这个词是什么意思？
A genus of gram-negative, ovoid to rod-shaped bacteria that is phototrophic. All species use ammonia as a nitrogen source. Some strains are found only in sulfide-containing freshwater habitats exposed to light while others may occur in marine, estuarine, and freshwater environments.
中文名称索引；定义为 MeSH 英文原文，尚未逐条译审。MESH:D002844 · MeSH 2026。
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