Department of Microbiology, Southern Illinois University, Carbondale, IL 62901, USA.
Photosynth Res. 2010 Jun;104(2-3):103-11. doi: 10.1007/s11120-009-9516-1. Epub 2010 Jan 22.
Heliobacteria are a recently discovered group of anoxygenic phototrophic bacteria, first described in 1983. Heliobacteria contain bacteriochlorophyll g, a pigment unique to species of this group, and synthesize the simplest photosynthetic complexes of all known phototrophs. Also, unlike all other phototrophs, heliobacteria lack a mechanism for autotrophy and produce endospores. Four genera of heliobacteria containing a total of 10 species are known. Species of the genera Heliobacterium, Heliobacillus, and Heliophilum grow best at neutral pH, whereas species of Heliorestis are alkaliphilic. Heliobacterium, Heliobacillus, and Heliophilum species form one phylogenetic clade of heliobacteria, while Heliorestis species form a second within the phylum Firmicutes of the domain Bacteria. Heliobacteria have a unique ecology, being primarily terrestrial rather than aquatic phototrophs, and may have evolved a mutualistic relationship with plants, in particular, rice plants. The genome sequence of the thermophile Heliobacterium modesticaldum supports the hypothesis that heliobacteria are "minimalist phototrophs" and that they may have played a key role in the evolution of phototrophic bacteria.
产甲烷菌是一类新近发现的厌氧光合细菌,于 1983 年首次被描述。产甲烷菌含有细菌叶绿素 g,这是该类群特有的一种色素,并合成所有已知光合生物中最简单的光合复合物。此外,与所有其他光合生物不同,产甲烷菌缺乏自养机制并产生内生孢子。目前已知有四个属共 10 种产甲烷菌。属的种属 Heliobacterium、Heliobacillus 和 Heliophilum 最适合在中性 pH 值下生长,而属 Heliorestis 的种则是嗜碱性的。Heliobacterium、Heliobacillus 和 Heliophilum 种形成产甲烷菌的一个系统发育分支,而 Heliorestis 种则在细菌域的厚壁菌门Firmicutes 内形成第二个分支。产甲烷菌具有独特的生态,主要是陆地而不是水生光合生物,可能与植物,特别是水稻植物,形成了共生关系。嗜热菌 Heliobacterium modesticaldum 的基因组序列支持了产甲烷菌是“极简主义光合生物”的假设,并且它们可能在光合细菌的进化中发挥了关键作用。