Biosynthesis and uptake of glycine betaine as cold-stress response to low temperature in fish pathogen Vibrio anguillarum

Abstract

Fish pathogen Vibrio anguillarum, a mesophile bacterium, is usually found in estuarine and marine coastal ecosystems worldwide that pose a constant stress to local organism by its fluctuation in salinity as well as notable temperature change. Though V. anguillarum is able to proliferate while maintain its pathogenicity under low temperature (5-18°C), so far, coldadaption molecular mechanism of the bacteria is unknown. In this study, V. anguillarum was found possessing a putative glycine betaine synthesis system, which is encoded by betABI and synthesizes glycine betaine from its precursor choline. Furthermore, significant up-regulation of the bet gene at the transcriptional level was noted in log phase in response to cold-stress. Moreover, the accumulation of betaine glycine was only found appearing at low growth temperatures, suggesting that response regulation of both synthesis system and transporter system are cold-dependent. Furthermore, in-frame deletion mutation in the two putative ABC transporters and three putative BCCT family transporters associated with glycine betaine uptake could not block cellular accumulation of betaine glycine in V. anguillarum under coldstress, suggesting the redundant feature in V. anguillarum betaine transporter system. These findings confirmed that glycine betaine serves as an effective cold stress protectant and highlighted an underappreciated facet of the acclimatization of V. anguillarum to cold environments.

Transcriptome changes in response to temperature in the fish pathogen Photobacterium damselae subsp. damselae: Clues to understand the emergence of disease outbreaks at increased seawater temperatures

“…Biosynthesis and uptake of betaine glycine constitutes an adaptation for growth at low temperatures and is part of the cold-stress response of the marine fish pathogen Vibrio anguillarum [83]. Of note, a glycine betaine transporter showed a strong downregulation at 25°C in our study (Table 2).…”

Molecular and Physiological Adaptations to Low Temperature in Thioalkalivibrio Strains Isolated from Soda Lakes with Different Temperature Regimes

“…A key adaptation to reduced temperature is the production of compatible solutes and antifreeze proteins. Among these compatible solutes, glycine betaine is, apart from its feature as an osmolyte (46), also known to enhance cryotolerance in bacteria (21,(47)(48)(49). Accordingly, the glycine betaine concentration in both strains was higher at 10°C than at 30°C (Fig.…”

The Expression of Virulence Factors in Vibrio anguillarum Is Dually Regulated by Iron Levels and Temperature

“…The water temperature is a risk factor that enhances the occurrence of disease outbreaks caused by Vibrio species (Le Roux et al, 2015). V. anguillarum is able to cause disease outbreaks in a wide temperature range, since it can infect many different farmed fish species at both cold- and warm-water temperatures (Bellos et al, 2015; Ma et al, 2017; Rønneseth et al, 2017; Toranzo et al, 2017). On the other hand, pathogenic bacteria face a drastic shift in iron availability upon host encounter (Skaar, 2010).…”

“…Seasonal rising of seawater temperature has been associated with the proliferation of Vibrio species (Maeda et al, 2003), and hence, the occurrence of some fish diseases caused by these bacteria is also increased (Le Roux et al, 2015). V. anguillarum can cause vibriosis at low temperatures (5–18°C) (Ma et al, 2017), with 15°C considered as the optimal temperature to cause vibriosis outbreaks (Austin and Austin, 2007; Bellos et al, 2015). Thus, vibriosis episodes, as most ectothermic aquatic animal infectious diseases (Guijarro et al, 2015), usually occur at a temperature lower than that for the optimal growth of the bacteria.…”