Functionalized Graphene Oxide In Microbial Engineering: An Effective Stimulator For Bacterial Growth

Grephene-based materails have attracted much attention recently because of unique physicochemical properties towards biomedical applications. Whether graphene and graphene oxide (GO) would affect the activities of bacteria, acting as either an antimicrobial agent or a stimulator to enhance bacterial growth, has been under debate. Particularly, how graphene derivatives with biocompatible coatings interact with microorganisms and the underlying mechanisms remain to be further explored. To this end, three types of PEGylated nano-GOs (nGO-PEGs) with various PEGylation degrees were synthesized, and their effects on Escherichia coli (E. coli) growth were carefully investigated. Interestingly, nGO-PEG(1:1) with a relatively low PEGylation level (GO:PEG feeding ratio=1:1, w/w) could induce a significant increase in bacterial growth by shortening the bacterial growth cycle, while GO and the other two nGO-PEGs did not showed similar effect. Further analysis revealed that E. coli cells treated with nGO-PEG(1:1) showed dramatically increased DNA synthesis and promoted secretion of extracellular polymeric substance (EPS). Production of recombinant proteins in engineered bacteria cells were also remarkably enhanced upon nGO-PEG(1:1) treatment, indicating promising applications of nGO-PEG(1:1) in microbial engineering.The development of DNA recombination techniques since late 1970s has enabled production of proteins of interests in host cells at all scales. Since then, recombinant protein production has become more and more critical for both biomedical research and industry, especially for the pharmaceutical industry. The results above have successfully demonstrated that nGO-PEG(1:1) could greatly stimulate the growth of bacteria. To the best of our knowledge, this work is the first demonstration of functionalized GO as a positive regulator in microbial engineering. Moreover, our work highlights the critical role of surface chemistry and nano-bio interface in modulating the interactions between nanomaterials and microorganisms.