Toolkit development for cyanogenic and gold biorecovery chassis Chromobacterium violaceum .

has been of interest recently due to its cyanogenic ability and its potential role in environmental sustainability the biorecovery of gold from electronic waste. However, as with many non-model bacteria, there are limited genetic tools to implement the use of this gram-negative chassis in synthetic biology. We propose a system that involves assaying spontaneous antibiotic resistances and using broad host range vectors to develop episomal vectors for non-model gram-negative bacteria. These developed vectors can subsequently be used to characterize inducible promoters for gene expressions and implementing CRISPRi to inhibit endogenous gene expression for further studies. Here, we developed the first episomal genetic toolkit for consisting of two origins of replication, three antibiotic resistance genes and four inducible promoter systems. We examined the occurrences of spontaneous resistances of the bacterium to the chosen selection markers to prevent incidences of false positives. We also tested broad host range vectors from four different incompatibility groups and characterized four inducible promoter systems, which potentially can be applied in other gram-negative non-model bacteria. CRISPRi was also implemented to inhibit violacein pigment production in . This systematic toolkit will aid future genetic circuitry building in this chassis and other non-model bacteria for synthetic biology and biotechnological applications.