在传统水体消毒技术刺激下,细菌会进入活的不可培养(viable but nonculturable,VBNC)状态来提高自身存活率。在撤去外部压力时,未被消毒技术完全去除的VBNC细菌可在水储存和分配期间发生一定程度的复苏,而这些复苏的细菌很可能进入人体...在传统水体消毒技术刺激下,细菌会进入活的不可培养(viable but nonculturable,VBNC)状态来提高自身存活率。在撤去外部压力时,未被消毒技术完全去除的VBNC细菌可在水储存和分配期间发生一定程度的复苏,而这些复苏的细菌很可能进入人体并导致严重疾病。然而,目前仍不清楚水体消毒过程中活的不可培养细菌的形成与复苏机制。该文通过检索了95篇相关文献并结合课题组在抗生素耐药菌方面的消毒控制和细菌休眠方面的研究进行了系统分析。首先,介绍了在不同水消毒技术下VBNC细菌的形成并阐述了其潜在的形成机制,其主要包括了严谨反应、能量代谢、一般应激反应系统和毒素-抗毒素系统。其次,介绍了VBNC致病菌复苏的风险和总结了13种复苏方法。该文还综述了自然复苏、复苏促进因子(Rpf)与自诱导剂复苏等3种复苏机制的不同。在修复了细胞损伤并恢复氧化还原平衡和代谢活性之后,VBNC细菌才能发生自然复苏。Rpf能够帮助VBNC细菌重塑细胞壁,这有助于VBNC细菌恢复可培养能力。自诱导剂-2能够促进微生物种群中的细胞间通讯并增加katG的表达来降低过氧化氢毒性,从而促进VBNC细菌的复苏。最后,对今后的研究方向进行了展望,介绍了微流控技术、稳定同位素示踪代谢活性分析方法、单细胞重水标记拉曼光谱方法和荧光能量共振转移技术等可以用于研究VBNC细菌复苏机制的前沿技术。该综述能为回答“多大剂量的消毒技术能够灭活VBNC细菌并避免其复苏”和“复苏的VBNC细菌生理特性是否都恢复到正常水平”等问题提供参考,为水处理过程中微生物安全性评估和制定更有效的消毒策略提供理论依据。展开更多
Background: Although BCG is the most widely administered vaccine in the world, there have never been as many cases of TB as there are now. Globally, more than 8.8 million people developed active TB and 1.4 million—ma...Background: Although BCG is the most widely administered vaccine in the world, there have never been as many cases of TB as there are now. Globally, more than 8.8 million people developed active TB and 1.4 million—many of them—died in 2010. It is estimated that half of pulmonary TB cases arise from latent Mtb infection, making the study of latency and reactivation of utmost importance. Methods: Widely administered BCG vaccines and a gene modified recombinant BCG (rBCG) strain, AERAS-422, were used as models to investigate the growth promoting function of resuscitation-promoting factors (Rpfs) in different bacilli culture phases. Different supernatant fractions were prepared by ultrafiltration, and the promoting function of each fraction containing secreted Rpf(s) was evaluated by growth curve monitoring and colony counting on 7H10 agar plates. Results: The promoting effect of culture supernatants was mainly associated with the high molecular weight fraction (>30 kDa), which stimulated bacterial growth, but did not extend the exponential phase of stimulated culture. Anti-RpfB antibody showed significant growth restriction of the tested cultures. When comparing rBCG cultures containing 7H9 medium, the 10 - 30 kDa fraction, or the >30 kDa fraction, only the >30 kDa fraction was displayed with down-regulation of the secretion of RpfC, D and E. In colony counting tests, the plates containing the >30 kDa fraction had total countable colony numbers 2 to 3 fold higher than the plates with the 10 - 30 kDa fraction, and colonies appeared one to two weeks earlier than on the regular plates. The potential applications of the prepared supernatant fractions containing RpfA and RpfB are discussed, which may include accelerating diagnosis of Mtb infection and future TB vaccine development.展开更多
有活力但不可培养(viable but non-culturable,VBNC)状态是细菌遭遇逆境时进入的一种特殊状态,该状态下的菌体在条件适宜时可复苏并恢复其致病性,被认为是细菌躲避不良环境的一种生存策略。VBNC状态菌体对人类医学和工农业生产具有巨大...有活力但不可培养(viable but non-culturable,VBNC)状态是细菌遭遇逆境时进入的一种特殊状态,该状态下的菌体在条件适宜时可复苏并恢复其致病性,被认为是细菌躲避不良环境的一种生存策略。VBNC状态菌体对人类医学和工农业生产具有巨大的潜在威胁,开展关于VBNC状态的检测及诱导、复苏及其机制研究可为减少或避免该状态细菌的危害提供理论基础。本文简要综述了细菌VBNC状态在诱导、复苏及致病性等方面的研究进展,并结合本实验室及国内外相关团队近年来在植物病原细菌VBNC状态研究中的结果,详细总结了VBNC状态细菌的形成和复苏机制,对植物病原细菌在环境胁迫下的存活机制、病害田间初侵染来源分析及VBNC状态菌体在病害循环中的作用等相关研究具有重要参考意义。展开更多
文摘在传统水体消毒技术刺激下,细菌会进入活的不可培养(viable but nonculturable,VBNC)状态来提高自身存活率。在撤去外部压力时,未被消毒技术完全去除的VBNC细菌可在水储存和分配期间发生一定程度的复苏,而这些复苏的细菌很可能进入人体并导致严重疾病。然而,目前仍不清楚水体消毒过程中活的不可培养细菌的形成与复苏机制。该文通过检索了95篇相关文献并结合课题组在抗生素耐药菌方面的消毒控制和细菌休眠方面的研究进行了系统分析。首先,介绍了在不同水消毒技术下VBNC细菌的形成并阐述了其潜在的形成机制,其主要包括了严谨反应、能量代谢、一般应激反应系统和毒素-抗毒素系统。其次,介绍了VBNC致病菌复苏的风险和总结了13种复苏方法。该文还综述了自然复苏、复苏促进因子(Rpf)与自诱导剂复苏等3种复苏机制的不同。在修复了细胞损伤并恢复氧化还原平衡和代谢活性之后,VBNC细菌才能发生自然复苏。Rpf能够帮助VBNC细菌重塑细胞壁,这有助于VBNC细菌恢复可培养能力。自诱导剂-2能够促进微生物种群中的细胞间通讯并增加katG的表达来降低过氧化氢毒性,从而促进VBNC细菌的复苏。最后,对今后的研究方向进行了展望,介绍了微流控技术、稳定同位素示踪代谢活性分析方法、单细胞重水标记拉曼光谱方法和荧光能量共振转移技术等可以用于研究VBNC细菌复苏机制的前沿技术。该综述能为回答“多大剂量的消毒技术能够灭活VBNC细菌并避免其复苏”和“复苏的VBNC细菌生理特性是否都恢复到正常水平”等问题提供参考,为水处理过程中微生物安全性评估和制定更有效的消毒策略提供理论依据。
文摘Background: Although BCG is the most widely administered vaccine in the world, there have never been as many cases of TB as there are now. Globally, more than 8.8 million people developed active TB and 1.4 million—many of them—died in 2010. It is estimated that half of pulmonary TB cases arise from latent Mtb infection, making the study of latency and reactivation of utmost importance. Methods: Widely administered BCG vaccines and a gene modified recombinant BCG (rBCG) strain, AERAS-422, were used as models to investigate the growth promoting function of resuscitation-promoting factors (Rpfs) in different bacilli culture phases. Different supernatant fractions were prepared by ultrafiltration, and the promoting function of each fraction containing secreted Rpf(s) was evaluated by growth curve monitoring and colony counting on 7H10 agar plates. Results: The promoting effect of culture supernatants was mainly associated with the high molecular weight fraction (>30 kDa), which stimulated bacterial growth, but did not extend the exponential phase of stimulated culture. Anti-RpfB antibody showed significant growth restriction of the tested cultures. When comparing rBCG cultures containing 7H9 medium, the 10 - 30 kDa fraction, or the >30 kDa fraction, only the >30 kDa fraction was displayed with down-regulation of the secretion of RpfC, D and E. In colony counting tests, the plates containing the >30 kDa fraction had total countable colony numbers 2 to 3 fold higher than the plates with the 10 - 30 kDa fraction, and colonies appeared one to two weeks earlier than on the regular plates. The potential applications of the prepared supernatant fractions containing RpfA and RpfB are discussed, which may include accelerating diagnosis of Mtb infection and future TB vaccine development.
文摘【目的】旨在阐明3个DSF/Rpfxoo信号系统成员RpfFxoo、RpfCxoo和RpfGxoo在水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)毒性表达中的功能。【方法】用标记置换法缺失突变rpfFxoo、rpfCxoo和rpfGxoo基因,测定突变体及其互补菌株的DSF(diffusible signal factor)信号分子产生、胞外多糖(EPS)产生及其对水稻的致病性。【结果】从野生型菌株PXO99A基因组中克隆了推测与DSF信号生成和传导有关的基因rpfFxoo、rpfCxoo和rpfGxoo,获得了相应的单基因或双基因缺失突变体。与PXO99A产生DSF相比,ΔrpfFxoo、ΔrpfF+Cxoo和ΔrpfF+Gxoo均不产生DSF,ΔrpfCxoo过量产生,ΔrpfGxoo产量降低;rpfFxoo、rpfCxoo和rpfGxoo可以分别互补Xoo和Xcc的相应基因突变体,恢复DSF产生表型。除ΔrpfFxoo的EPS产生无明显变化外,其余突变体的均显著减少。所有突变体对水稻的致病性均显著下降。【结论】RpfFxoo、RpfCxoo和RpfGxoo调控了Xoo的DSF信号生成、EPS产生和致病性。
文摘有活力但不可培养(viable but non-culturable,VBNC)状态是细菌遭遇逆境时进入的一种特殊状态,该状态下的菌体在条件适宜时可复苏并恢复其致病性,被认为是细菌躲避不良环境的一种生存策略。VBNC状态菌体对人类医学和工农业生产具有巨大的潜在威胁,开展关于VBNC状态的检测及诱导、复苏及其机制研究可为减少或避免该状态细菌的危害提供理论基础。本文简要综述了细菌VBNC状态在诱导、复苏及致病性等方面的研究进展,并结合本实验室及国内外相关团队近年来在植物病原细菌VBNC状态研究中的结果,详细总结了VBNC状态细菌的形成和复苏机制,对植物病原细菌在环境胁迫下的存活机制、病害田间初侵染来源分析及VBNC状态菌体在病害循环中的作用等相关研究具有重要参考意义。
