Université de Lorraine, INRAE, UMR1136, Interactions Arbres-Microorganismes, F-54280 Champenoux, France.
INRAE, UR1138, Biogéochimie des écosystèmes forestiers, F-54280 Champenoux, France.
FEMS Microbiol Ecol. 2020 Dec 29;97(1). doi: 10.1093/femsec/fiaa232.
The exact molecular mechanisms as well as the genes involved in the mineral weathering (MW) process by bacteria remain poorly characterized. To date, a single type of glucose dehydrogenase (GDH) depending on a particular co-factor named pyrroloquinoline quinone (PQQ) is known. These enzymes allow the production of gluconic acid through the oxidation of glucose. However, it remains to be determined how bacteria missing PQQ-dependent GDH and/or the related pqq biogenesis genes weather minerals. In this study, we considered the very effective mineral weathering bacterial strain PMB3(1) of Collimonas pratensis. Genome analysis revealed that it does not possess the PQQ-based system. The use of random mutagenesis, gene complementation and functional assays allowed us to identify mutants impacted in their ability to weather mineral. Among them, three mutants were strongly altered on their acidification and biotite weathering abilities (58% to 75% of reduction compared to WT) and did not produce gluconic acid. The characterization of the genomic regions allowed noticeably to the identification of a Glucose/Methanol/Choline oxidoreductase. This region appeared very conserved among collimonads and related genera. This study represents the first demonstration of the implication of a PQQ-independent GDH in the mineral weathering process and explains how Collimonas weather minerals.
确切的分子机制以及涉及细菌的矿物风化（MW）过程的基因仍未得到充分描述。迄今为止，仅有一种依赖于特定辅因子吡咯喹啉醌（PQQ）的葡萄糖脱氢酶（GDH）被人们所了解。这些酶通过氧化葡萄糖来生产葡萄糖酸。然而，目前仍不清楚缺少 PQQ 依赖型 GDH 和/或相关 pqq 生物发生基因的细菌如何风化矿物质。在本研究中，我们考虑了 Collimonas pratensis 的非常有效的矿物风化细菌菌株 PMB3(1)。基因组分析表明，它不具有基于 PQQ 的系统。使用随机诱变、基因互补和功能测定，我们能够鉴定出影响其风化矿物质能力的突变体。其中，三个突变体在酸化和黑云母风化能力方面受到强烈影响（与 WT 相比降低了 58%至 75%），并且不产生葡萄糖酸。对基因组区域的特征分析显著鉴定了一种葡萄糖/甲醇/胆碱氧化还原酶。该区域在 collimonads 和相关属中非常保守。本研究首次证明了 PQQ 独立型 GDH 参与矿物风化过程，并解释了 Collimonas 如何风化矿物质。
