Abstract:The growth of Vibrio bacteria is affected by environmental conditions, and unfavorable conditions will produce different degrees of stress on Vibrio. The cells respond to the stress on the bacteria through changes in biological characteristics and transcriptomes. To study the effect of NaCl concentration on Vibrio brasiliensis, we have determined the biological characteristics of the 0%, 1%, 2%, 3%, 5%, and 7% NaCl concentrations cultured V. brasiliensis to research the salt stress to bacteria. We found that t… Show more
“…The results of growth characterization also show that V. parahaemolyticus can grow well at 3 and 5% NaCl concentration, while at 0 and 1% NaCl concentration, there is a decrease in the growth index. Previous research reported the ability to grow Vibrio gradually decreased with increasing NaCl concentration (>6%) and decreased growth at NaCl concentration (<1.0%) (Hu et al, 2022). Another study reported that V. parahaemolyticus reached the maximum growth rate in the optimum environment with conditions of 37°C and 3% salinity (Liu et al, 2016).…”
Vibrio parahaemolyticus is a bacterium found in estuaries and marine and is a pathogenic bacterium that harms human health. Vibrio parahaemolyticus can contaminate fishery products and potentially contaminate lobster products in North Sulawesi. This study was conducted to determine the presence of V. parahaemolyticus in lobsters collected in two shelters in North Sulawesi. This study also serves as a monitoring function and a means of information on the presence of V. parahaemolyticus. The samples used were lobsters (Panulirus sp.) taken from Malalayang and Tuminting shelters in North Sulawesi. Observations in this study include total bacteria, total Vibrio, and identified V. parahaemolyticus. Isolates of V. parahaemolyticus were characterized by their growth at different temperatures (5, 37, 43 oC); pH (5 - 9); and concentrations of NaCl (0, 1, 3, 5%). The results show total plates for lobster meat from Malalayang 4.3×104 ‒ 1.0×105 CFU/g, while from Tuminting shelter 1.4×104 ‒ 3.9×104 CFU/g. The total plate on lobster gills from Malalayang is 6.2×104 ‒ 1.2×105 CFU/g, while from Tuminting shelter 2.0×104 ‒ 6.7×104 CFU/g. Total Vibrio in lobster meat from Malalayang 6.2×103 ‒ 1.4×104 CFU/g, while from Tuminting shelter 5.2×103 ‒ 7.9×103 CFU/g. Total Vibrio in lobster gills from Malalayang 8.5×103 ‒ 4.6×104 CFU/g, while from Tuminting shelter 7.8×103 ‒ 9.5×103 CFU/g. The Gram staining analysis obtained 96 isolate strains with Gram-negative rods, and 42 strains showed characteristics as V. parahaemolyticus based on the biochemical assay. Vibrio parahaemolyticus can grow optimally at 37°C, pH 7‒8, and NaCl concentration 3‒5%.
“…The results of growth characterization also show that V. parahaemolyticus can grow well at 3 and 5% NaCl concentration, while at 0 and 1% NaCl concentration, there is a decrease in the growth index. Previous research reported the ability to grow Vibrio gradually decreased with increasing NaCl concentration (>6%) and decreased growth at NaCl concentration (<1.0%) (Hu et al, 2022). Another study reported that V. parahaemolyticus reached the maximum growth rate in the optimum environment with conditions of 37°C and 3% salinity (Liu et al, 2016).…”
Vibrio parahaemolyticus is a bacterium found in estuaries and marine and is a pathogenic bacterium that harms human health. Vibrio parahaemolyticus can contaminate fishery products and potentially contaminate lobster products in North Sulawesi. This study was conducted to determine the presence of V. parahaemolyticus in lobsters collected in two shelters in North Sulawesi. This study also serves as a monitoring function and a means of information on the presence of V. parahaemolyticus. The samples used were lobsters (Panulirus sp.) taken from Malalayang and Tuminting shelters in North Sulawesi. Observations in this study include total bacteria, total Vibrio, and identified V. parahaemolyticus. Isolates of V. parahaemolyticus were characterized by their growth at different temperatures (5, 37, 43 oC); pH (5 - 9); and concentrations of NaCl (0, 1, 3, 5%). The results show total plates for lobster meat from Malalayang 4.3×104 ‒ 1.0×105 CFU/g, while from Tuminting shelter 1.4×104 ‒ 3.9×104 CFU/g. The total plate on lobster gills from Malalayang is 6.2×104 ‒ 1.2×105 CFU/g, while from Tuminting shelter 2.0×104 ‒ 6.7×104 CFU/g. Total Vibrio in lobster meat from Malalayang 6.2×103 ‒ 1.4×104 CFU/g, while from Tuminting shelter 5.2×103 ‒ 7.9×103 CFU/g. Total Vibrio in lobster gills from Malalayang 8.5×103 ‒ 4.6×104 CFU/g, while from Tuminting shelter 7.8×103 ‒ 9.5×103 CFU/g. The Gram staining analysis obtained 96 isolate strains with Gram-negative rods, and 42 strains showed characteristics as V. parahaemolyticus based on the biochemical assay. Vibrio parahaemolyticus can grow optimally at 37°C, pH 7‒8, and NaCl concentration 3‒5%.
“…Although Vibrio strains are halophilic, they exhibit varying growth patterns in response to different salt concentration conditions. When the salt concentrations are quite high, intracellular enzyme activity is reduced, material transportation is hindered, and growth inhibition also emerges [ 46 ]. Fig.…”
“…Though pathogenic Vibrionaceae species experience continuous shifts of NaCl concentration in their life cycles, very few species of this family have been the subject of global transcriptomic studies aimed at investigating the role of salinity in gene expression modulation. These include Vibrio cholerae ( 6 , 7 ), Vibrio parahaemolyticus ( 8 - 10 ), Vibrio brasiliensis ( 11 ), and Vibrio fujianensis ( 12 ). However, some of these studies focused on the study of salt stress and employed NaCl conditions that do not mimic those encountered in nature ( 12 ).…”
Facultative marine bacterial pathogens sense environmental signals so that the expression of virulence factors is upregulated on entry into hosts and downregulated during the free-living lifestyle in the environment. In this study, we utilized transcriptome sequencing to compare the transcriptional profiles of
Photobacterium damselae
subsp.
damselae
, a generalist pathogen that causes disease in diverse marine animals and fatal infections in humans at NaCl concentrations that mimic the free-living lifestyle or host internal milieu, respectively. We here show that NaCl concentration constitutes a major regulatory signal that shapes the transcriptome and uncover 1,808 differentially expressed genes (888 upregulated and 920 downregulated in response to low-salt conditions). Growth at 3% NaCl, a salinity that mimics the free-living lifestyle, upregulated genes involved in energy production, nitrogen metabolism, transport of compatible solutes, utilization of trehalose and fructose, and carbohydrate and amino acid metabolism with strong upregulation of the arginine deiminase system (ADS). In addition, we observed a marked increase in resistance to antibiotics at 3% NaCl. On the contrary, the low salinity conditions (1% NaCl) that mimic those encountered in the host triggered a virulence gene expression profile that maximized the production of the type 2 secretion system (T2SS)-dependent cytotoxins damselysin, phobalysin P, and a putative PirAB-like toxin, observations that were corroborated by the analysis of the secretome. Low salinity also upregulated the expression of iron-acquisition systems, efflux pumps, and other functions related to stress response and virulence. The results of this study greatly expand our knowledge of the salinity-responsive adaptations of a generalist and versatile marine pathogen.
IMPORTANCE
Pathogenic
Vibrionaceae
species experience continuous shifts of NaCl concentration in their life cycles. However, the impact of salinity changes in gene regulation has been studied in a small number of
Vibrio
species. In this study, we analyzed the transcriptional response of
Photobacterium damselae
subsp.
damselae
(
Pdd
), a generalist and facultative pathogen, to changes in salinity, and demonstrate that growth at 1% NaCl in comparison to 3% NaCl triggers a virulence program of gene expression, with a major impact in the T2SS-dependent secretome. The decrease in NaCl concentration encountered by bacteria on entry into a host is proposed to constitute a regulatory signal that upregulates a genetic program involved in host invasion and tissue damage, nutrient scavenging (notably iron), and stress responses. This study will surely inspire new research on
Pdd
pathobiology, as well as on other important pathogens of the family
Vibrionaceae
and related taxa whose salinity regulons still await investigation.
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