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Xiao Y, Chen X, Lu H, Jiang T, Wang Y, Liang L, Dobretsov S, Huang Y. Regulation of quorum sensing activities by the stringent response gene rsh in sphingomonads is species-specific and culture condition dependent. Front Microbiol 2024; 15:1368499. [PMID: 38638897 PMCID: PMC11024222 DOI: 10.3389/fmicb.2024.1368499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 03/20/2024] [Indexed: 04/20/2024] Open
Abstract
Stringent response and quorum sensing (QS) are two essential mechanisms that control bacterial global metabolism for better survival. Sphingomonads are a clade of bacteria that survive successfully in diverse ecosystems. In silico survey indicated that 36 out of 79 investigated sphingomonads strains contained more than one luxI homolog, the gene responsible for the biosynthesis of QS signal acyl homoserine lactones (AHLs). Investigation of the regulatory effects of the stringent response gene rsh on QS related bioactivities were carried out using rsh mutants of Sphingobium japonicum UT26 and Sphingobium sp. SYK-6, both had three luxI homologs. Results indicated that deletion of rsh upregulated the overall production of AHLs and extracellular polymeric substances (EPS) in both UT26 and SYK-6 in rich medium, but affected expressions of these luxI/luxR homologs in different ways. In the poor medium (1% LB), rsh mutant of SYK-6 significantly lost AHLs production in broth cultivation but not in biofilm cultivation. The regulatory effects of rsh on QS activities were growth phase dependent in UT26 and culture condition dependent in SYK-6. Our results demonstrated the negative regulatory effect of rsh on QS activities in sphingomonads, which were very different from the positive effect found in sphingomonads containing only one luxI/R circuit. This study extends the current knowledge on the intricate networks between stringent response and QS system in sphingomonads, which would help to understand their survival advantage.
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Affiliation(s)
- Yue Xiao
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Xin Chen
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Hang Lu
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Tingting Jiang
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Yichun Wang
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Luyi Liang
- National Demonstration Center for Experimental Environment and Resources Education, Zhejiang University, Hangzhou, China
| | - Sergey Dobretsov
- UNESCO Chair, Department of Marine Science and Fisheries, College of Agricultural and Marine Sciences, Sultan Qaboos University, Muscat, Oman
| | - Yili Huang
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
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Lu Z, Li W, Xin Y, Huang Y. The stringent response gene rsh plays multiple roles in Novosphingobium pentaromativorans US6-1's accommodation to different environmental pollutants: Phenanthrene, copper and nZVI. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 323:121315. [PMID: 36813102 DOI: 10.1016/j.envpol.2023.121315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/27/2023] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
The rsh based stringent response system is widely employed by bacteria to cope with environmental stresses. However, how does the stringent response involve in bacterial accommodation to environmental pollutant is largely unexplored. In this study, to comprehensively understand the roles of rsh in Novosphingobium pentaromativorans US6-1's metabolism and accommodation to different pollutants, three distinct pollutants, phenanthrene, copper and nanoparticulated zero valent iron (nZVI) were selected as exposure substances. Results indicated that rsh played important roles in US6-1's multiplication and metabolism, including survival rate at stationary phase, amino acid and nucleotide metabolism, extracellular polymeric substance (EPS) production, redox homeostasis, etc. The deletion of rsh affected phenanthrene removal rates through regulating the multiplication of US6-1 and increasing the expression of degradation related genes. The rsh mutant showed higher resistance to copper than the wild type, largely due to higher EPS production and enhanced expression of copper resistance related genes. Finally, the rsh based stringent response helped maintain the redox homeostasis when US6-1 confronted nZVI particles that exerted oxidative stress, thereby improving the survival rate. Overall, this study provides firsthand data that rsh plays multiple roles in US6-1's accommodation to environmental pollutants. The stringent response system could be a powerful tool for environmental scientists and engineers to harness bacterial activities for bioremediation purposes.
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Affiliation(s)
- Zejia Lu
- Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Weiqi Li
- Department of Resources Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Yiding Xin
- Department of Resources Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Yili Huang
- Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China.
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Preliminary characterization and phylogeny of sphingomonads occurring on Stone and Pome Fruit Trees in Northern Iran. Biologia (Bratisl) 2021. [DOI: 10.1007/s11756-021-00895-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Huang Y, Lu Z, Jiang T, Zeng Y, Zeng Y, Chen B. Oxygen availability affects the synthesis of quorum sensing signal in the facultative anaerobe Novosphingobium pentaromativorans US6-1. Appl Microbiol Biotechnol 2021; 105:1191-1201. [PMID: 33439275 DOI: 10.1007/s00253-021-11089-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 12/13/2020] [Accepted: 01/03/2021] [Indexed: 01/01/2023]
Abstract
Bacterial populations rely on quorum sensing (QS) to coordinate their behaviors and are often challenged by the fluctuation in oxygen concentrations in their habitats. Oxygen is a crucial factor that affects bacterial metabolism in multiple ways. However, little is known about whether and how oxygen availability affects QS activities. To fill this gap, we used the facultative anaerobe Novosphingobium pentaromativorans US6-1 as a model system, and observed that the QS signal acyl homoserine-lactones (AHLs) were produced only in anoxic environments, such as biofilm, or liquid medium that initially contained less than 2 mg/L dissolved oxygen, but not in highly oxic environments. Comparative transcriptome analysis revealed that oxygen availability significantly affected the physiological activities in US6-1, including fatty acid metabolism, oxidative phosphorylation, citrate cycle, QS activities, and flagellar assembly. The absence of AHLs in the oxic culture was not due to degradation, but to the very low expression of the AHL synthase gene novI. High concentration of NADH during the middle log phase under static cultivation may be a trigger for AHL synthesis. This is the first report that production of AHLs is coupled with anoxic metabolism in a facultative anaerobe, which extends our knowledge on factors affecting bacterial QS occurrence. KEY POINTS: • AHL production is anoxic cultivation related. • Oxygen availability affects AHL synthesis by influencing novI expression. • Oxygen availability changes many metabolism activities including NADH production.
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Affiliation(s)
- Yili Huang
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Bulding NongB, Hangzhou, 310058, China.
| | - Zejia Lu
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Bulding NongB, Hangzhou, 310058, China
| | - Tingting Jiang
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Bulding NongB, Hangzhou, 310058, China
| | - Yonghui Zeng
- Department of Environmental Science, Aarhus University, 4000, Roskilde, Denmark
| | - Yanhua Zeng
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Bulding NongB, Hangzhou, 310058, China
| | - Baoliang Chen
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Department of Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Bulding NongB, Hangzhou, 310058, China
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Feng GD, Zhang XJ, Yang SZ, Li AZ, Yao Q, Zhu H. Transfer of Sphingorhabdus marina, Sphingorhabdus litoris, Sphingorhabdus flavimaris and Sphingorhabdus pacifica corrig. into the novel genus Parasphingorhabdus gen. nov. and Sphingopyxis baekryungensis into the novel genus Novosphingopyxis gen. nov. within the family Sphingomonadaceae. Int J Syst Evol Microbiol 2020; 70:2147-2154. [PMID: 32011975 DOI: 10.1099/ijsem.0.004033] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During a phylogenetic analysis of Sphingorhabdus and its closely related genera in the family Sphingomonadaceae, we found that the genus Sphingorhabdus and the species Sphingopyxis baekryungensis might not be properly assigned in the taxonomy. Phylogenetic, phenotypic and chemotaxonomic characterizations clearly showed that the genus Sphingorhabdus should be reclassified into two genera (Clade I and Clade II), for which the original genus name, Sphingorhabdus, is proposed to be retained only for Clade I, and a new genus named as Parasphingorhabdus gen. nov. is proposed for Clade II with four new combinations: Parasphingorhabdus marina comb. nov., Parasphingorhabdus litoris comb. nov., Parasphingorhabdus flavimaris comb. nov. and Parasphingorhabdus pacifica comb. nov. Moreover, Sphingopyxis baekryungensis should represent a novel genus in the family Sphingomonadaceae, for which the name Novosphingopyxis gen. nov. is proposed, with a combination of Novosphingopyxis baekryungensis comb. nov. The study provides a new insight into the taxonomy of closely related genera in the family Sphingomonadaceae.
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Affiliation(s)
- Guang-Da Feng
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Microbial Culture Collection Center (GDMCC), Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China
| | - Xian-Jiao Zhang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Microbial Culture Collection Center (GDMCC), Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China
| | - Song-Zhen Yang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Microbial Culture Collection Center (GDMCC), Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China
| | - An-Zhang Li
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Microbial Culture Collection Center (GDMCC), Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China
| | - Qing Yao
- College of Horticulture, South China Agricultural University, Guangzhou 510642, PR China
| | - Honghui Zhu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Microbial Culture Collection Center (GDMCC), Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China
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Transcriptome Analysis of Novosphingobium pentaromativorans US6-1 Reveals the Rsh Regulon and Potential Molecular Mechanisms of N-acyl-l-homoserine Lactone Accumulation. Int J Mol Sci 2018; 19:ijms19092631. [PMID: 30189641 PMCID: PMC6163740 DOI: 10.3390/ijms19092631] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 08/27/2018] [Accepted: 09/02/2018] [Indexed: 11/17/2022] Open
Abstract
In most bacteria, a bifunctional Rsh responsible for (p)ppGpp metabolism is the key player in stringent response. To date, no transcriptome-wide study has been conducted to investigate the Rsh regulon, and the molecular mechanism of how Rsh affects the accumulation of N-acyl-l-homoserine lactone (AHL) remains unknown in sphingomonads. In this study, we identified an rshUS6–1 gene by sequence analysis in Novosphingobium pentaromativorans US6-1, a member of the sphingomonads. RNA-seq was used to determine transcription profiles of the wild type and the ppGpp-deficient rshUS6–1 deletion mutant (∆rsh). There were 1540 genes in the RshUS6–1 regulon, including those involved in common traits of sphingomonads such as exopolysaccharide biosynthesis. Furthermore, both RNA-seq and quantitative real-time polymerase chain reaction (qRT-PCR) showed essential genes for AHL production (novI and novR) were positively regulated by RshUS6–1 during the exponential growth phase. A degradation experiment indicated the reason for the AHL absence in ∆rsh was unrelated to the AHL degradation. According to RNA-seq, we proposed σE, DksA, Lon protease and RNA degradation enzymes might be involved in the RshUS6–1-dependent expression of novI and novR. Here, we report the first transcriptome-wide analysis of the Rsh regulon in sphingomonads and investigate the potential mechanisms regulating AHL accumulation, which is an important step towards understanding the regulatory system of stringent response in sphingomonads.
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