Identification of N-acyl-l-homoserine lactones produced by non-pigmented Chromobacterium aquaticum CC-SEYA-1T and pigmented Chromobacterium subtsugae PRAA4-1T

Many members of the genus Chromobacterium produce violacein, a characteristic purple pigment which is induced by small diffusible N-acyl homoserine lactones (AHL) quorum-sensing molecules. In this study, the production of AHL of the non-pigmented C. aquaticum CC-SEYA-1T and the pigmented C. subtsugae PRAA4-1T were determined by using a CV026 biosensor assay. The profile of AHL was identified from the extracts of stationary phase cultures using gas chromatography–mass spectroscopy (GC–MS) and thin layer chromatography (TLC). CV026 biosensor assay revealed that both the non-pigmented C. aquaticum CC-SEYA-1T and the pigmented C. subtsugae PRAA4-1T produced AHL molecules, which were identified, respectively, as N-octanoyl homoserine lactone (OHL) [also known as C-8 homoserine lactone (C8-HSL)] and N-hexanoyl homoserine lactone (HHL) [also known as C-6 homoserine lactone (C6-HSL)]. The pigment produced by C. subtsugae PRAA4-1T was similar to that of Chromobacterium violaceum ATCC12472T but no characteristic visible spectral peaks of the pigment were observed in the extracts of C. aquaticum CC-SEYA-1T. In addition, C. aquaticum CC-SEYA-1T and C. subtsugae PRAA4-1T showed hemolytic activities

Diversity of Chromobacterium violaceum isolates from aquatic environments of state of Pará, Brazilian Amazon

The present study intended to characterize the phenotypic and genetic diversity of Brazilian isolates of Chromobacterium violaceum from aquatic environments within the Amazon region. Nineteen isolates showed morphological properties of C. violaceum and the majority grew at 44°C. Low temperatures, in contrast, showed to be inhibitory to their growth, as eleven isolates did not grow at 10ºC and nine did not produce pigmentation, clearly indicating an inhibition of their metabolism. The largest variation among isolates was observed in the citrate test (Simmons), in which 12 isolates were positive, and in the oxidation/fermentation of sucrose, with six positives isolates. Chloramphenicol, gentamicin and sulfonamides efficiently inhibited bacterial growth. Amplified products of the recA gene were digested with HindII or PstI, which produced three or four restriction fragments patterns, respectively. The combined analysis arranged the isolates into six genospecies. The higher diversity observed in Belém (genotypes C, D, E and F) may be a consequence of intense human occupation, pollution of the aquatic environment or due to the higher diversity of the environments sampled in that region. In conclusion, a high level of genetic and phenotypic diversity was observed, and four new genospecies were described