China News Service, Shanghai, August 29 (Reporter Xu Jing) The reporter learned from Shanghai Ocean University on the 29th that the school, together with the University of Algarve in Portugal, Shanghai Maritime University and other teams, recently published important research results online in the international journal "Corrosion Science", revealing for the first time the dual molecular mechanism of polar marine bacteria driving corrosion and biofouling at the same time through the secretion of the trimeric autotransport adhesin YadA protein.
Polar waters are a key frontier for global resource development and strategic competition, posing severe service challenges to marine engineering materials. The coupling effect of biofouling and corrosion caused by bacterial biofilm is the key biological inducement to accelerate material deterioration. However, there is still a lack of clear understanding of the molecular mechanisms of how polar marine bacteria mediate this degradation process.
The research team focused on Psychrobacterium, which is widely distributed in polar oceans, and found that its mechanism of action is different from that of common marine bacteria in temperate zones. It aggravates the corrosion deterioration of low-temperature steel and has a stronger induction rate of attachment and metamorphosis to large fouling organisms.
The research team found that there was no significant difference between the extracellular polysaccharides and extracellular lipids secreted by polar psychrotrophic bacteria and those of temperate bacteria; however, the extracellular protein content was much higher than that of temperate bacteria. In order to further explore whether polar psychrotrophic bacteria possess certain specific functional proteins that are different from those of normal-temperature bacteria that cause this phenomenon, the team used whole-genome sequencing and comparative genomics to discover that the trimeric autotransporting adhesin YadA protein gene only exists in polar marine bacteria and does not exist in temperate control bacteria.
The team then used gene knockout technology to targetedly knock out the "membrane anchoring region" gene 1308 responsible for anchoring YadA to the bacterial surface. The study found that the deletion of this gene significantly reduced the corrosion rate of polar marine bacteria and the attachment efficiency of mussel larvae. The original "villi-like" structure on the bacterial surface disappeared and the bacterial adhesion dropped by more than 80%, thus reducing the colonization of bacteria on the surface of low-temperature steel materials.
This study provides new research ideas for the prevention and control of biocorrosion and biofouling in polar marine environments. It also lays a theoretical foundation for the development of protective materials that accurately target adhesins and their secretion pathways.
