Genomic and Transcriptomic Analysis Reveal Multiple Strategies for the Cadmium Tolerance in Vibrio parahaemolyticus N10-18 Isolated from Aquatic Animal Ostrea gigas Thunberg

Abstract

The waterborne Vibrio parahaemolyticus can cause acute gastroenteritis, wound infection, and septicemia in humans. Pollution of heavy metals in aquatic environments is proposed to link high incidence of the multidrug-resistant (MDR) pathogen. Nevertheless, the genome evolution and heavy metal tolerance mechanism of V. parahaemolyticus in aquatic animals remain to be largely unveiled. Here, we overcome the limitation by characterizing an MDR V. parahaemolyticus N10-18 isolate with high cadmium (Cd) tolerance using genomic and transcriptomic techniques. The draft genome sequence (4,910,080 bp) of V. parahaemolyticus N10-18 recovered from Ostrea gigas Thunberg was determined, and 722 of 4653 predicted genes had unknown function. Comparative genomic analysis revealed mobile genetic elements (n = 11) and heavy metal and antibiotic-resistance genes (n = 38 and 7). The bacterium significantly changed cell membrane structure to resist the Cd2+ (50 μg/mL) stress (p < 0.05). Comparative transcriptomic analysis revealed seven significantly altered metabolic pathways elicited by the stress. The zinc/Cd/mercury/lead transportation and efflux and the zinc ATP-binding cassette (ABC) transportation were greatly enhanced; metal and iron ABC transportation and thiamine metabolism were also up-regulated; conversely, propanoate metabolism and ribose and maltose ABC transportation were inhibited (p < 0.05). The results of this study demonstrate multiple strategies for the Cd tolerance in V. parahaemolyticus.

Comparative secretomic and proteomic analysis reveal multiple defensive strategies developed by Vibrio cholerae against the heavy metal (Cd2+, Ni2+, Pb2+, and Zn2+) stresses

“…In this study, our results revealed that the cytoplasma membrane permeability of V. cholerae J9-62 and Q6-10 isolates was significantly increased under the Pb 2+ (200 μg/mL), and Cd 2+ (12.5 μg/ mL) or Zn 2+ (50 μg/mL) stresses, respectively (p < 0.05). The increased inner membrane permeability was also found in V. parahaemolyticus N10-8 after treated with a sublethal concentration of Cd 2+ (50 μg/mL) in our recent study (Yu P. et al, 2022). Likewise, cell membrane fluidity affected most compounds and ions (such as nutrients and heavy metals) to cross the bacterial cytoplasma membrane (Bessa et al, 2018).…”

“…Changes in cell biophysical properties have been disclosed as stressors affecting compound and ion transport and cell integrity (Yu P. et al, 2022). Bacterial strains applied different mechanisms to response to heavy metals, such as bond formation between bacterial cell surface and metal ions to decrease their toxicity (Heidari and Panico, 2020;Wróbel et al, 2023).…”

“…Growth curves were measured using Bioscreen Automatic Growth Curve Analyzer (BioTek Instruments, Inc., Winooski, VT, USA) (Yang et al, 2020). Bacterial survival was examined using the standard plate counting method (Yu P. et al, 2022). The sublethal concentrations of the heavy metals were defined as fatality rates less than 50% under the treatment conditions for 2 h (Yu P. et al, 2022).…”

“…Bacterial survival was examined using the standard plate counting method (Yu P. et al, 2022). The sublethal concentrations of the heavy metals were defined as fatality rates less than 50% under the treatment conditions for 2 h (Yu P. et al, 2022).…”

“…The V. cholerae isolates were incubated in the TSB medium to the mid logarithmic growth phase (mid-LGP) at 37°C. A final concentration of Cd 2+ (12.5 μg/mL), Ni 2+ (50 μg/mL), Pb 2+ (200 μg/ mL), or Zn 2+ (50 μg/mL) was added to the bacterial culture (5 mL), and then continuously incubated at 37°C for 2 h, 4 h, and 6 h. The cell mixture (1.5 mL) was then harvested, washed, fixed, and observed using thermal field emission SEM (Hitachi, SU5000, Tokyo, Japan, 5.0 kV, ×30,000) as described in our recent report (Yu P. et al, 2022). The untreated bacterial culture was used as a negative control.…”