旭硝子財団助成研究成果報告2020

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87Sarawut Cheunkar 88Lakha SalaipethSystematic Investigation of Biofilm Formation of Acetogens and Methanogens Derived from Argo-Industrial Wastewater Using Microfluidic Devices and Applied Bio-interface Chemistry (Project 2018)Field Isolated Mycoviruses to Control Mango’s Anthracnose Disease Caused by Collectotrichum gloeosporioides (Project 2018)62旭硝子財団　助成研究成果報告（2020）In anaerobic wastewater treatment, biofilm is beneficial for substrate utilization and for preventing the wash-out of key microorganisms. Biofilm formation can be accelerated by introducing solid supports due to the early initial adhesion of residing microbes. Alteration in surface properties is therefore one such approach that helps us understand microbial interfacial interaction. Here, self-assembled monolayers of alkanethiols with carboxyl (-COOH), hydroxyl (-OH), and amine (-NH2) terminal moieties on gold (Au) substrates were employed to study the initial adhesion of wastewater microbes. An elastomeric flow cell was also utilized to simulate the environment of wastewater bioreactors. Results from fluorescence in situ hybridization (FISH) portrayed more enhanced microbial adhesion after 2 h on -NH2 functional group with the calculated surface coverage of 12.8 ± 2.4% as compared to 7.7 ± 1.6% on -COOH, 11.0 ± 2.0% on -OH, and 1.2% on unmodified Au surfaces. This might be because of concomitant electrostatic attraction between negatively-+) functional groups. Nevertheless, the average surface charged bacteria and positively-charged (-NH3coverage by individual biofilm clusters was 28.0 ± 5.0 µm2 and 32.0 ± 9.0 µm2 on -NH2 and -OH surfaces, respectively, while -COOH surfaces resulted in higher value (60.0 ± 5.0 µm2) and no significant cluster formation was observed on Au surfaces. Accordingly, the average inter-cluster distance observed on -NH2 surfaces was relatively smaller (3.0 ± 0.6 µm) as compared to that on other surfaces. Overall, these data suggest favorable initial biofilm growth on more hydrophilic and positively-charged surfaces. Furthermore, the analysis of the mean fluorescence intensity revealed preferred initial adhesion of key microbes (archaea) on -OH and -NH2 surfaces. Indeed, results obtained from this study would be beneficial in designing selective biointerfaces for certain biofilm carriers in a typical wastewater bioreactor. Importantly, our elastomeric flow cell integrated with SAM-modified surfaces demonstrated an ideal platform for high-throughput investigation of wastewater biofilm under controlled environments.Collectotrichum gloeosporioides, is an important plant pathogenic fungus causing anthracnose disease in plants worldwide and is responsible for significant economic losses. Although fungicides are available for controlling C. gloeosporioides, it is quite expensive and not always resolutive. Recently, mycoviruses or fungal viruses that alter hypovirulence factors, some of which reduce the aggressiveness of their host fungus, have been the subject of research interest because of their potential as biocontrol agents against plant pathogenic fungi. Trisegmented dsRNA containing field strain, Ssa-44, was isolated from C. gloeosporioides. The three dsRNA genomes size is ranging between 1.5-3.5 kbp. Virulence assay confirmed the ability to confer hypovirulence of C. gloeosporioides. A side from that, Ssa-44 hypovirulent strains can convert virulent strains to hypovirulence after anastomosis. Taking the data together, the results strongly suggest the ability of Ssa-44 to act as virocontrol agents.