(P27-014-24) Population Study of the Microbiota Before and After Curing of Vanilla planifolia

Objectives: To assess the impact of the curing process in microbial populations of Vanilla planifolia by changing the killing process, known to influence vanillin yield.

Methods: V. planifolia pods were treated under four killing conditions: hot water at 80°C (80W), microwave (MIC), sonication (SON), and freezing at -10°C (FREE), and control (C). gDNA was extracted with a column-based kit. Amplification of the 16S gene was performed, followed by gene sequencing using MiSeq Illumina. Raw data was filtered and trimmed. Taxonomic assignment and analysis of the sequences were performed using Kraken2. Bacterial composition analysis, α- and β-diversity were performed using the different packages in RStudio software. An analysis of variance and Tukey's test (p < 0.05) were performed to compare means using Minitab software.

Results: Curing resulted in a greater diversity on microbial populations compared to C. In C, Limnospira (28%), Enterococcus (11%), and Brevundimonas (13%) are the most relatively abundant genera. In contrast, after curing, Limnospira (22%) decreased and Brevundimonas (18%) increased in SON; Bacillus (26%), Staphylococcus (23%) are major in 80W and MIC, respectively, Enterococcus (23%) being major in MIC; Kosakonia (28%) and Komagataeibacter (15%) were exclusively found in FREE. In α-diversity, there was a higher diversity (p < 0.05) in C (349) and after curing (255-302). Except for SON, cured samples showed a higher diversity index than C. In contrast, C showed a greater dominance index compared to cured treatments. For β-diversity, MIC treatments clustered together and showed significant dissimilarity with respect to C along the first principal coordinate (variance explained=83%). This was tested by similarity analysis (ANOSIM), where the model revealed a significant difference (R²=0.485, p=0.003) in the bacterial community compositions of the killing process.

Conclusions: Killing treatments modified the composition of the microbiota of vanilla pods, which could have an influence in the pods phytochemical profile. These findings suggest that killing during curing could modulate the microbiota and provide important organoleptic characteristics.

Funding Sources: Author Cuan Escobar is supported by a scholarship from CONAHCYT. Financial support for tests was obtained from The Institute for Obesity Research.