The Study On The Effect Of The CNTs/PDMS Composites On The Pioneer Fouling Microbial Communities

With the constantly deepening of the development and the utilization of marine resources, the hazards triggered by marine biofouling have won widespread attention and concerns all over the world. The low-surface-energy anti-biofouling coatings have become a new research hot-spot in the marine coating industry. Polydimethylsiloxane(PDMS) has been considered to be one of the most attractive silicone elastomer for the protection of the ship hulls.In this study, a set of CNTs/PDMS composites were prepared by incorporating 0.1wt% carbon nanotube(CNT) fillers into the PDMS matrix. The CNTs/PDMS composites with excellent anti-biofouling capacity were screened and determined via the marine field studies, combining with the analysis of possible structure-function relationships between the surface structures and anti-biofouling properties of the CNTs/PDMS composites. The interactions between the CNTs/PDMS composites and the pioneer biofilm communities, along with the effect of the CNTs/PDMS composites on the community structures and dis tributions, diversity and richness, and the succession process of the dominant population of the pioneer prokaryotic and eukaryotic communities were investigated in detail. The preliminary discussions on the possible anti-biofouling mechanisms of the CNTs/PDMS composites against biofouling were explored from the aspect of ecology of microbial communities.Seven anti-biofouling potential of the CNTs/PDMS composites(i.e. the D12, D19, D33, D37, D38, D40 and D41 surfaces) were identified via the marine field assays from 118 kinds of CNTs/PDMS composites, among which the D19(PM) and D33(PC) surfaces with good repeatability, stability and exceptional anti-biofouling properties were determined in the field. The PM and PC surfaces can effectively prevent biofouling for about 14 weeks. The MDS analysis indicated that the wall-layers, lengths and the chemical modification of the CNT fillers may have significant effects on the anti-biofouling properties of the PDMS matrix, suggesting that not all CNT fillers have reinforcing effect on the anti-biofouling properties of the PDMS matrix. The SEM and AFM analysis revealed that the local aggregation of the CNT fillers in the PDMS matrix may have no effects on the anti-biofouling capacity for the PDMS matrix.The results obtained from the analysis of pioneer microbial communities grown on 18 kinds of CNTs/PDMS composite(PCs) indicated that these PCs surfaces have significant modulating effect on the pioneer eukaryotic microbial communities. Most PCs surfaces can significantly reduce the diversity and richness of the pioneer eukaryotic microbial communities, and effectively prevent the colonization and growths of the pioneer eukaryotic microbes. Six carboxyl-modified MWNTs/PDMS surfaces(i.e. the CPs surfaces, C1-C6) were able to prevent the colonization and growths of the pioneer prokaryotic and eukaryotic microbes at the same time, thereby being capable of preventing the microfouling triggered by the colonization of the pioneer microbes. The clustering result based on the MDS analysis suggested that the types of the PCs may have significant effect on the clustering features of the pioneer prokaryotic and eukaryotic communities. This result suggested that the clustering features of pioneer prokaryotic and eukaryotic com munities adhering to different PCs surfaces may not be directly related to their anti-biofouling capacity.The distribution features of the pioneer microbial communities grown on the P 0 surface, PM and PC surfaces(i.e. the D19 and D33 surfaces) were investigated using the the SSCP technique as well as the n MDS method.The results indicated that the pioneer prokaryotic and eukaryotic communities on the P0 surface was found to be relatively evenly-distributed and stable, and the dominant population were not obvious in the pioneer biofilm communities. The pioneer microbial communities on the P0 surface may have strong capabilities to resist to the environmental disturbance, which were less prone to undergone the large-scaled community succession progress. In addition, the pioneer prokaryotic and eukaryotic communities on the PM and PC surfaces were found to be unevenly-distributed and unstable, and the dominant population were obvious in the pioneer biofilm communities. The pioneer microbial communities on the PM and PC surfaces may have weak capabilities to resist to the environmental disturbance, which were more prone to undergone the large-scaled community succession progress.Therefore, these combined results suggested that the possible mechanisms of the PM and PC surfaces against pioneer biofouling may be primarily achieved via the modulating of the dynamics of the pioneer eukaryotic microbial-communitiy structures. The PM and PC surfaces can significantly reduce the diversity of the pioneer eukaryotic microbial communities, defer the development and maturity of the biofilm, and then effectively prevent the colonization and growths of pioneer eukaryotic microbes. In addition, the PM and PC surfaces can reduce the distribution uniformity and stability, accelerate the succession patterns and process, and then promote the renewal rate of the pioneer prokaryotic and eukaryotic microbes in the pioneer biofilm communities, thereby further weakening the oriented-attachment and colonization of the juvenile major fouling organisms.