title: Microbiota and metabolome during controlled and spontaneous fermentation of Nocellara Etnea table olives.
abstract: This study is aimed to investigate bacterial community and its dynamics during the fermentation of Nocellara Etnea table olives and to study its effect on metabolome formation. Six different combination of bacterial cultures (BC1-BC6) were used as starters for table olive fermentation and one additional process, conducted without addition of any starters, was used as control (C). The processes were conducted in triplicate and, overall, 21 vessels were performed at industrial scale. The fermentation was monitored for 120 days through culture-dependent and -independent approaches. Microbial counts of the main microbial groups revealed slight differences among brine samples, with the exception of LAB counts and Enterobacteriaceae, which were higher and lower, respectively, in most of the inoculated samples than the control ones. In addition, results demonstrated that the use of bacterial cultures (except the BC1), singly or in different combinations, clearly influenced the fermentation process reducing the final pH value below 4.50. When microbiota was investigated through sequencing analysis, data revealed the presence of halophilic bacteria and, among lactobacilli, the dominance of Lactobacillus plantarum group at the initial stage of fermentation, in all brine samples, except in the BC5 in which dominated Lactobacillus casei group. At 60 and 120 days of fermentation, an overturned bacterial ecology and an increase of biodiversity was observed in all samples, with the occurrence of Lactobacillus paracollinoides, Lactobacillus acidipiscis and Pediococcus parvulus. Correlation between bacterial OTU and volatile organic compounds (VOCs) revealed that, aldehydes and alcohol compounds exhibited a positive correlation with Proteobacteria, while several esters with LAB and Hafnia. In particular, esters, associated with fruity and floral notes, were positively correlated to L. paracollinoides, L. acidipiscis, and P. parvulus species. Although the VOCs amounts were sample-specific, overall aldehydes were mostly produced at the beginning of the fermentation, while acids, alcohols and esters at the end of the process.
authors.affiliation: Department of Agricultural, Food and Environment, University of Catania, Italy. Electronic address: cranda@unict.it.
authors.forename: Cinzia Lucia
authors.initials: CL
authors.lastname: Randazzo
authors.affiliation: Department of Agricultural and Forest Science, University of Palermo, Italy.
authors.forename: Aldo
authors.initials: A
authors.lastname: Todaro
authors.affiliation: Department of Agricultural, Food and Environment, University of Catania, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pino
authors.affiliation: Department of Agricultural, Food and Environment, University of Catania, Italy.
authors.forename: Iole
authors.initials: I
authors.lastname: Pitino
authors.affiliation: Department of Agricultural and Forest Science, University of Palermo, Italy.
authors.forename: Onofrio
authors.initials: O
authors.lastname: Corona
authors.affiliation: Department of Agricultural, Food and Environment, University of Catania, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Caggia
mesh_terms: D044822:Biodiversity; D004755:Enterobacteriaceae / Q000235:genetics / Q000378:metabolism; D004952:Esters / Q000032:analysis; D005285:Fermentation; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D048191:Lactiplantibacillus plantarum / Q000235:genetics / Q000378:metabolism; D055442:Metabolome; D064307:Microbiota / Q000235:genetics / Q000502:physiology; D031658:Olea / Q000382:microbiology*; D019936:Probiotics / Q000378:metabolism; D012492:Salts / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013649:Taste; D055549:Volatile Organic Compounds / Q000032:analysis; D015003:Yeasts / Q000502:physiology
chemical_list: D004952:Esters; D012492:Salts; D055549:Volatile Organic Compounds; C017082:brine
keywords: LAB; Starter cultures; Table olives; VOCs