Stressed out: Bacterial response to high salinity using compatible solute biosynthesis and uptake systems, lessons from Vibrionaceae

Zeng

et al. 2021

Biology

To investigate the diversity and structure of soil bacterial and fungal communities in saline soils, soil samples with three increasing salinity levels (S1, S2 and S3) were collected from a maize field in Yanqi, Xinjiang Province, China. The results showed that the K+, Na+, Ca2+ and Mg2+ values in the bulk soil were higher than those in the rhizosphere soil, with significant differences in S2 and S3 (p < 0.05). The enzyme activities of alkaline phosphatase (ALP), invertase, urease and catalase (CAT) were lower in the bulk soil than those in the rhizosphere. Principal coordinate analysis (PCoA) demonstrated that the soil microbial community structure exhibited significant differences between different salinized soils (p < 0.001). Data implied that the fungi were more susceptible to salinity stress than the bacteria based on the Shannon and Chao1 indexes. Mantel tests identified Ca2+, available phosphorus (AP), saturated electrical conductivity (ECe) and available kalium (AK) as the dominant environmental factors correlated with bacterial community structures (p < 0.001); and AP, urease, Ca2+ and ECe as the dominant factors correlated with fungal community structures (p < 0.001). The relative abundances of Firmicutes and Bacteroidetes showed positive correlations with the salinity gradient. Our findings regarding the bacteria having positive correlations with the level of salinization might be a useful biological indicator of microorganisms in saline soils.

Section: Discussionmentioning

confidence: 99%

Responses of the Soil Microbial Community to Salinity Stress in Maize Fields

Zeng

et al. 2021

Biology

“…Additionally, a protein annotated as containing an OpuAC domain (VME_07510), that has a function assigned to choline transport and choline binding, was upregulated at high salinity in V. harveyi . While glycine betaine is a well-known osmoprotectant, choline is a metabolic precursor for glycine betaine biosynthesis, but it was also recognized to have a strong osmoprotective effect itself (e.g., in Pseudomonas syringae ) [ 26 ]. Intracellular accumulation of compatible solutes is obtained either by uptake from the environment or de novo biosynthesis, and transport of these solutes is much less energy-consuming in comparison to their biosynthesis [ 26 , 85 ].…”

Section: Resultsmentioning

confidence: 99%

“…While glycine betaine is a well-known osmoprotectant, choline is a metabolic precursor for glycine betaine biosynthesis, but it was also recognized to have a strong osmoprotective effect itself (e.g., in Pseudomonas syringae ) [ 26 ]. Intracellular accumulation of compatible solutes is obtained either by uptake from the environment or de novo biosynthesis, and transport of these solutes is much less energy-consuming in comparison to their biosynthesis [ 26 , 85 ]. Indeed, under our experimental conditions, we observed an increased abundance of compatible solute transporters in response to high salinity, indicating that osmolyte uptake takes precedence over biosynthesis, as a less energy-consuming response to changing osmolarity.…”

Section: Resultsmentioning

confidence: 99%

“…Despite such difficult conditions, the marine environment constitutes the largest habitat on Earth in terms of the area and the number of species. At a molecular level, the free-living bacteria’s response to changes in salt concentrations in their environment has been studied in bacterial species from various habitats, including Caulobacter crescentus (found in fresh water habitats) , Vibrio vulnificus (coastal waters) , V. parahaemolyticus (warm coastal waters), and Salinispora (marine sediments) [ 21 , 22 , 23 , 24 , 25 , 26 ]. Here, we chose three bacteria from distinct marine habitats: Shewanella baltica (found in both fresh and marine waters), V. harveyi (a facultative marine fish and invertebrate pathogen) and Aliivibrio fischeri (present in the temperate and subtropical global marine environments, also living as a squid symbiont), as models in our study.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Three Microbial Musketeers of the Seas: Shewanella baltica, Aliivibrio fischeri and Vibrio harveyi, and Their Adaptation to Different Salinity Probed by a Proteomic Approach

Kłoska

Cech

Nowicki

et al. 2022

IJMS

Osmotic changes are common challenges for marine microorganisms. Bacteria have developed numerous ways of dealing with this stress, including reprogramming of global cellular processes. However, specific molecular adaptation mechanisms to osmotic stress have mainly been investigated in terrestrial model bacteria. In this work, we aimed to elucidate the basis of adjustment to prolonged salinity challenges at the proteome level in marine bacteria. The objects of our studies were three representatives of bacteria inhabiting various marine environments, Shewanella baltica, Vibrio harveyi and Aliivibrio fischeri. The proteomic studies were performed with bacteria cultivated in increased and decreased salinity, followed by proteolytic digestion of samples which were then subjected to liquid chromatography with tandem mass spectrometry analysis. We show that bacteria adjust at all levels of their biological processes, from DNA topology through gene expression regulation and proteasome assembly, to transport and cellular metabolism. The finding that many similar adaptation strategies were observed for both low- and high-salinity conditions is particularly striking. The results show that adaptation to salinity challenge involves the accumulation of DNA-binding proteins and increased polyamine uptake. We hypothesize that their function is to coat and protect the nucleoid to counteract adverse changes in DNA topology due to ionic shifts.

“…The optimal concentration of 3% NaCl has been used in the different media for the growth and isolation of this Vibrio (Wong and Wang, 2004). To support the cell stability in the presence of high salinity concentrations, Vp has different halophilic proteins, characterized by a large number of acidic amino acids, negatively charged with hydrated carboxyl groups, and less in hydrophobic amino acids (Ongagna-Yhombi and Boyd, 2013; Gregory and Boyd, 2021). Lysine decarboxylase (encoded by cadA) is another acid-resistance transcriptional system that has been well-characterized in enteric pathogens (Neely and Olson, 1996;Merrell and Camilli, 1999).…”

Section: Adaptations To Salinity Oxidative and Ethanol Stressesmentioning

confidence: 99%

Adaptations of Vibrio parahaemolyticus to Stress During Environmental Survival, Host Colonization, and Infection

2021

Vibrio parahaemolyticus (Vp) is an aquatic Gram-negative bacterium that may infect humans and cause gastroenteritis and wound infections. The first pandemic of Vp associated infection was caused by the serovar O3:K6 and epidemics caused by the other serovars are increasingly reported. The two major virulence factors, thermostable direct hemolysin (TDH) and/or TDH-related hemolysin (TRH), are associated with hemolysis and cytotoxicity. Vp strains lacking tdh and/or trh are avirulent and able to colonize in the human gut and cause infection using other unknown factors. This pathogen is well adapted to survive in the environment and human host using several genetic mechanisms. The presence of prophages in Vp contributes to the emergence of pathogenic strains from the marine environment. Vp has two putative type-III and type-VI secretion systems (T3SS and T6SS, respectively) located on both the chromosomes. T3SS play a crucial role during the infection process by causing cytotoxicity and enterotoxicity. T6SS contribute to adhesion, virulence associated with interbacterial competition in the gut milieu. Due to differential expression, type III secretion system 2 (encoded on chromosome-2, T3SS2) and other genes are activated and transcribed by interaction with bile salts within the host. Chromosome-1 encoded T6SS1 has been predominantly identified in clinical isolates. Acquisition of genomic islands by horizontal gene transfer provides enhanced tolerance of Vp toward several antibiotics and heavy metals. Vp consists of evolutionarily conserved targets of GTPases and kinases. Expression of these genes is responsible for the survival of Vp in the host and biochemical changes during its survival. Advanced genomic analysis has revealed that various genes are encoded in Vp pathogenicity island that control and expression of virulence in the host. In the environment, the biofilm gene expression has been positively correlated to tolerance toward aerobic, anaerobic, and micro-aerobic conditions. The genetic similarity analysis of toxin/antitoxin systems of Escherichia coli with VP genome has shown a function that could induce a viable non-culturable state by preventing cell division. A better interpretation of the Vp virulence and other mechanisms that support its environmental fitness are important for diagnosis, treatment, prevention and spread of infections. This review identifies some of the common regulatory pathways of Vp in response to different stresses that influence its survival, gut colonization and virulence.