New Insights into Microbial Diversity of the Traditional Packed Table Olives Alorena de Malaga through Metataxonomic Analysis

Alorena de Malaga is a table olive especially characterised by its natural freshness and short shelf-life. In this work, we applied a metataxonomic approach to unravel the microbial diversity of bacterial and fungi populations through the shelf-life of traditionally packed Alorena de Malaga. A significant increase in lactic acid bacteria and mesophilic aerobic populations was observed during shelf-life, reaching the maximum population levels (4-5 log(10) CFU) at the end of the study (260 days). On the contrary, a rapid reduction in yeast and mould populations was reported. The use of a metataxonomic analysis based on the amplification of 16S (bacteria) and internal transcribed spacer (ITS) region (fungi) regions revealed a low diversity for both microbial groups. Lactiplantibacillus (65.05 +/- 8.65% in brine vs. 58.70 +/- 15.70% in fruit), Pediococcus (28.17 +/- 7.36% in brine vs. 27.20 +/- 15.95% in fruit), and Celerinatantimonas (4.64 +/- 1.08% in brine vs. 11.82 +/- 18.17% in fruit) were the main genera found among bacteria, and an increase in Lactiplantibacillus and a reduction in Celerinatantimonas populations during the shelf-life were observed. On the other hand, Citeromyces was the dominant fungi genus (54.11 +/- 2.00% in brine vs. 50.91 +/- 16.14% in fruit), followed by Candida (8.80 +/- 2.57% in brine vs. 12.32 +/- 8.61% in fruit) and Penicillium (6.48 +/- 1.87% vs. 8.48 +/- 4.43% in fruit). No food-borne pathogen genera were detected in any of the samples analysed, indicating the high level of food safety found in this ready-to-eat fermented vegetable. Data obtained in this work will help in the design of new strategies for the control of microbial populations during the shelf-life of Alorena de Malaga.

Automated summary

This study used a metataxonomic approach to uncover the microbial diversity of bacterial and fungi populations in traditionally packed Alorena de Malaga throughout its shelf-life, revealing a significant increase in lactic acid bacteria and mesophilic aerobic bacteria, and a rapid reduction in yeast and mould populations. Metataxonomic analysis based on 16S and ITS regions showed low diversity for both microbial groups, with certain genera like Lactiplantibacillus and Citeromyces dominating the bacterial and fungi populations respectively. No food-borne pathogens were detected, indicating a high level of food safety in this fermented vegetable product. Data obtained from this study can aid in designing new strategies for controlling microbial populations during the shelf-life of Alorena de Malaga.