and factors such as nutrient ratio, temperature and pH during composting.     

Bioremediation of creosote-contaminated soil in South Africa by landfarming

AIMS: To determine the combined effects of biostimulation and bioaugmentation in the landfarming of a mispah form (lithosol; food and Agriculture Organisation (FAO)) soil contaminated with >310000 mg kg-1 creosote with a view to developing a bioremediation technology for soils heavily contaminated with creosote. METHODS AND RESULTS: The excavated soil was mixed with 2500 kg ha-1 dolomitic lime and 2000 kg ha-1 mono-ammonium phosphate (MAP) before spreading over a treatment bed of shale reinforced with clay. Sewage sludge (500 kg) was ploughed into 450 m3 of contaminated soil in the second and sixth months of treatment. A further 1000 kg ha-1 MAP was added to the soil at the end of the fifth month. Moisture was maintained at 70% field capacity. Total creosote was determined by the US Environmental Protection Agency (EPA) method 418.1 and concentrations of selected creosote components were determined by gas chromatography/flame ionisation detection (GC/FID). Total creosote was reduced by more than 90% by the 10th month of landfarming. The rate of reduction in creosote concentration was highest after the addition of sewage sludge. The three-ring PAHs were more slowly removed than naphthalene and the phenolic compounds. The four- and five-ring PAHs, although persist until the end of treatment, were reduced by 76-87% at the end of the experiment. CONCLUSIONS: A combination of biostimulation and bioaugmentation during landfarming could enhance the bioremediation of soils heavily contaminated with creosote. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides information on the management of a combination of biostimulation and bioaugmentation during landfarming, and contributes to the knowledge and database necessary for the development of a technology for bioremediating creosote-contaminated land.     

Profiling of plants at petroleum contaminated site for phytoremediation

The paucity of information in the literature on the characteristics of plants that could be used for phytoremediation of petroleum hydrocarbons (PHC)-contaminated sites was the principal reason for this study. The aim of the study was to identify indigenous plants growing in PHC-impacted soil in Umuahia in eastern-Nigeria that have the ability to phytoremediate soils contaminated with hydrocarbons under tropical monsoon climate conditions. A total of 28 native plant species from different families growing in and around hydrocarbon-impacted soil in the vicinity of vandalized pipelines carrying petroleum products were collected and studied for their ability to grow in a hydrocarbon-impacted soil and remove the PHC from the impacted soil. Some of the plants demonstrated the ability to grow in soil with high levels of the total petroleum hydrocarbons (TPH), which shows that they may be tolerant to hydrocarbons in soil and could potentially phytoremediate a hydrocarbon-contaminated soil. Chromolaena odorata, Aspilia africana, Chloris barbata, Pasparlum vaginatum, Bryophyllum pinnatum, Paspalum scrobiculatum, Cosmos bipinnatus, Eragrostis atrovirens, Cyperus rotundus, and Uvaria chamae showed tendencies to phytoremediate contaminated soil. By using bioaccumulation coefficient (BAC) as a measure of phytoremediation, results showed that C. odorata, A. africana, and U. chamae demonstrated the highest potentials to phytodegrade hydrocarbons in soil.     

Identification and characterization of PAH-degrading endophytes isolated from plants growing around a sludge dam

Abstract

This study involved the isolation of bacteria endophytes with PAH-degrading ability from plants growing around a sludge dam. A total of 19 distinct isolates that were morphologically identified were isolated from 4 species of plant with a follow-up confirmatory identification using the molecular technique. Polymerase chain reaction (PCR) of the 16S rRNA gene with specific primers (16S-27F PCR and 16S-1491R PCR) was carried out. The sequence of the PCR products was carried out, compared with similar nucleotides available in GenBank. Results of the phylogenetic analysis of the isolates indicated their belonging to 4 different clades including Proteobacteria, Actinobacteria, Cyanobacteria, and Firmicutes. These were related to the genera Bacillus, Pseudomonas, Terribacillus, Virgibacillus, Stenotrophomonas, Paenibacillus, Brevibacterium, Geobacillus, Acinetobacter. From the result, Pseudomonas demonstrated a high incidence in the plants sampled. The in-vitro degradation study and the presence of dioxygenase genes indicated that these lists of endophytes are able to use the list of PAHs tested as their source of food and energy leading to their breakdown. This means that the bacterial endophytes contributed to the remediation of petroleum hydrocarbons in planta, a situation that may have been phytotoxic to plant alone. Therefore, these bacteria endophytes could be potential organisms for enhanced phytoremediation of PAHs.