Transposition and expression of GEP gene in the genome of Vibrio harveyi to monitor its adherence in shrimp larvae

Expression of green fluorescent protein encoded by GFP gene in Vibrio harveyi was investigated to understand the ability of the gene as a molecular marker for adherence of this pathogenic Vibrio in shrimp larvae. The GFP gene was inserted into pUC18Not and pUTmini-Tn5 to generate a recombinant plasmid pWGO2 and pWGO3, respectively, which was transferred into the three isolates of V. harveyi employing diparental mating. Recombinant E. coli carrying pWGO2 and pWGO3 resulted in green-fluorescent colonies and cells due to the production of GFP. However, al1 of mini-Tn5, including mini-Tn5-gfp were not successful1y transferred to V. harveyi. Therefore, we used mini-Tn10 (pLOFKm-gfp) for inserting of gfp gene into V. harveyi genome. Although we could obtain relatively high (l0 pangkat -8) transconjugans employing Tn10, only one of Tnl0 derived isolate of V. harveyi G3 (G3-Tn1Ogfp) showed gfp expression and was further employed for adherence assay. Fluorescent 03-TnlOgfp cells could be observed inside the digestive tract of shrimp larvae and could be distinguished from vibrio that naturally exist in shrimp larvae.