# Microbiota and Metabolite Profiling of Spoiled Spanish-Style Green Table Olives
## 4 Conclusions  
The microbiota and metabolites in spoiled Spanish-style table olives were disclosed, along with their relationships in the sensory evaluation and the correlations among them. A low salt concentration resulted in the main factor for prompting spoilage, whereas different alkaline and washing steps, which are crucial for this type of elaboration, were not significant in preventing or favoring deterioration. Some unexpected bacterial taxa, such as _Cardiobacteriaceae_ and _Ruminococcus_ turned out to be the most abundant microorganisms once the spoilage took place, and coexisted with _Pichia membranifaciens_, a common yeast species in table olives. The disappearance of lactic acid in the spoiled samples was the foremost metabolite difference between the spoiled and control samples. In addition, all the spoiled samples had higher contents of volatile acids and phenols than the control samples. Several volatile acids could contribute to the olive's off-odor as their concentrations were above the reported thresholds in water. Although the number of samples used in the present study was small, the associations found among microbial communities, metabolites, and sensory spoilage descriptors appeared quite reasonable in light of previous studies. Thus, it is not surprising that butyric and cyclohexanoic acids were among the main contributors to the butyric and zapatera off-odors, respectively. The butyric attribute exhibited a significant positive relationship with the genus _Ruminococcus_; whereas the genus _Propionibacterium_ was positively correlated with the zapatera descriptor. In addition, the statistical analyses revealed that the _Propionibacterium_ was positively correlated with acetic acid, propionic acid, succinic acid, and methyl propanoate. The propionic and butyric acids appeared to be correlated with _Ruminococcus_, although the correlations were at the margin of significance. On the other hand, _Cardiobacteriaceae_ was positively correlated with butyric acid, valeric acid, caprotic acid, 1-octanol, methyl pentanoate, methyl hexanoate, \(p\)-creosol, and \(p\)-cresol. Some of these compounds could be metabolic end-products generated as a result of the lactic acid metabolism by these bacteria. However, further studies concerning bacterial metabolism are required to confirm this hypothesis. The following are available online at [[http://www.mdpi.com/2218-1989/8/4/73/s1](http://www.mdpi.com/2218-1989/8/4/73/s1)]([http://www.mdpi.com/2218-1989/8/4/73/s1](http://www.mdpi.com/2218-1989/8/4/73/s1)). Table S1: Number of reads and genus diversity estimators for 16s rRNA amplicons from Manzanilla and Gordal samples at the post-fermentation stage; Table S2: Number of reads and genus diversity estimators for ITS amplicons from Manzanilla and Gordal samples at the post-fermentation stage; Table S3: [PERSON]'s correlation coefficients between the mean values of the relative abundance of microorganisms and the sensory spoilage descriptors; Table S4: [PERSON]'s correlation coefficients between bacterial communities and metabolites; Table S5: [PERSON]'s correlation coefficients between yeast communities and metabolites; Figure S1: Concentrations of lactic and acetic acids in brine samples after 7 and 11 months of brining. Error bars denote standard deviations of triplicate analyses; Figure S2: Total contents of volatile acids and phenols in brine samples. Error bars indicate 95% confidence intervals; Figure S3: Dendrogram of (a) the observations (samples), and (b) variables (metabolites) from the chemical data obtained from agglomerative hierarchical cluster (AHC) analysis; Figure S4: Plot of VIPs (sorted in descending order) with jack-knife uncertainty bars (95%) from the PLS regression between: (a) volatile metabolites and butyric descriptor, and (b) volatile metabolites and zapatera descriptor.