解糖微小寄生菌的研究进展

Research progress of Saccharibacteria:a review

候选门级辐射类群(candidate phyla radiation,CPR)所包含的细菌种类约占已知细菌种类总数的1/4,然而该类细菌中只有解糖微小寄生菌(Saccharibacteria,又名TM7)的少数菌株被成功分离培养.研究发现,解糖微小寄生菌具有许多独特的生物学性状:该类细菌需要寄生在宿主细菌表面生长,这是一种全新的"细菌-细菌"寄生生存方式;细菌尺寸及基因组均较小,缺乏代谢相关基因,不能合成氨基酸和维生素;对宿主细菌表现出杀伤作用或保护其躲避免疫系统的攻击.此外,解糖微小寄生菌与牙周病等疾病存在紧密的联系.同时,宏基因组学研究表明,其他CPR细菌与解糖微小寄生菌具有相似的生物学特性.本文通过介绍解糖微小寄生菌的研究概况、形态特征、生理特性、基因特点以及与疾病的相关关系,以期对目前研究进展有更全面的了解,为未来解糖微小寄生菌及CPR细菌的研究提供参考,这对于发现新物种、发掘新基因、改进疾病的预防和治疗方式以及研究细菌的进化有着重要的生物学意义和社会意义.

Candidate phyla radiation(CPR)contains about one-fourth of all the known bacteria.However,only a few strains of bacteria from the Saccharibacteria phylum(also known as TM7)have been successfully isolated among CPR.Studies have found that Saccharibacteria have many unique biological characteristics.This type of bacteria live on the surface of the host bacteria,which is a novel“bacteriabacteria”parasitic lifestyle;the size and genome of the bacteria are small,thus they cannot synthesize amino acids and vitamins due to lacking metabolism-related genes;when interacted with the host bacteria,they could kill their host bacteria or protect them from the immune system.Besides,Saccharibacteria are closely related to diseases such as periodontal disease.Meanwhile,metagenomics studies have shown that other CPR bacteria may have similar biological characteristics to Saccharibacteria.This review introduces the related research,morphological characteristics,physiological characteristics,genetic characteristics,and the relationship between Saccharibacteria and diseases,and tries to update a more comprehensive understanding of the current research progress and to inspire the future studies of Saccharibacteria and CPR bacteria,which could reveal the biological and social importance in terms of discovering new species and genes,improving disease prevention and treatment and understanding the evolution of bacteria.