Phosphorus strategy alters mechanism of microbial stress caused by soil arsenic contamination

Phosphorus and arsenic, as elements of the same main group, co-existing affected soil microbial-mediated transformations of arsenic and phosphorus, thereby altering arsenic toxicity and phosphorus availability. Understanding the effects of changes in concentrations on microbial arsenic metabolism and phosphorus cycling is important for controlling arsenic pollution. In this study, we investigated the microbial communities and functions of arsenic-metabolism and phosphorus-cycling microorganisms in soils surrounding gold mines with moderate and very high available phosphorus concentrations, and high, moderate and low arsenic concentrations. The results showed that in soils with high available phosphorus concentrations, the cooperation between microorganisms combining arsenic-metabolism and phosphorus-cycling was closer. Key microorganisms contribute significantly to both arsenic detoxification and phosphorus solubilization functions. In soils with low available phosphorus concentrations, there was a positive correlation between microbial arsenic metabolism genes abundance and organic phosphorus mineralization phnI abundance. These genes were also positively correlated with arsenic concentration. This suggests that microbial phosphorus activation functions may be an adaptive strategy in arsenic-contaminated or phosphorus-limited soils. Therefore, this study concludes that microorganisms may adapt to arsenic stress through the strategy of mineralizing organic phosphorus. Strategies to increase phosphorus concentrations may also promote microbial cooperation in arsenic-contaminated soils.