title: Monitoring of wheat lactic acid bacteria from the field until the first step of dough fermentation.
abstract: The present work was carried out to retrieve the origin of lactic acid bacteria (LAB) in sourdough. To this purpose, wheat LAB were monitored from ear harvest until the first step of fermentation for sourdough development. The influence of the geographical area and variety on LAB species/strain composition was also determined. The ears of four Triticum durum varieties (Duilio, Iride, Saragolla and Simeto) were collected from several fields located within the Palermo province (Sicily, Italy) and microbiologically investigated. In order to trace the transfer of LAB during the consecutive steps of manipulation, ears were transformed aseptically and, after threshing, milling and fermentation, samples of kernels, semolinas and doughs, respectively, were analysed. LAB were not found to dominate the microbial communities of the raw materials. In general, kernels harboured lower levels of microorganisms than ears and ears than semolinas. Several samples showing no development of LAB colonies acidified the enrichment broth suggesting the presence of LAB below the detection limit. After fermentation, LAB loads increased consistently for all doughs, reaching levels of 7.0-7.5 Log CFU/g on M17. The values of pH (5.0) and TTA (5.6 mL NaOH/10 g of dough) indicated the occurrence of the acidification process for several doughs. LAB were phenotypically and genotypically differentiated by randomly amplified polymorphic DNA (RAPD)-PCR into eight groups including 51 strains belonging to the species Lactobacillus brevis, Lactobacillus coryniformis, Lactobacillus plantarum, Lactococcus lactis, Lactococcus garvieae, Enterococcus casseliflavus, Enterococcus faecium, Leuconostoc citreum, and Pediococcus pentosaceus. Lactobacilli constituted a minority the LAB community, while lactococci represented more than 50% of strains. Lower LAB complexity was found on kernels, while a richer biodiversity was observed in semolinas and fermented doughs. For broader microbiota characterisation in doughs before fermentation, the 16S rRNA gene fragment profiling was conducted on the unfermented doughs using MiSeq Illumina. LAB group was represented by Enterococcus, Lactococcus and members of Leuconostocaceae family whose relative abundances differed according to both geographical area and variety of wheat. The culture-independent approach confirmed that pediococci and lactobacilli constituted low abundance members of the semolina LAB microbiota and that although some strains may pass from wheat ear to fermented doughs, most are likely to come from other sources.
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università di Palermo, Viale delle Scienze 4, 90128 Palermo, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Alfonzo
authors.affiliation: Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria - Centro di Sperimentazione e certificazione delle sementi (CREA - SCS) Sede di Palermo, Viale Regione Siciliana s-e, 8669, 90121 Palermo, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Miceli
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università di Palermo, Viale delle Scienze 4, 90128 Palermo, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Nasca
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, San Michele all'Adige, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Franciosi
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università di Palermo, Viale delle Scienze 4, 90128 Palermo, Italy.
authors.forename: Giusi
authors.initials: G
authors.lastname: Ventimiglia
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università di Palermo, Viale delle Scienze 4, 90128 Palermo, Italy.
authors.forename: Rosalia
authors.initials: R
authors.lastname: Di Gerlando
authors.affiliation: Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, San Michele all'Adige, Italy.
authors.forename: Kieran
authors.initials: K
authors.lastname: Tuohy
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università di Palermo, Viale delle Scienze 4, 90128 Palermo, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Francesca
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università di Palermo, Viale delle Scienze 4, 90128 Palermo, Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Moschetti
authors.affiliation: Dipartimento Scienze Agrarie e Forestali, Università di Palermo, Viale delle Scienze 4, 90128 Palermo, Italy. Electronic address: luca.settanni@unipa.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Settanni
mesh_terms: D058491:Bacterial Load; D044822:Biodiversity; D001939:Bread / Q000032:analysis / Q000382:microbiology; D005285:Fermentation; D005433:Flour / Q000032:analysis / Q000382:microbiology*; D005516:Food Microbiology; D005838:Genotype; D007558:Italy; D056546:Lactobacillales / Q000235:genetics / Q000302:isolation & purification*; D007778:Lactobacillus / Q000235:genetics / Q000302:isolation & purification; D007934:Leuconostoc / Q000235:genetics / Q000302:isolation & purification; D010376:Pediococcus / Q000235:genetics / Q000302:isolation & purification; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique; D014908:Triticum / Q000033:anatomy & histology / Q000382:microbiology*
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: Ears; Kernels; Lactic acid bacteria; MiSeq Illumina; Semolina; Sourdough; Wheat