An animal charcoal contaminated cottage industry soil highlighted by halophilic archaea dominance and decimation of bacteria.

An animal charcoal contaminated cottage industry soil in Lagos, Nigeria (ACGT) was compared in an ex post facto study with a nearby unimpacted soil (ACGC). Hydrocarbon content was higher than regulatory limits in ACGT (180.2 mg/kg) but lower in ACGC (19.28 mg/kg). Heavy metals like nickel, cadmium, chromium and lead were below detection limit in ACGC. However, all these metals, except cadmium, were detected in ACGT, but at concentrations below regulatory limits. Furthermore, copper (253.205 mg/kg) and zinc (422.630 mg/kg) were above regulatory limits in ACGT. Next generation sequencing revealed that the procaryotic community was dominated by bacteria in ACGC (62%) while in ACGT archaea dominated (76%). Dominant phyla in ACGC were Euryarchaeota (37%), Pseudomonadota (16%) and Actinomycetota (12%). In ACGT it was Euryarchaeota (76%), Bacillota (9%), Pseudomonadota (7%) and Candidatus Nanohaloarchaeota (5%). Dominant Halobacteria genera in ACGT were Halobacterium (16%), Halorientalis (16%), unranked halophilic archaeon (13%) Salarchaeum (6%) and Candidatus Nanohalobium (5%), whereas ACGC showed greater diversity dominated by bacterial genera Salimicrobium (7%) and Halomonas (3%). Heavy metals homeostasis genes, especially for copper, were fairly represented in both soils but with bacterial taxonomic affiliations. Sites like ACGT, hitherto poorly studied and understood, could be sources of novel bioresources.

Effects of anthropogenic activities on the microbial community diversity of Ologe Lagoon sediment in Lagos State, Nigeria.

The impact of pollution on the Ologe Lagoon was assessed by comparing physicochemical properties, hydrocarbon concentrations and microbial community structures of the sediments obtained from distinct sites of the lagoon. The locations were the human activity site (OLHAS), industrial-contaminated sites (OLICS) and relatively undisturbed site (OLPS). The physicochemical properties, heavy metal concentrations and hydrocarbon profiles were determined using standard methods. The microbial community structures of the sediments were determined using shotgun next-generation sequencing (NGS), taxonomic profiling was performed using centrifuge and statistical analysis was done using statistical analysis for metagenomics profile (STAMP) and Microsoft Excel. The result showed acidic pH across all sampling points, while the nitrogen content at OLPS was low (7.44 ± 0.085 mg/L) as compared with OLHAS (44.380 ± 0.962 mg/L) and OLICS (59.485 ± 0.827 mg/L). The levels of the cadmium, lead and nickel in the three sites were above the regulatory limits. The gas chromatography flame ionization detector (GC-FID) profile revealed hydrocarbon contaminations with nC14 tetradecane > alpha xylene > nC9 nonane > acenaphthylene more enriched at OLPS. Structurally, the sediments metagenomes consisted of 43 phyla,75 classes each, 165, 161, 166 orders, 986, 927 and 866 bacterial genera and 1476, 1129, 1327 species from OLHAS, OLICS and OLPS, respectively. The dominant phyla in the sediments were Proteobacteria, Firmicutes, Actinobacteria, and Chloroflexi. The principal component ordination (PCO) showed that OLPS microbial community had a total variance of 87.7% PCO1, setting it apart from OLHAS and OLICS. OLICS and OLHAS were separated by PCO2 accounting for 12.3% variation, and the most polluted site is the OLPS.

Depletion of hydrocarbons and concomitant shift in bacterial community structure of a diesel-spiked tropical agricultural soil.

Bacterial community of a diesel-spiked agricultural soil was monitored over a 42-day period using the metagenomic approach in order to gain insight into key phylotypes impacted by diesel contamination and be able to predict end point of bioattenuation. Soil physico-chemical parameters showed significant differences (P < 0.05) between the Polluted Soil (PS) and the Unpolluted control (US)across time points. After 21 days, the diesel content decreased by 27.39%, and at the end of 42 days, by 57.11%. Aromatics such as benzene, anthanthrene, propylbenzene, phenanthrenequinone, anthraquinone, and phenanthridine were degraded to non-detected levels within 42 days, while some medium range alkanes and polyaromatics such as acenaphthylene, naphthalene, and anthracene showed significant levels of degradation. After 21 days (LASTD21), there was a massive enrichment of the phylum Proteobacteria (72.94%), a slight decrease in the abundance of phylum Actinobacteriota (12.74%), and > 500% decrease in the abundance of the phylum Acidobacteriodota (5.26%). Day 42 (LASTD42) saw establishment of the dominance of the Proteobacteria (34.95%), Actinobacteriota, (21.71%), and Firmicutes (32.14%), and decimation of phyla such as Gemmatimonadota, Planctomycetota, and Verrucromicrobiota which play important roles in the cycling of elements and soil health. Principal component analysis showed that in PS moisture contents, phosphorus, nitrogen, organic carbon, had greater impacts on the community structure in LASTD21, while acidity, potassium, sodium, calcium and magnesium impacted the control sample. Recovery time of the soil based on the residual hydrocarbons at Day 42 was estimated to be 229.112 d. Thus, additional biostimulation may be required to achieve cleanup within one growing season.