Characterization of Bacillus sp. SFC 500-1E, a bioremediation agent used for treatment of tannery effluents

PEREIRA, PAOLA P.; FERNANDEZ M; GONZALEZ P; AGOSTINI E

San Luis

Congreso; XIII CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL (SAMIGE 2018), San Luis, 8-10 de Agosto de 2018.; 2018

Strain SFC 500-1E was originally isolated from sludge of a tannery industry located in Córdoba province.This isolate belongs to the genus Bacillus, which contains Gram-positive aerobic or facultative anaerobic rod-shaped bacteria that form intracelular spores. In a first step, based on biochemical and morpho-physiological tests performed according to Holt and Slepecky and Hemphill keys, this bacterium was identified as B. cereus. Supplementary physiological tests were evaluated using API 50CH profile analysis (Biomérieux). Based on this study, the significant taxon to which the SFC 500-1E isolate belongs was B. cereus (ID% = 93.5), with a note of possible identification as B. thuringiensis. In the last few years systematics of the genus was substantially revised, new species have been described and many others were renamed, even assigned to new genera. Also, the genus Bacillus contains several closely related species group, whose delimitation is difficult, especially within B. cereus group to which Bacillus sp. SFC 500-1E belongs. Analysis of 16S rDNA sequence, using for comparissons the NCBI ribosomal database, indicated a close relationship of the strain with B. thuringiensis; however, no parasporal crystal was observed with optical or electron microscopy techniques and no amplification product was obtained when parasporal crystal genes (cryIA, cryIG and cryIIIC) were analyzed. By using a ?cured? database (RDB) for 16S rDNA sequences, Bacillus sp. SFC 500-1E was 100% similar to B. toyonensis type strain (BCT-7112). Further multilocus sequence analysis (MLSA), including recA, rpoB and gyrB sequences of the isolate, also indicated maximum similarity with B. toyonensis strain BCT-7112. In addition, an specific multiplex PCR method that allows discrimination between different Bacillus species was carried out. The resultant amplification pattern of SFC 500-1E coincided with that presented by B. toyonensis type strain. Despite these similarities, certain peculiarities of the isolate emerged from the taxonomic analysis (with regard to specific profile of carbohydrate utilization, amplification of gyrB sequences with B.thuringiensis specific primers and fatty acids profile) lead us to consider that it can be described under another denomination. In this sense, the analysis by means of average nucleotide identity (ANI) calculations through the use of data from complete genome sequencing, will allow assigning Bacillus sp. 500-1E to a genomospecies with the greatest precision achievable.