Modeling of Growth and Organic Acid Kinetics and Evolution of the Protein Profile and Amino Acid Content during Lactiplantibacillus plantarum ITM21B Fermentation in Liquid Sourdough.

The application of mathematical modeling to study and characterize lactic acid bacterial strains with pro-technological and functional features has gained attention in recent years to solve the problems relevant to the variabilities of the fermentation processes of sourdough. Since the key factors contributing to the sourdough quality are relevant to the starter strain growth and its metabolic activity, in this study, the cardinal growth parameters for pH, temperature (T), water activity (aw), and undissociated lactic acid of the sourdough strain Lactiplantibacillus plantarum ITM21B, were determined. The strain growth, pH, organic acids (lactic, acetic, phenyllactic, and hydroxy-phenyllactic), total free amino acids, and proteins were monitored during fermentation of a liquid sourdough based on wheat flour and gluten (Bio21B) after changing the starting T, pH, and inoculum load. Results demonstrated that the different fermentation conditions affected the strain growth and metabolite pattern. The organic acid production and growth performance were modeled in Bio21B, and the resulting predictive model allowed us to simulate in silico the strain performances in liquid sourdough under different scenarios. This mathematical predictive approach can be useful to optimize the fermentation conditions needed to obtain the suitable nutritional and technological characteristics of the L. plantarum ITM21B liquid sourdough.

A Predictive Growth Model for Pro-technological and Probiotic Lacticaseibacillus paracasei Strains Fermenting White Cabbage.

Bacterial strains belonging to Lacticaseibacillus paracasei species are generally used as starters in food fermentations and/or as probiotics. In the current study, the growth cardinal parameters of four L. paracasei strains (IMPC2.1, IMPC4.1, P40 and P101), isolated from table olives or human source, were determined. Strains were grown in liquid medium and incubated at several temperatures (10 values from 5.5°C-40°C) and pH (15 values from 3.2 to 9.1) along the growth range. The cardinal temperature model was used to describe temperature effects on the maximum specific growth rate of L. paracasei whereas new equations were developed for the effect of pH. The estimated Tmin values ranged between -0.97°C and 1.95°C and were lower than 0°C for strains IMPC4.1 and P101. Strain P40 was able to grow in the most restricted range of temperature (from 1.95°C to 37.46°C), while strain IMPC4.1 was estimated to survive at extreme conditions showing the lowest pHmin . Maximum specific growth rates of L. paracasei IMPC2.1 in white cabbage (Brassica oleracea var. capitata) were used to calculate the correction factor (Cf ) defined as the bias between the bacterial maximum specific growth rate in broth and in the food matrix. A simple bi-linear model was also developed for the effect of temperature on the maximum population density reached in white cabbage. This information was further used to simulate the growth of L. paracasei strains in cabbage and predict the time to reach the targeted probiotic level (7 log10 CFU/g) using in silico simulations. This study demonstrates the potential of the predictive microbiology to predict the growth of beneficial and pro-technological strains in foods in order to optimize the fermentative process.

Effect of Amaranth and Quinoa Flours on Exopolysaccharide Production and Protein Profile of Liquid Sourdough Fermented by Weissella cibaria and Lactobacillus plantarum.

Exopolysaccharides (EPSs) are known for their positive contribute to the technological properties of many foods, including bakery products. These molecules can be obtained performing piloted fermentation with lactic acid bacteria (LAB). In order to select strains able to produce EPS, a screening test in agar medium containing sucrose, fructose or glucose as carbohydrate source was performed on 21 LAB strains. Results allowed to select 8 Weissella cibaria, 2 Weissella confusa, and 2 Leuconostoc spp. strains as EPS producers only in the presence of sucrose. A further screening in liquid medium enriched with sucrose (10%) (mMRS_S) indicated the W. cibaria strain C43-11 as the higher EPS producer. The selected strain was used to develop liquid sourdoughs (LSs) with dough yield (DY) 500, fermented for 15 h and based on wheat flour and wheat gluten or pseudocereals (quinoa or amaranth) in ratio 1:1, in the presence or not of sucrose at 3% (w/w, LS weight), in comparison to Lactobacillus plantarum ITM21B, a strain not producing EPS in mMRS_S. Results indicated that the use of pseudocereals favored the EPS production. Formulations were optimized by modifying DY (500 or 250), sucrose concentration (3 or 6%) and flour ratio. LSs were characterized for the content of organic acids (lactic, acetic, phenyllactic, OH-phenyllactic), pH, TTA, EPS, viscosity, total protein degradation and protein pattern. The highest EPS production (20.79 g/kg) and viscosity (1168 mPa s) were obtained in LS (DY 250, sucrose 6%) based on quinoa flour and started with C43-11 strain. The LS was characterized by the presence of phenyllactic and OH-phenyllactic acids, protein degradation by 51.7% and proteins in the range 14-80 kDa. In these conditions, also strain ITM21B was able to produce EPS at level of 4.61 g/kg and to degrade proteins by 53.8% in LS based on wheat and quinoa flours (1:1) (DY250 and sucrose 3%). Therefore, results demonstrated that the use of selected conditions (flour type, DY, sucrose) can stimulate specific attributes of strains making them suitable for production of short fermented (15 h) LSs which can be used as bread improvers.

Use of a Selected Leuconostoc Citreum Strain as a Starter for Making a "Yeast-Free" Bread.

The aim of this study was the characterization and selection of bacterial strains suitable for the production of a "yeast-free" bread. The strains Leuconostoc citreum C2.27 and Weissella confusa C5.7 were selected for their leavening and acidification capabilities and individually used as starters in bread-making tests. Liquid type-II sourdoughs, singly inoculated with the two selected strains, were characterized and employed for bread-making, through the set-up of a biotechnological protocol without the use of baker's yeast as a leavening agent. Aiming to verify the ability of the selected strains to dominate the fermentation process, bacteria and yeasts were isolated from liquid sourdoughs and doughs, genetically characterized and identified. Both the selected strains were suitable for the production of bread, even if L. citreum C2.27 showed the highest leavening capacity and was able to dominate the dough microbiota. The effects of different salt concentrations on the selected strain performances were also investigated. The applicability of the developed protocol, adapted for the production of the typical Apulian bread, "puccia", and the suitability of the strain L. citreum C2.27 were confirmed at pilot scale in an industrial bakery. The puccia bread, which was produced with the liquid sourdough fermented with L. citreum C2.27, without baker's yeast and salt, was similar in appearance to the conventional product containing baker's yeast and was judged positively by a sensory analysis.

Quality of ready-to-eat swordfish fillets inoculated with Lactobacillus paracasei IMPC 2.1.

BACKGROUND: The quality of marinated ready-to-eat (RTE) swordfish fillets, with or without inoculation with the probiotic strain Lactobacillus paracasei IMPC 2.1, was assessed over 3 months of refrigerated storage at 4 °C. RTE probiotic and control fish fillets were sampled after 7, 14, 30, 60, and 90 days of storage. Microbiological tests were performed, and fatty acid (FA) profiles and malondialdehyde content were examined. Microbiological counts, including total viable count, lactic acid bacteria (LAB), yeasts, moulds, Enterobacteriaceae, and Pseudomonadaceae were determined. RESULTS: Inoculation successfully ensured the growth of the probiotic strain and prevented the growth of other LAB. The two RTE products showed significant differences in lipid profile and lipid oxidation during storage. In particular, inoculation with L. paracasei IMPC 2.1 increased the amount of polyunsaturated FAs and limited the amount of monounsaturated FAs and oleic acid, as well as lipid oxidation. It thus represents an interesting strategy for preserving the chemical quality of fish fillets and an alternative means of delivering probiotics. CONCLUSION: Probiotic inoculation with Lactobacillus paracasei seemed to delay lipid oxidation of the fish flesh and increase the retention of polyunsaturated FAs, suggesting a potential application for this strain in the seafood industry. © 2018 Society of Chemical Industry.

Bioprotection of ready-to-eat probiotic artichokes processed with Lactobacillus paracasei LMGP22043 against foodborne pathogens.

The survival of 3 pathogens Listeria monocytogenes ATCC19115, Salmonella enterica subsp. enterica ATCC13311, and Escherichia coli ATCC8739 was evaluated over time in ready-to-eat (RTE) artichoke products processed or not with the probiotic strain Lactobacillus paracasei LMGP22043. Both probiotic and standard products (final pH about 4.0; aw = 0.98) dressed with oil and packaged in modified atmosphere were inoculated with pathogens at a level of about 3 log CFU/g and stored at 4 ºC for 45 d. Pathogens decreased in the probiotic product in 2 descent phases, without shoulder and/or tailing as observed by fitting the models available in the GInaFit software to the experimental data. S. enterica subsp. enterica was completely inactivated after 14 and 28 d in probiotic and standard products, respectively; E. coli was inhibited in the probiotic food at day 4 (count

An Rhs-like genetic element is involved in bacteriocin production by Pseudomonas savastanoi pv. savastanoi.

The main aim of this work was the identification of genetic determinants involved in bacteriocin production by strain ITM317 of Pseudomonas savastanoi pv. savastanoi, besides bacteriocin characterization. The bacteriocin was observed to be a heat-sensitive, high molecular weight proteinaceous compound. We identified a transposon (Tn5)-induced mutant which had lost its ability to produce the bacteriocin. The Tn5 insertion's responsibility for the above mutated phenotype was demonstrated by marker-exchange mutagenesis. An EcoRI DNA fragment, corresponding to the EcoRI Tn5-containing fragment of the mutant, was also cloned from the wild-type strain, and its introduction into the mutant complemented the mutation. Moreover, that fragment enabled bacteriocin production by P. s. pv. savastanoi ITM302, a strain not previously capable of doing so. DNA sequence analysis revealed that Tn5 insertion occurred in the mutant within a large ORF encoding a protein which showed similarity with proteins from the Rhs family. The DNA region including that ORF showed features which have been considered typical of the Rhs genetic elements previously identified in other bacteria but whose function is as yet unclear. The results of this study for the first time identify an Rhs-like element in P. s. pv. savastanoi, and for the first time indicate that an Rhs element is involved in bacteriocin production, also suggesting this possible function for Rhs genetic elements previously characterized in other bacteria.

Effects of probiotic Lactobacillus paracasei-enriched artichokes on constipated patients: a pilot study.

GOALS: To determine whether the consumption of artichokes enriched with a probiotic Lactobacillus paracasei strain affects fecal microbiota composition, fecal enzyme activity, and short-chain fatty acids production and symptom profile in patients suffering from constipation. BACKGROUND: Constipation is a common gastrointestinal disorder often related to the food diet. The beneficial effects of probiotics and prebiotics on human health are under investigation. Moreover, recent studies assessed the suitability of some vegetables, particularly olives and artichokes, to vehicle probiotic strains into the gastrointestinal tract. STUDY: For 15 days, 8 volunteers (3M/5F age 40+/-14 y) integrated their normal diet with artichokes (180 gr) enriched with 20 billions of L. paracasei LMGP22043. Faecal samples were subjected to microbiologic and biochemical analyses. Besides, investigations on symptom profile of the volunteers and stool consistency were carried out by using a validated questionnaire (Gastrointestinal Symptom Rating Scale) and the Bristol stool form chart. RESULTS: The gut of all volunteers resulted to be colonized by the probiotic strain after 15 days feeding. No significant differences in the microbiological counts throughout the experimental period were registered, whereas a significant increase of butyric and valeric acids with a concomitant decrease of lactic acid was registered. At the same time, the fecal beta-glucuronidase activity was significantly reduced. Finally, the analysis of symptom profile indicated a marked reduction in abdominal distension and feeling of incomplete evacuation. CONCLUSIONS: These preliminary data suggest that novel approaches for treating constipation can come through ingestion of probiotic vegetable products that, acting as symbiotics, can ameliorate this common disorder.

Probiotic table olives: microbial populations adhering on olive surface in fermentation sets inoculated with the probiotic strain Lactobacillus paracasei IMPC2.1 in an industrial plant.

This study reports the dynamics of microbial populations adhering on the surface of debittered green olives cv. Bella di Cerignola in fermentation sets inoculated with the probiotic strain Lactobacillus paracasei IMPC2.1 in different brining conditions (4% and 8% (w/v) NaCl) at room temperature and 4 degrees C. The probiotic strain successfully colonized the olive surface dominating the natural LAB population and decreasing the pH of brines to

In vitro and in vivo survival and transit tolerance of potentially probiotic strains carried by artichokes in the gastrointestinal tract.

The ability of potentially probiotic strains of Lactobacillus plantarum and Lactobacillus paracasei to survive on artichokes for at least 90 days was shown. The anchorage of bacterial strains to artichokes improved their survival in simulated gastrointestinal digestion. L. paracasei IMPC2.1 was further used in an artichoke human feeding study involving four volunteers, and it was shown that the organism could be recovered from stools.

Study of adhesion and survival of lactobacilli and bifidobacteria on table olives with the aim of formulating a new probiotic food.

With the aim of developing new functional foods, a traditional product, the table olive, was used as a vehicle for incorporating probiotic bacterial species. Survival on table olives of Lactobacillus rhamnosus (three strains), Lactobacillus paracasei (two strains), Bifidobacterium bifidum (one strain), and Bifidobacterium longum (one strain) at room temperature was investigated. The results obtained using a selected olive sample demonstrated that bifidobacteria and one strain of L. rhamnosus (Lactobacillus GG) showed a good survival rate, with a recovery of about 10(6) CFU g(-1) after 30 days. The Lactobacillus GG population remained unvaried until the end of the experiment, while a slight decline (to about 10(5) CFU g(-1)) was observed for bifidobacteria. High viability, with more than 10(7) CFU g(-1), was observed throughout the 3-month experiment for L. paracasei IMPC2.1. This strain, selected for its potential probiotic characteristics and for its lengthy survival on olives, was used to validate table olives as a carrier for transporting bacterial cells into the human gastrointestinal tract. L. paracasei IMPC2.1 was recovered from fecal samples in four out of five volunteers fed 10 to 15 olives per day carrying about 10(9) to 10(10) viable cells for 10 days.

Reduction of olive knot disease by a bacteriocin from Pseudomonas syringae pv. ciccaronei.

A bacteriocin produced by Pseudomonas syringae pv. ciccaronei, used at different purification levels and concentrations in culture and in planta, inhibited the multiplication of P. syringae subsp. savastanoi, the causal agent of olive knot disease, and affected the epiphytic survival of the pathogen on the leaves and twigs of treated olive plants. Treatments with bacteriocin from P. syringae pv. ciccaronei inhibited the formation of overgrowths on olive plants caused by P. syringae subsp. savastanoi strains PVBa229 and PVBa304 inoculated on V-shaped slits and on leaf scars at concentrations of 10(5) and 10(8) CFU ml(-1), respectively. In particular, the application of 6,000 arbitrary units (AU) of crude bacteriocin (dialyzed ammonium sulfate precipitate of culture supernatant) ml(-1) at the inoculated V-shaped slits and leaf scars resulted in the formation of knots with weight values reduced by 81 and 51%, respectively, compared to the control, depending on the strains and inoculation method used. Crude bacteriocin (6,000 AU ml(-1)) was also effective in controlling the multiplication of epiphytic populations of the pathogen. In particular, the bacterial populations recovered after 30 days were at least 350 and 20 times lower than the control populations on twigs and on leaves, respectively. These results suggest that bacteriocin from P. syringae pv. ciccaronei can be used effectively to control the survival of the causal agent of olive knot disease and to prevent its multiplication at inoculation sites.