Bacteria of the SAR202 clade, within the phylum Chloroflexota, are ubiquitously distributed in the ocean but have not yet been cultivated in the lab. It has been proposed that ancient expansions of catabolic enzyme paralogs broadened the spectrum of organic compounds that SAR202 bacteria could oxidize, leading to transformations of the Earth’s carbon cycle. Here, we report the successful cultivation of SAR202 bacteria from surface seawater using dilution-to-extinction culturing. The growth of these strains is very slow (0.18–0.24 day⁻¹) and is inhibited by exposure to light. The genomes, of ca. 3.08 Mbp, encode archaella (archaeal motility structures) and multiple sets of enzyme paralogs, including 80 genes coding for enolase superfamily enzymes and 44 genes encoding NAD(P)-dependent dehydrogenases. We propose that these enzyme paralogs participate in multiple parallel pathways for non-phosphorylative catabolism of sugars and sugar acids. Indeed, we demonstrate that SAR202 strains can utilize several substrates that are metabolized through the predicted pathways, such as sugars ʟ-fucose and ʟ-rhamnose, as well as their lactone and acid forms.

SAR202 分支的细菌属于Chloroflexota门，广泛分布在海洋中，但尚未在实验室中培养。有人提出，古代分解代谢酶旁系同源物的扩展拓宽了 SAR202 细菌可以氧化的有机化合物的范围，从而导致地球碳循环的转变。在这里，我们报告了利用稀释至灭绝培养法从表层海水中成功培养 SAR202 细菌。这些菌株的生长非常缓慢（0.18-0.24 天^-1）并且受到光照的抑制。大约的基因组。3.08 Mbp，编码古菌（古菌运动结构）和多组酶旁系同源物，包括 80 个编码烯醇酶超家族酶的基因和 44 个编码 NAD(P) 依赖性脱氢酶的基因。我们认为这些酶旁系同源物参与糖和糖酸的非磷酸化分解代谢的多个平行途径。事实上，我们证明 SAR202 菌株可以利用通过预测途径代谢的多种底物，例如糖 ʟ-岩藻糖和 ʟ-鼠李糖，以及它们的内酯和酸形式。