Formation and Characterization of Early Bacterial Biofilms on Different Wood Typologies Applied in Dairy Production

Abstract

The main hypothesis of this work was that Sicilian forestry resources are suitable for the production of equipment to be used in cheese making and indigenous milk lactic acid bacteria (LAB) are able to develop stable biofilms providing starter and nonstarter cultures necessary for curd fermentation and cheese ripening, respectively. Hence, the present work was carried out with deproteinized whey to evaluate LAB biofilm formation on different woods derived from tree species grown in Sicily. Microbiological and scanning electron microscopy analyses showed minimal differences in microbial levels and compositions for the neoformed biofilms. The specific investigation of spp.,, , coagulase-positive staphylococci (CPS), and sulfite-reducing anaerobes did not generate any colony for all vats before and after bacterial adhesion. LAB populations dominated all vat surfaces. The highest levels (7.63 log CFU/cm) were registered for thermophilic cocci. Different colonies were characterized physiologically, biochemically, and genetically (at strain and species levels). Six species within the genera ,, , and were identified. The species most frequently present were and LAB found on the surfaces of the wooden vats in this study showed interesting characteristics important for dairy manufacture. To thoroughly investigate the safety of the wooden vat, a test of artificial contamination on new Calabrian chestnut (control wood) vats was carried out. The results showed that LAB represent efficient barriers to the adhesion of the main dairy pathogens, probably due to their acidity and bacteriocin generation. This study highlights the importance of using wooden vats for traditional cheese production and provides evidence for the valorization of the Sicilian forest wood resources via the production of dairy equipment.

Microbial Community Structure and Diversity of Shrimp Paste at Different Fermentation Stages

“…Several previous studies have focused on naturally fermented foods, including artisanal cheeses (46), Chinese liquor (47), and dairy products (48–49). In addition, there has been some research into the microbial diversity of shrimp culture environments, and the chemical composition and sensory attributes of shrimp paste [50].…”

Antimicrobial Characteristics of Untreated Wood: Towards a Hygienic Environment

“…In a similar study no inhibitory compounds by biofilm microflora were observed [49]. Therefore this reduction in L. monocytogenes numbers can be attributed to "Jameson effect" according to the nutrient consumption and exhaustion by competitive microorganisms [49] [60] [61]. This type of effect can be used on wood for treatment with probiotic type microorganisms and their bio-surfactants, which may antagonize the growth of nosocomial pathogens on inanimate surfaces [62].…”

“…Mariani et al [59] (CFU/cm 2 ) when the resident biofilm was thermally inactivated, suggesting a microbial origin of the observed inhibitory effect. In a similar study no inhibitory compounds by biofilm microflora were observed [49]. Therefore this reduction in L. monocytogenes numbers can be attributed to "Jameson effect" according to the nutrient consumption and exhaustion by competitive microorganisms [49] [60] [61].…”

“…Once the biofilm was formed, they are difficult to clean and disinfect on surfaces, and the microbial transfer from cutting boards to cucumbers was also highest in wood. However, in cheese making process, the presence of lactic acid bacteria counters the adherence of many pathogens including Listeria spp., Salmonella and other enterobacteriaceae [49] [50].…”

Shelf life evaluation of fresh-cut red chicory subjected to different minimal processes

“…Different microbial groups were investigated as follows: total mesophilic microorganisms (TMM) and total psychrotrophic microorganisms (TPM) on plate count agar PCA; pseudomonads on Pseudomonas agar base (PAB) added with CFC supplement; members of the Enterobacteriaceae family on double-layered violet red bile glucose agar (VRBGA); total coliforms on double-layered violet red bile agar (VRBA); enterococci on kanamycin aesculin azide (KAA) agar; coagulase-positive and coagulase-negative staphylococci (CPS and CNS) on Baird Parker (BP) added with RPF supplement; L. monocytogenes on Listeria selective agar base (LSAB) added with SR0140E supplement; yeasts on yeast extract peptone dextrose (YPD) agar supplemented with 0.1 g/L chloramphenicol to avoid bacterial growth. The incubation conditions are described in Cruciata et al (2018). All media and supplements were purchased from Oxoid (Milan, Italy).…”