Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan.
BMC Microbiol. 2024 Oct 9;24(1):396. doi: 10.1186/s12866-024-03562-4.
Arsenic (As) metabolism by soil microorganisms has an impact on As geochemical cycling in paddy soils, which in turn affects As uptake in rice. However, little is known about the key microorganisms involved in this process in Japanese paddy soil.
Total RNA was extracted from Japanese paddy soils with different levels of dissolved As under flooded conditions, and the transcription of As metabolic genes (arrA, ttrA and arsM) was analyzed via a metatranscriptomic approach. The results showed that ttrA was the predominant respiratory arsenate reductase gene transcribed in these soils rather than arrA, suggesting that ttrA contributes to the reductive dissolution of As. The predominant taxa expressing ttrA differed among soils but were mostly associated with genera known for their iron- and/or sulfate-reduction activity. In addition, a wide variety of microorganisms expressed and upregulated arsM approximately 5.0- to 13.2-fold at 9 d compared with 3 d of incubation under flooded conditions in flasks.
Our results support the involvement of microbial activity in the geochemical cycling of As in Japanese paddy soils and suggest that ttrA may be one of the key genes involved in the formation of arsenite, an inorganic species taken up by rice.
土壤微生物对砷（As）的代谢作用会影响稻田中 As 的地球化学循环，进而影响水稻对 As 的吸收。然而，对于日本稻田中参与这一过程的关键微生物知之甚少。
在淹水条件下，从具有不同溶解态 As 水平的日本稻田中提取总 RNA，并通过宏转录组学方法分析 As 代谢基因（arrA、ttrA 和 arsM）的转录。结果表明，ttrA 是这些土壤中主要转录的呼吸性砷酸盐还原酶基因，而不是 arrA，这表明 ttrA 有助于 As 的还原溶解。在不同土壤中表达 ttrA 的主要分类群不同，但大多与已知具有铁和/或硫酸盐还原活性的属有关。此外，在瓶中淹水培养 9 天与 3 天时相比，大约有 5.0-13.2 倍的各种微生物表达和上调 arsM。
我们的结果支持微生物活性参与日本稻田中 As 的地球化学循环，并表明 ttrA 可能是参与形成砷酸盐的关键基因之一，砷酸盐是水稻吸收的一种无机物种。
