antimony and arsenic contanmination in in rice paddies during different stages of growth Raw sequence reads. antimony and arsenic contanmination in in rice paddies during different stages of growth

Rice is more vulnerable to arsenic (As) and antimony (Sb) contamination than other cereals due to the special cultivation methods, during which irrigation conditions are adjusted depending upon the growth stages. The alternation between flooded and drained conditions changes the watering conditions and thus the ability of microorganisms to alter the mobility and bioavailability of Sb and As, which influences their uptake by rice. In comparison to extensive studies of As microbiology, our understanding of Sb biotransformation is very limited. In addition, information about the effects of the changes in irrigation during different stages of rice cultivation on the microbial response to As and Sb is lacking. In this study, bacterial responses to As and Sb contamination in rice fields were investigated during two different stages of rice growth: the vegetative stage, during which the fields were flooded, and the ripening stage, during which the fields were drained. The changes in the irrigation conditions caused a variation in geochemical parameters, especially in the As- and Sb-extractable fractions. As and Sb were more mobile and bioaccessible during the vegetative stage than those in the ripening stage. The bacterial communities also formed two clusters that corresponded to the two rice growth stages. The environment-microbe interactions were revealed by various statistical tools. One of the notable findings is that Sb- and As-related parameters exerted more influence during the vegetative stage than those of the ripening stage derived from the co-occurrence network analysis. Furthermore, a detailed random forest (RF) analysis indicated that the individual bacterial taxa may also respond differently to contaminant fractions during the two growth stages. Notably, individual bacterial taxa were implicated in Sb and As biotransformation based on statistical analyses. For example, Geobacter and Clostridiaceae may have the potential to reduce As(V) or even Sb(V), which may result in the greater mobility and bioavailability of As and Sb during the vegetative stage than that during the ripening stage.