A Strategy for the Recovery of Raw Ewe's Milk Microbiodiversity to Develop Natural Starter Cultures for Traditional Foods.

Commercial starter cultures, composed of high concentrations of a few species/strains of lactic acid bacteria (LAB), selected based on their strong technological aptitudes, have been developed to easily and safely carry out food fermentations. Frequently applied to industrial productions, selected starter LAB easily become the dominant microbiota of products, causing a dramatic decrease in biodiversity. On the contrary, natural starter cultures, which usually characterize the most typical and Protected Designation of Origin (PDO) food products, are constituted by a multitude and an indefinite number of LAB species and strains, both starter and nonstarter, thus contributing to preserving microbial biodiversity. However, their use is not risk-free since, if obtained without heat treatment application, natural cultures can contain, together with useful, also spoilage microorganisms or pathogens that could be allowed to multiply during fermentation. In the present study, an innovative method for the production of a natural starter culture directly from raw ewe's milk, inhibiting the growth of spoilage and potentially pathogenic bacteria without applying any heat treatment, was described. The culture developed show a good degree of microbial biodiversity and could be applied to both artisanal and industrial scales, guaranteeing safety, quality constancy, technological performance reproducibility, preserving biodiversity and peculiar sensory characteristics, usually linked to traditional products, while overcoming the problems associated with the daily propagation of natural cultures.

Biodiversity and Safety Assessment of Half-Century Preserved Natural Starter Cultures for Pecorino Romano PDO Cheese.

The use of biodiverse autochthonous natural starter cultures to produce typical and PDO cheeses contributes to establishing a link between products and territory of production, which commercial starters, constituted by few species and strains, are not able to. The purpose of this work was the assessment of biodiversity, at strain level, and safety of natural scotta-innesto cultures whose use is mandatory for the Pecorino Romano PDO cheese manufacturing, according to its product specification. The biodiversity of three scotta-innesto, collected in the 1960s and preserved in lyophilised form, was assessed by molecular biotyping using both PFGE and (GTG)5 rep-PCR profiling on 209 isolates belonging to Streptococcus thermophilus (30), Lactobacillus delbrueckii subsp. lactis (72), Enterococcus faecium (87), and Limosilactobacillus reuteri (20), revealing high biodiversity, at the strain level, in the cultures. The cultures' safety was proved through a new approach assessing phenotypic and molecular antibiotic resistance of the cultures in toto, instead of single strains, while the safety of Enterococcus faecium isolates was investigated according to EFSA guidelines. The use of natural biodiverse cultures for the production of microbial starters for typical and PDO cheeses, such as Pecorino Romano, could be an opportunity for recovering the cheese microbiota biodiversity lost during years of commercial starters use.

Optimization of scotta as growth medium to preserve biodiversity and maximise bacterial cells concentration of natural starter cultures for Pecorino Romano PDO cheese.

Preservation of cheese microbiota biodiversity is central to the sensory quality of traditional and PDO cheeses. Lyophilized commercial selected starters, being advantageous in terms of cells concentration, are supplanting natural cultures causing important loss of microbial biodiversity in the dairy environment. Biodiversity could be recovered using natural starter cultures, however their cells concentration after propagation is lower than the commercial ones. Two autochthonous and biodiverse starter cultures (MixA and MixB) coming from scotta (residual whey from Ricotta cheese manufacture), collected in the 1960 s from Pecorino Romano PDO cheese manufactures, were revitalized in reconstituted commercial powder scotta. The aim of this study was the propagation of the microbial starter mixes increasing their bacterial concentration in the pellet, reducing nonessential scotta components by a fast and not-expensive method, without changing the microbial community balance. The behaviour of each mix inoculated in scotta was compared to that in half-concentrated, clarified, and half-concentrated-clarified scotta. Higher cells concentration in the pellets from the modified scotta was obtained, without changing technological performances and microbial fingerprint. The pellets obtained were reinoculated in commercial scotta for the preparation of the scotta-innesto (the typical starter for Pecorino Romano), and no differences were observed among the treatments after incubation. The reduction of nonessential scotta's components could help the reproduction of natural starter cultures preserving their properties.

Do Best-Selected Strains Perform Table Olive Fermentation Better than Undefined Biodiverse Starters? A Comparative Study.

Twenty-seven Lactobacillus pentosus strains, and the undefined starter for table olives from which they were isolated, were characterised for their technological properties: tolerance to low temperature, high salt concentration, alkaline pH, and olive leaf extract; acidifying ability; oleuropein degradation; hydrogen peroxide and lactic acid production. Two strains with appropriate technological properties were selected. Then, table olive fermentation in vats, with the original starter, the selected strains, and without starter (spontaneous fermentation) were compared. Starters affected some texture profile parameters. The undefined culture resulted in the most effective Enterobacteriaceae reduction, acidification and olive debittering, while the selected strains batch showed the lowest antioxidant activity. Our results show that the best candidate strains cannot guarantee better fermentation performance than the undefined biodiverse mix from which they originate.

Preservation, Characterization and Exploitation of Microbial Biodiversity: The Perspective of the Italian Network of Culture Collections.

Microorganisms represent most of the biodiversity of living organisms in every ecological habitat. They have profound effects on the functioning of any ecosystem, and therefore on the health of our planet and of human beings. Moreover, microorganisms are the main protagonists in food, medical and biotech industries, and have several environmental applications. Accordingly, the characterization and preservation of microbial biodiversity are essential not only for the maintenance of natural ecosystems but also for research purposes and biotechnological exploitation. In this context, culture collections (CCs) and microbial biological resource centres (mBRCs) are crucial for the safeguarding and circulation of biological resources, as well as for the progress of life sciences. This review deals with the expertise and services of CCs, in particular concerning preservation and characterization of microbial resources, by pointing to the advanced approaches applied to investigate a huge reservoir of microorganisms. Data sharing and web services as well as the tight interconnection between CCs and the biotechnological industry are highlighted. In addition, guidelines and regulations related to quality management systems (QMSs), biosafety and biosecurity issues are discussed according to the perspectives of CCs and mBRCs.

Technologies and Trends to Improve Table Olive Quality and Safety.

Table olives are the most widely consumed fermented food in the Mediterranean countries. Peculiar processing technologies are used to process olives, which are aimed at the debittering of the fruits and improvement of their sensory characteristics, ensuring safety of consumption at the same time. Processors demand for novel techniques to improve industrial performances, while consumers' attention for natural and healthy foods has increased in recent years. From field to table, new techniques have been developed to decrease microbial load of potential spoilage microorganisms, improve fermentation kinetics and ensure safety of consumption of the packed products. This review article depicts current technologies and recent advances in the processing technology of table olives. Attention has been paid on pre processing technologies, some of which are still under-researched, expecially physical techniques, such ad ionizing radiations, ultrasounds and electrolyzed water solutions, which are interesting also to ensure pesticide decontamination. The selections and use of starter cultures have been extensively reviewed, particularly the characterization of Lactic Acid Bacteria and Yeasts to fasten and safely drive the fermentation process. The selection and use of probiotic strains to address the request for functional foods has been reported, along with salt reduction strategies to address health concerns, associated with table olives consumption. In this respect, probiotics enriched table olives and strategies to reduce sodium intake are the main topics discussed. New processing technologies and post packaging interventions to extend the shelf life are illustrated, and main findings in modified atmosphere packaging, high pressure processing and biopreservaton applied to table olive, are reported and discussed.

Susceptibility to tetracycline and erythromycin of Lactobacillus paracasei strains isolated from traditional Italian fermented foods.

The aim of this study was to evaluate the susceptibility of 197 isolates of Lactobacillus paracasei, isolated from Italian fermented products coming from different geographical areas, to tetracycline and erythromycin, two antimicrobials widely used in clinical and animal therapy. Isolation media were supplemented with antibiotics according to the microbiological breakpoints (BPs) defined by European Food Safety Authority (EFSA). Isolates were identified at the species level and were typed by rep-PCR using the (GTG)(5) primer. A total of 121 genotypically different strains were detected and their phenotypic antimicrobial resistance to tetracycline and erythromycin was determined as the minimum inhibitory concentration (MIC) using the broth microdilution method. The presence of the genes ermB, ermC and tetL, tetM, tetS, tetW, in the phenotypically resistant isolates was investigated by PCR. Tetracycline induction of tetM expression on representative resistant strains, grown in medium either lacking or containing the antibiotic, was also analyzed by RT-PCR. Among the 121 tested strains, 77.7% were susceptible to tetracycline (MICor=1024 microg/ml) (Erm(R)). The tetM and ermB genes were the most frequently detected in the Tet(R) and/or Erm(R) strains. The tetM expression was induced by antibiotic addition to the growth medium. Our study confirmed that L. paracasei is quite sensitive to tetracycline and erythromycin, but the high level of resistance of Erm(R) strains suggested that acquired resistance took place. Further investigations are required to analyze whether the genes identified in L. paracasei isolates might be horizontally transferred to other species. Since "commensal" bacteria, which L. paracasei belongs to, may play an active role in the spreading of antibiotic resistance, a series of measures inspired from a principle of precaution should be taken before they are used as commercial starters or probiotic cultures in food products, complemented by a more prudent use of antibiotics in agriculture, veterinary, and human medicine.