Degradation of Crude Oil by Bacteria Isolated from Various Soil Plantation at Idanre, Nigeria

Degradation of crude oil by bacteria isolated from three plantations soil at Idanre, Nigeria were comparatively investigated. Soil samples collected by hand trowel at 5cm rhizosphere of Cocoa, Orange, and Teak plantations from Idanre, Ondo State. The crude oil – forcados blend was obtained from Warri, Delta State, Nigeria. Gram negative bacteria were isolated from rhizosphere soil sample using standard microbiological methods. Preparation of Biomass was done by centrifuging nutrient broth repeatedly to wash cells. Harvested cells were obtained for the degradation of crude oil. Harvested cells were inoculated with crude oil and then incubated in a shaker. Degradation of crude oil was monitored by using spectrophotometer to read the OD at 540 nm. The bacteria isolated from rhizosphere of cocoa include: Citrobacter freundii, Yersinia pestis, Edwardsiella tarda,. Serratia marcescens. Rhizosphere of orange; Providencia stuatii while Enterobacter agglumerans, Moellerella wisconsis were isolated from rhizosphere of teak. The most effective hydrocarbon utilizing bacteria was Enterobacter agglumerans, which resulted in increase in population densities and reduction in hydrocarbon contents in the crude oil. Findings from this study shows the effectiveness of degrading hydrocarbon in liquid medium and further confirmed the potency of bacterial cells to degrade crude oil.

Alterations in Arbuscular Mycorrhizal Community Along a Chronosequence of Teak (Tectona grandis) Plantations in Tropical Forests of China

Arbuscular mycorrhizal (AM) fungi play a crucial role in promoting plant growth, enhancing plant stress resistance, and sustaining a healthy ecosystem. However, little is known about the mycorrhizal status of teak plantations. Here, we evaluated how the AM fungal communities of rhizosphere soils and roots respond to different stand ages of teak: 22, 35, 45, and 55-year-old from the adjacent native grassland (CK). A high-throughput sequencing method was used to compare the differences in soil and root AM fungal community structures. In combination with soil parameters, mechanisms driving the AM fungal community were revealed by redundancy analysis and the Mantel test. Additionally, spore density and colonization rates were analyzed. With increasing stand age, the AM fungal colonization rates and spore density increased linearly. Catalase activity and ammonium nitrogen content also increased, and soil organic carbon, total phosphorous, acid phosphatase activity, available potassium, and available phosphorus first increased and then decreased. Stand age significantly changed the structure of the AM fungal community but had no significant impact on the diversity of the AM fungal community. However, the diversity of the AM fungal community in soils was statistically higher than that in the roots. In total, nine and seven AM fungal genera were detected in the soil and root samples, respectively. The majority of sequences in soils and roots belonged to Glomus. Age-induced changes in soil properties could largely explain the alterations in the structure of the AM fungal community along a chronosequence, which included total potassium, carbon-nitrogen ratio, ammonium nitrogen, catalase, and acid phosphatase levels in soils and catalase, acid phosphatase, pH, and total potassium levels in roots. Soil nutrient availability and enzyme activity were the main driving factors regulating the shift in the AM fungal community structure along a chronosequence of the teak plantations.

Impact of Human Activities on the Distribution of Termite Communities in Teak Plantations (Tectona grandis L. F., Verbenaceae) in the Korhogo Communal Area (North Côte d'Ivoire)

Aims: This study aimed to assess the impact of human activities on termites in teak plantations in the Korhogo communal area. Methodology: Termites were sampled from October to November 2020 using the transect method recommended by Jones and Eggleton (2000). The study was carried out in three teak plantations undergoing different levels of human activities, with a forest fragment as reference area. Five types of human activity were assessed and the overall proportion of human pressure on each habitat was calculated. The species richness (S), Shannon index (H'), Evenness (E) and the relative abundance were calculated of termites for each habitat type. Analyses of variance (ANOVA) were used to compare the species richness and abundance of termites. Results: The results showed that the village plantation of teak (PVT) had the highest degree of human pressure (50.94%), followed by the teak plantation of the forest of Mount Korhogo (TFMK) (29.24%). The teak plantation of Botanical Garden (TJB) was under low pressure (6.60%). A total of 30 species grouped in 19 genera and 8 sub-families of termites were identified in all plots. Termite diversity was high in the forest fragment (19.67 ± 1.15) and in the teak plantation of Botanical Garden (21.33 ± 2.08), but low in the village teak plantation (11 ± 1). The abundance of termites evolves in the same direction as the species richness. Conclusion: Anthropogenic activities affect the trophic composition of termites, particularly the humivore group. Reconstruction of the fauna and flora of the teak forests would be beneficial for the conservation of termite species. In this region, teak forests would thus play a role as a refuge for termite communities, which are recognised as the main soil fertilising organisms in the tropics.