Evaluation of process involved in the production of aromatic compounds in Gram-negative bacteria isolated from vanilla (Vanilla planifolia ex. Andrews) beans.

Abstract

The present investigation was aimed at isolating and identifying bacterial strains from cured vanilla beans. Additionally, the study focused on evaluating bacterial processes pertaining to the aromatic compounds production (ACP). Three bacteria were isolated from Vanilla planifolia beans, previously subjected to the curing process. According to morphological, biochemical and 16S rRNA analysis, the strains were identified as Citrobacter sp., Enterobacter sp. and Pseudomonas sp. The polygalacturonase activity (PGA) was determined using the drop, cup-plate and DNS methods. Aromatic compounds production was analysed by cup-plate method using FA as substrate and quantified by high performance liquid chromatography (ppm), the functional groups of vanillic acid (VA) were identified by FT-IR and the aromatic compounds (AC) resistance was determined and reported as minimum inhibitory concentration. Citrobacter sp., Enterobacter sp. and Pseudomonas showed PGA (70·31±364, 76·07±12·47 and 51±10·92Uml-1 respectively), were producers of VA (3·23±0·49, 324±41 and 265·99±11·61ppm respectively) and were resistant to AC. The Gram-negative bacteria isolated from V. planifolia beans were responsible for ACP. This is the first evidence for the role of Gram-negative bacterial isolates from cured Mexican V. planifolia beans in the process related to ACP.