The Alterations of Biofilm Formation and EPS Characteristics of a Diatom by a Sponge-Associated Bacterium Psychrobacter sp.

Abstract

A sponge-associated bacterium, which was identified as Psychrobacter sp. in this study, was found with high activity against biofilm formation of benthic diatoms, including Amphora sp., Nitzschia closterium, Nitzschia frustulum, and Stauroneis sp. The activity against diatom biofilm formation by the tested strain was confirmed mostly in the culture supernatant and could be extracted using organic solvents. Treatment with its supernatant crude extract significantly reduced the cells of Stauroneis sp. forming biofilm and slightly increased the cells floating in the culture medium, which results in the ratio of biofilm cell/floating cell altering from 0.736 in control to 0.414 in treatment. Use of the supernatant crude extract led to increased production of extracellular polymeric substances (EPSs) by diatom Stauroneis sp. from 16.66 to 41.59 (g/g cell dry weight). The increase in EPS production was mainly contributed by soluble EPS (SL-EPS) and followed by the EPS that was tightly bound to biofilm cells (BF-TB-EPS). In addition, the supernatant crude extract caused significant changes in the monosaccharides composition of the EPS of Stauroneis sp. Specifically, glucuronic acid (Glc-A) and N-acetyl-D-glucosamine (Glc-NAc) in BF-TB-EPS were 55% fold decreased and 1219% fold increased, respectively. Based on our findings, we proposed that these changes in monosaccharides composition might lead to a decreased biofilm formation efficiency of diatom.

Antimicrobial photodynamic therapy (aPDT) for biofilm treatments. Possible synergy between aPDT and pulsed electric fields

“…As mentioned above the secretion of EPS is an important virulence factor that confers to the microorganisms both increased antimicrobial resistance and defense from host immune responses [ 53 ]. The EPS acts as an adsorbent or reactant reducing the antimicrobials penetration by diffusion limitation and through chemical interactions with the ECM proteins and polysaccharides [ 54 ]. In addition, the aggregation of microorganisms into EPS-coated biofilms turns them less susceptible to phagocytosis [ 35 ].…”

First Record of Epizoic Diatom Presence on Poricellaria ratoniensis (Bryozoa, Cheilostomata) from Java Sea, Indonesia

“…Various species of diatoms are commonly found in marine invertebrates, including bryozoans [2]. Bryozoan provides a favorable microenvironment for a diverse range of epizoic diatoms [3]- [6]. The presence of diatoms on bryozoan and other marine invertebrates can have significant impacts including hosts' feeding, growth, and reproduction [5].…”