Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, 43403, USA.
Acta Biotheor. 2021 Sep;69(3):343-358. doi: 10.1007/s10441-020-09402-y. Epub 2020 Dec 7.
Bacteria are divided primarily into monoderms (with one cell membrane, and usually Gram-positive, due to a thick peptidoglycan layer) and diderms (with two cell membranes, and mostly Gram-negative, due to a thin peptidoglycan layer sandwiched between the two membranes). Photosynthetic species are spread among the taxonomic groups, some having type I reaction centers (RCI in monoderm phylum Firmicutes; and diderm phyla Acidobacteria and Chlorobi), others with type II reaction centers (RCII in monoderm phylum Chloroflexi; and diderm taxa Gemmatimonadetes, and alpha-, beta-, and gamma-Proteobacteria), and some containing both (RCI and RCII, only in diderm phylum Cyanobacteria). In most bacterial phylograms, photosystem types and diderm taxa are polyphyletic. A more parsimonious arrangement, which is supported by photosystem evolution, as well as additional sets of molecular characters, suggests that endosymbiotic events resulted in the formation of the diderms. In the model presented, monoderms readily form a monophyletic group, while diderms are produced by at least two endosymbiotic events, followed by additional evolutionary changes.
细菌主要分为单胞菌（有一层细胞膜，通常为革兰氏阳性，因为有一层厚厚的肽聚糖层）和双胞菌（有两层细胞膜，大多数为革兰氏阴性，因为有一层薄薄的肽聚糖层夹在两层膜之间）。光合物种分布在各个分类群中，有些具有 I 型反应中心（在单胞菌门Firmicutes 的 RCI；双胞菌门 Acidobacteria 和 Chlorobi），有些具有 II 型反应中心（在单胞菌门 Chloroflexi 的 RCII；双胞菌门 Gemmatimonadetes，以及 alpha、beta 和 gamma-Proteobacteria），有些则同时具有两者（RCI 和 RCII，仅在双胞菌门 Cyanobacteria 中）。在大多数细菌系统发育树中，光合系统类型和双胞菌分类群是多系的。一个更简约的排列，它得到了光合系统进化以及其他分子特征的支持，表明内共生事件导致了双胞菌的形成。在提出的模型中，单胞菌很容易形成一个单系群，而双胞菌则是至少两次内共生事件产生的，随后发生了额外的进化变化。
