Genomic and phenotypic analyses of Serratia fonticola strain GS2: a rhizobacterium isolated from sesame rhizosphere that promotes plant growth and produces N-acyl homoserine lactone

The genus Serratia incorporates many agriculturally important species. Serratia fonticola strain GS2, isolated from a sesame rhizosphere, can produce N-acyl homoserine lactone quorum sensing signal molecules and indole-3-acetic acid (IAA). Here we report the complete genome sequence and phenotypic characteristics based on genomic information of this bacterium. The complete genome sequence of S. fonticola strain GS2 consists of a chromosome of 6.1 Mbp and two plasmids of 132 kbp and 94 kbp. The genome clusters for IAA and N-acyl homoserine lactone biosynthesis were identified in the genome. Subsequently, the Salkowski test and gas chromatography-mass spectrometry (GC–MS) analysis also revealed that the strain GS2 produces indolic compounds (27.1 μg mL⁻¹) and IAA (6.7 μg mL⁻¹) in its culture broth. HPLC analysis confirmed that the strain GS2 produced the quorum sensing signal molecules N-hexanoyl-_L-homoserine lactone and N-octanoyl-_L-homoserine lactone. This new information on the genome sequence and phenotype features will inform future ecological studies related to plant-microbe interactions.