NaOH-debittering induces changes in bacterial ecology during table olives fermentation.
Limited information is available on the impact of the NaOH treatment on table olive fermentations, and for this reason a polyphasic approach has been adopted here to investigate its effect on the fermentation dynamics and bacterial biodiversity. The microbial counts of the main groups involved in the transformation have not shown any differences, apart from a more prompt start of the fermentation when the olives were subjected to the NaOH treatment. The data produced by culture-independent analyses highlighted that the fermentation of table olives not treated with NaOH is the result of the coexistence of two different ecosystems: the surface of the olives and the brines. A sodium hydroxide treatment not only eliminates this difference, but also affects the bacterial ecology of the olives to a great extent. As proved by high-throughput sequencing, the fermentation of the olives not treated with NaOH was characterized by the presence of halophilic bacteria, which were substituted by Lactobacillus at the later stages of the fermentation, while enterobacteria were dominant when the olives were treated with sodium hydroxide. Higher biodiversity was found for Lactobacillus plantarum isolated during untreated fermentation. Different biotypes were found on the olive surface and in the brines. When the debittering process was carried out, a decrease in the number of L. plantarum biotypes were observed and those originating from the surface of the olive did not differentiate from the ones present in the brines.
Dipartimento di Scienze Agrarie, Forestali e Alimentari, Università degli Studi di Torino, Grugliasco, Italy. lucasimone.cocolin@unito.it
Luca
L
Cocolin
Valentina
V
Alessandria
Cristian
C
Botta
Roberta
R
Gorra
Francesca
F
De Filippis
Danilo
D
Ercolini
Kalliopi
K
Rantsiou
D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D044822:Biodiversity; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000145:classification / Q000235:genetics; D017753:Ecosystem; D005285:Fermentation / Q000187:drug effects; D005516:Food Microbiology; D014644:Genetic Variation; D006863:Hydrogen-Ion Concentration; D031658:Olea / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D011157:Population Dynamics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012492:Salts; D017422:Sequence Analysis, DNA; D012972:Sodium Hydroxide / Q000494:pharmacology*; D013045:Species Specificity
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012492:Salts; C017082:brine; D012972:Sodium Hydroxide