Soil Microbial Communities Altered by Titanium Ions in Different Agroecosystems of Pitaya and Grape

Soil health implications of some d-block metals in selected agricultural soils in Southeast Nigeria

Soil fertility, soil health and environmental management through the estimation of background concentration of potentially toxic elements is required for environmental safety. This study aims at investigating the concentration, fertility and potential health risks of some d-block metals (Ti, V, Fe, Mn, and Mo) in some agricultural soils, and establishes the relationship between the metals and some soil properties. Eight elevation ranges resulted from the digital elevation models of the study area; two in Ishibori (NG1, NG2), three each in Agoi-Ibami (CG1, CG2, CG3) and Mfamosing (SG1, SG2 and SG3). One soil profile pit was sunk along each of the elevations. Thirty-five composite soil samples were collected at 0-30, 30-60, 60-90, 90-120, 120-150, 150-180 and 180-200 cm depending on soil depth. Only the profile means of Mn (660.82 ± 612.89 mg/kg) and Mo (2.61 ± 0.73 mg/kg) exceeded permissible concentrations and would pose threats to the environment. Also, the concentrations of the d-block metals exceeded permissible values in Ishibori making them prone to toxicity. The metals were irregularly distributed with depth; however, Mn and Fe were concentrated in the subsurface soils. Clay and sand contents correlated positively and negatively, respectively with all the d-block metals at p < 0.05. The linear model was more efficient in estimating V and Mo via soil properties with adjusted R2 of 33 - 67% for the metals. In conclusion, agricultural activities and geology may influence the accumulation of d-block metals, hence the call for environmental monitoring to curtail metals' assimilation by crops. HIGHLIGHTS: • Mn and Mo threaten the environment the most. • Soils in the Southern Guinea Savannah are most prone to d-block metals contamination. • BD, pH, Mg, and CEC are the best predictors of d-block metals in the soils. • The linear model was best performing in the estimation of V and Mo, respectively.

Deciphering the distribution of microbial communities and potential pathogens in the household dust

The reliance of modern society on indoor environments increasing has made them crucial sites for human exposure to microbes. Extensive research has identified ecological drivers that influence indoor microbial assemblages. However, few studies have examined the dispersion of microbes in different locations of identical indoor environments. In this study, we employed PacBio Sequel full-length amplicon sequencing to examine the distribution of microbes at distinct locations in a single home and to identify the potential pathogens and microbial functions. Microbial communities differed considerably among the indoor sampling sites (P < 0.05). In addition, bacterial diversity was influenced by human activities and contact with the external environment at different sites, whereas fungal diversity did not significantly differ among the sites. Potential pathogens, including bacteria and fungi, were significantly enriched on the door handle (P < 0.05), suggesting that door handles may be hotpots for potential pathogens in the household. A high proportion of fungal allergens (34.37 %-56.50 %), which can cause skin diseases and asthma, were observed. Co-occurrence network analysis revealed the essential ecological role of microbial interactions in the development of a healthy immune system. Overall, we revealed the differences in microbial communities at different sampling sites within a single indoor environment, highlighting the distribution of potential pathogens and ecological functions of microbes, and providing a new perspective and information for assessing indoor health from a microbiological viewpoint.

Soil Mineral Composition and Salinity Are the Main Factors Regulating the Bacterial Community Associated with the Roots of Coastal Sand Dune Halophytes

Soil salinity and mineral deficiency are major problems in agriculture. Many studies have reported that plant-associated microbiota, particularly rhizosphere and root microbiota, play a crucial role in tolerance against salinity and mineral deficiency. Nevertheless, there are still many unknown parts of plant–microbe interaction, especially regarding their role in halophyte adaptation to coastal ecosystems. Here, we report the bacterial community associated with the roots of coastal sand dune halophytes Spinifex littoreus and Calotropis gigantea, and the soil properties that affect their composition. Strong correlations were observed between root bacterial diversity and soil mineral composition, especially with soil Calcium (Ca), Titanium (Ti), Cuprum (Cu), and Zinc (Zn) content. Soil Ti and Zn content showed a positive correlation with bacterial diversity, while soil Ca and Cu had a negative effect on bacterial diversity. A strong correlation was also found between the abundance of several bacterial species with soil salinity and mineral content, suggesting that some bacteria are responsive to changes in soil salinity and mineral content. Some of the identified bacteria, such as Bacillus idriensis and Kibdelosporangium aridum, are known to have growth-promoting effects on plants. Together, the findings of this work provided valuable information regarding bacterial communities associated with the roots of sand dune halophytes and their interactions with soil properties. Furthermore, we also identified several bacterial species that might be involved in tolerance against stresses. Further work will be focused on isolation and transplantation of these potential microbes, to validate their role in plant tolerance against stresses, not only in their native hosts but also in crops.