Microbial communities involving dehalogenating bacteria assist in bioremediation of areas contaminated with halocarbons. To understand molecular interactions between dehalogenating bacteria, we co-cultured Sulfurospirillum multivorans, dechlorinating tetrachloroethene (PCE) to cis−1,2-dichloroethene (cDCE), and Dehalococcoides mccartyi strains BTF08 or 195, dehalogenating PCE to ethene. The co-cultures were cultivated with lactate as electron donor. In co-cultures, the bacterial cells formed aggregates and D. mccartyi established an unusual, barrel-like morphology. An extracellular matrix surrounding bacterial cells in the aggregates enhanced cell-to-cell contact. PCE was dehalogenated to ethene at least three times faster in the co-culture. The dehalogenation was carried out via PceA of S. multivorans, and PteA (a recently described PCE dehalogenase) and VcrA of D. mccartyi BTF08, as supported by protein abundance. The co-culture was not dependent on exogenous hydrogen and acetate, suggesting a syntrophic relationship in which the obligate hydrogen consumer D. mccartyi consumes hydrogen and acetate produced by S. multivorans. The cobamide cofactor of the reductive dehalogenase—mandatory for D. mccartyi—was also produced by S. multivorans. D. mccartyi strain 195 dechlorinated cDCE in the presence of norpseudo-B₁₂ produced by S. multivorans, but D. mccartyi strain BTF08 depended on an exogenous lower cobamide ligand. This observation is important for bioremediation, since cofactor supply in the environment might be a limiting factor for PCE dehalogenation to ethene, described for D. mccartyi exclusively. The findings from this co-culture give new insights into aggregate formation and the physiology of D. mccartyi within a bacterial community.

涉及脱卤细菌的微生物群落有助于对被卤化碳污染的区域进行生物修复。为了解脱卤细菌之间的分子相互作用，我们共培养了将四氯乙烯 (PCE) 脱氯为顺式−1,2-二氯乙烯 ( c DCE)的Sulfurospirillum multivorans ，以及将 PCE 脱卤为乙烯的Dehalococcoides mccartyi菌株 BTF08 或 195。以乳酸盐作为电子供体培养共培养物。在共培养中，细菌细胞形成聚集体和D. mccartyi建立了一种不寻常的桶状形态。聚集体中细菌细胞周围的细胞外基质增强了细胞间的接触。在共培养中，PCE 脱卤为乙烯的速度至少快三倍。脱卤是通过S. multivorans的 PceA 和 PteA（最近描述的 PCE 脱卤酶）和D. mccartyi BTF08 的 VcrA 进行的，并得到蛋白质丰度的支持。共培养不依赖于外源性氢气和乙酸盐，表明一种互养关系，其中专性氢气消费者D. mccartyi消耗S. multivorans产生的氢气和乙酸盐。还原脱卤素酶的钴酰胺辅助因子——对D. mccartyi是必需的——也是由S. multivorans生产的。D. mccartyi菌株 195在由S. multivorans产生的 norpseudo -B _{12存在的情况下脱氯}c DCE ，但D. mccartyi菌株 BTF08 依赖于外源低级钴酰胺配体。这一观察对于生物修复很重要，因为环境中的辅助因子供应可能是 PCE 脱卤为乙烯的限制因素，专门针对D. mccartyi进行了描述。这种共培养的发现为细菌群落中D. mccartyi的聚集体形成和生理学提供了新的见解。