Selenium-enriched fermented beverage with improved sensorial properties using lactic acid bacteria.

The aim of this study was to formulate a Selenium (Se)-bioenriched fermented beverage using selenized lactic acid bacteria (LAB) with desirable sensory attributes and shelf-life. The fruit-origin strains Lactiplantibacillus paraplantarum CRL 2051 and Fructobacillus tropaeoli CRL 2034 were grown in MRS-fructose with 5 mg/L Se before inoculation. Then, the selenized strains were inoculated separately or together in a fruit juice and cowmilk beverage and allowed to ferment at 30 °C for 14 h. During microbial growth, the strains accumulated 62.8-93.5 µg/L of total Se, with 32.7-47.8 µg/L composed of the amino acids selenocysteine (SeCys), and 6.1-12.7 µg/L of selenomethionine (SeMet). The beverages fermented by L. paraplantarum CRL 2051 alone and by the mixed culture showed the highest levels of general acceptance and best sensory attributes. The latter fermented beverage exhibited high microbial resistance to cold storage after 52 days and to gastrointestinal tract conditions as well as an acceptable sensory shelf-life of 42 days. For the first time, microbial selenization previous to food fermentation successfully allowed Se fortification and the formulation of a functional Se-enriched beverage with desirable sensory properties and shelf-life. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-024-05984-4.

Fermented pomegranate juice enriched with pomegranate seed oil ameliorates metabolic disorders associated with a high-fat diet in C57BL/6 mice.

This study investigated the health-functional properties of a lactic fermented pomegranate juice (FPJ) enriched with pomegranate seed oil (FPJO) by using the fruit-origin strain Lactiplantibacillus paraplantarum CRL 2051 (FPJO-CRL2051). For this aim, the in vitro human antiplatelet aggregation effect and antioxidant activities were determined in the fermented juices while in vivo studies using high-fat-diet (HFD) C57BL/6 mice fed with a high-fat diet or pomegranate fermented juices for 8 weeks were performed. A high anti-platelet aggregation activity for FPJO-CRL2051 was determined. The formulated juice was administered to C57BL/6 HFD mice over 8 weeks, which showed a significant decrease in triglycerides, LDL-C, and pro-inflammatory cytokines levels. The FPJO-CRL2051 administration was effective in ameliorating liver damage caused by HFD, reducing fat accumulation and oxidative biomarkers, and improving the liver fatty acid profile by incorporation of conjugated fatty acids. This study shows the significance of lactic fermentation in developing novel fermented plant-based beverages with enhanced functional activities with a circular economy approach for the prevention of metabolic disorders.

Genomic diversity in Fructobacillus spp. isolated from fructose-rich niches.

The Fructobacillus genus is a group of obligately fructophilic lactic acid bacteria (FLAB) that requires the use of fructose or another electron acceptor for their growth. In this work, we performed a comparative genomic analysis within the genus Fructobacillus by using 24 available genomes to evaluate genomic and metabolic differences among these organisms. In the genome of these strains, which varies between 1.15- and 1.75-Mbp, nineteen intact prophage regions, and seven complete CRISPR-Cas type II systems were found. Phylogenetic analyses located the studied genomes in two different clades. A pangenome analysis and a functional classification of their genes revealed that genomes of the first clade presented fewer genes involved in the synthesis of amino acids and other nitrogen compounds. Moreover, the presence of genes strictly related to the use of fructose and electron acceptors was variable within the genus, although these variations were not always related to the phylogeny.

Selenium stress response of the fruit origin strain Fructobacillus tropaeoli CRL 2034.

The fruit-origin strain Fructobacillus tropaeoli CRL 2034 can biotransform selenium into seleno-nanoparticles and selenocysteine. The proteomic analysis of F. tropaeoli CRL 2034 exposed to 5 and 100 ppm of Se showed a dose-dependent response since 19 and 77 proteins were deregulated, respectively. In the presence of 5 ppm of Se, the deregulated proteins mainly belonged to the categories of energy production and conversion or had unknown functions, while when cells were grown with 100 ppm of Se, most of the proteins were grouped into amino acid transport and metabolism, nucleotide transport and metabolism, or into unknown functions. However, under both Se conditions, glutathione reductases were overexpressed (1.8-3.1-fold), while mannitol 2-dehydrogenase was downregulated (0.54-0.19-fold), both enzymes related to oxidative stress functions. Mannitol 2-dehydrogenase was the only enzyme found that contained SeCys, and its activity was 1.27-fold increased after 5 ppm of Se exposure. Our results suggest that F. tropaeoli CRL 2034 counteracts Se stress by overexpressing proteins related to oxidative stress resistance and changing the membrane hydrophobicity, which may improve its survival under (food) storage and positively influence its adhesion to intestinal cells. Selenized cells of F. tropaeoli CRL 2034 could be used for producing Se-enriched fermented foods. KEY POINTS: • Selenized cells of F. tropaeoli showed enhanced resistance to oxidative stress. • SeCys was found in the Fructobacillus mannitol 2-dehydrogenase polypeptide chain. • F. tropaeoli mannitol 2-dehydrogenase activity was highest when exposed to selenium.

Microbiomes Associated With the Surfaces of Northern Argentinian Fruits Show a Wide Species Diversity.

The fiber, vitamin, and antioxidant contents of fruits contribute to a balanced human diet. In countries such as Argentina, several tropical fruits are witnessing a high yield in the harvest season, with a resulting surplus. Fruit fermentation using autochthonous starter cultures can provide a solution for food waste. However, limited knowledge exists about the microbiota present on the surfaces of fruits and the preceding flowers. In the present exploratory study, the microbiomes associated with the surfaces of tropical fruits from Northern Argentina, such as white guava, passion fruit and papaya were investigated using a shotgun metagenomic sequencing approach. Hereto, one sample composed of 14 white guava fruits, two samples of passion fruits with each two to three fruits representing the almost ripe and ripe stage of maturity, four samples of papaya with each two to three fruits representing the unripe, almost ripe, and ripe stage of maturity were processed, as well as a sample of closed and a sample of open Japanese medlar flowers. A considerable heterogeneity was found in the composition of the fruits' surface microbiota at the genus and species level. While bacteria dominated the microbiota of the fruits and flowers, a small number of the metagenomic sequence reads corresponded with yeasts and filamentous fungi. A minimal abundance of bacterial species critical in lactic acid and acetic acid fermentations was found. A considerable fraction of the metagenomic sequence reads from the fruits' surface microbiomes remained unidentified, which suggested that intrinsic species are to be sequenced or discovered.

Functional fermented cherimoya (Annona cherimola Mill.) juice using autochthonous lactic acid bacteria.

The biochemical and functional properties of fermented Annona cherimola Mill. (cherimoya) juice using five lactic acid bacteria (LAB) isolated from autochthonous fruits from Northwestern Argentina were studied in this work. Fermentation was carried out at 30 °C for 48 h followed by a 21 day-storage period at 4 °C. The assayed LAB grew well during fermentation (final count of 108 CFU/mL, ΔpH ca. 1 U) and survived after the storage period. All strains consumed fructose and glucose present in cherimoya juice as energy sources, with the consequent synthesis of lactic and/or acetic acids as final metabolic products. However, only two of the five evaluated strains were capable to produce fermented cherimoya juices with a perceptible color change. Due to lactic acid fermentation, a moderate reduction in the total phenolic content (between 13% and 43%) was observed in the majority of the samples, although no change in the antioxidant capacity was detected. The fermented cherimoya juices showed a weak antiplatelet activity when adenosine diphosphate agonist was used. The findings of this study evidenced the potential use of Annona cherimola Mill. fermented juice as a novel matrix for the formulation of stable functional beverages with appealing nutritional and functional properties.

Exploring the Genome of Fructobacillus tropaeoli CRL 2034, a Fig-Origin Strain that Produces High Levels of Mannitol from Fructose.

We report the draft genome sequence of Fructobacillus tropaeoli CRL 2034, a strain isolated from ripe fig in Tucumán province, Argentina. The interest in studying the genome of this fructophilic lactic acid bacterium strain was motivated by its ability to produce high levels of mannitol from fructose. This polyol has multiple industrial applications; however, it is mainly used as low calorie sugar in the food industry. The assembled genome of this strain consists of a 1.66-Mbp circular chromosome with 1465 coding sequences and a G+C content of 44.6%. The analysis of this genome supports the one step reaction of fructose reduction to mannitol by the mannitol 2-dehydrogenase enzyme, which together with a fructose permease, were identified as involved in mannitol synthesis. In addition, a phylogenetic analysis was performed including other Leuconostocaceae members to which the Fructobacillus genus belongs to; according to the 16S rRNA gene sequences, the strain CRL 2034 was located in the Fructobacillus clade. The present genome sequence could be useful to further elucidate regulatory processes of mannitol and other bioactive metabolites and to highlight the biotechnological potential of this fruit-origin Fructobacillus strain.

Major role of lactate dehydrogenase D-LDH1 for the synthesis of lactic acid in Fructobacillus tropaeoli CRL 2034.

The enzymes D- and L-lactate dehydrogenase are involved in the reduction of pyruvate to D(+)- and L(-)-lactate, respectively. The fig-origin strain Fructobacillus tropaeoli CRL 2034 produces D- and L-lactic acids in a 9:1 ratio. In this work, two D-ldh (ldh1 and ldh2) and one L-ldh (ldh3) genes were found in the CRL 2034 genome. ldh1 and ldh2 are homologous (79% identity) and organized as contiguous operons, each gene containing 996 base pair (bp) and encoding for a 331-amino acid (aa) protein (74% identity). In contrast, ldh3 is a 927-bp gene coding for a 308-aa protein. The identity between ldh1/ldh2 and ldh3 was lower than 48%. To elucidate the role of these genes in the synthesis of lactic acid by the Fructobacillus strain, plasmid insertion mutants in each gene were generated and characterized. The growth kinetic parameters were affected only in CRL2034 ldh1::pRV300 cells, this mutant showing the lowest total lactic acid production (4.50 ± 0.15 versus 6.36 ± 0.67 g/L of wild-type strain), with a D/L ratio of 7.1:2.9. These results showed that the ldh1 gene is primarily responsible for lactic acid production by the studied strain. A comparative analysis among strains of the five Fructobacillus species revealed that the identity of D-LDH proteins was higher than 70%, while the identity of L-LDH was over 60%. Finally, phylogenetic analysis of D- and L-LDHs revealed that only D-LDH phylogeny was consistent to the phylogenetic evolution among Fructobacillus and evolutionarily related genera. Key Points •F. tropaeoli CRL 2034 harbors three ldh genes in its genome. •ldh1 and ldh2 encode D-lactate dehydrogenase; ldh3 encodes L-lactate dehydrogenase. •Gene ldh1 plays the major role in lactic acid production by strain CRL 2034. •Fructobacillus D-LDH phylogeny was consistent to phylogenetic evolution.

Biotransformation of Selenium by Lactic Acid Bacteria: Formation of Seleno-Nanoparticles and Seleno-Amino Acids.

Selenium (Se) is an essential micronutrient for the majority of living organisms, and it has been identified as selenocysteine in the active site of several selenoproteins such as glutathione peroxidase, thioredoxin reductase, and deiodinases. Se deficiency in humans is associated with viral infections, thyroid dysfunction, different types of cancer, and aging. In several European countries as well as in Argentina, Se intake is below the recommended dietary Intake (RDI). Some lactic acid bacteria (LAB) can accumulate and bio-transform selenite (toxic) into Se-nanoparticles (SeNPs) and Se-amino acids (non-toxic). The microbial growth, Se metabolite distribution, and the glutathione reductase (involved in selenite reduction) activity of Se-enriched LAB were studied in this work. The ninety-six assayed strains, belonging to the genera Lactococcus, Weissella, Leuconostoc, Lactobacillus, Enterococcus, and Fructobacillus could grow in the presence of 5 ppm sodium selenite. From the total, eight strains could remove more than 80% of the added Se from the culture medium. These bacteria accumulated intracellularly between 1.2 and 2.5 ppm of the added Se, from which F. tropaeoli CRL 2034 contained the highest intracellular amount. These strains produced only the seleno-amino acid SeCys as observed by LC-ICP-MS and confirmed by LC-ESI-MS/MS. The intracellular SeCys concentrations were between 0.015 and 0.880 ppm; Lb. brevis CRL 2051 (0.873 ppm), Lb. plantarum CRL 2030 (0.867 ppm), and F. tropaeoli CRL 2034 (0.625 ppm) were the strains that showed the highest concentrations. Glutathione reductase activity values were higher when the strains were grown in the presence of Se except for the F. tropaeoli CRL 2034 strain, which showed an opposite behavior. The cellular morphology of the strains was not affected by the presence of Se in the culture medium; interestingly, all the strains were able to form spherical SeNPs as determined by transmission electron microscopy (TEM). Only two Enterococcus strains produced the volatile Se compounds dimethyl-diselenide identified by GC-MS. Our results show that Lb. brevis CRL 2051, Lb. plantarum CRL 2030, and F. tropaeoli CRL 2034 could be used for the development of nutraceuticals or as starter cultures for the bio-enrichment of fermented fruit beverages with SeCys and SeNPs.

Survival of selenium-enriched lactic acid bacteria in a fermented drink under storage and simulated gastro-intestinal digestion.

Selenium (Se), which is present as SeCys in seleno-proteins, is involved in cancer prevention, thyroid functioning, and pathogen inhibition. Se is incorporated in the diet through Se-containing foods. Some lactic acid bacteria (LAB) can biotransform selenite (toxic) into Se-nanoparticles (SeNPs) and Se-amino acids. To exert their beneficial properties in the host, bacteria should survive the harsh conditions of the gastrointestinal tract and during food storage. We evaluated whether selenization of LAB influenced bacterial growth and survival during gastrointestinal digestion and after storage when present in a fermented fruit juice-milk (FJM) beverage. Lactobacillus brevis CRL 2051 and Fructobacillus tropaeoli CRL 2034 were grown in MRS with and without selenite, and used to inoculate the FJM matrix. Selenization had no effect on LAB growth (9.54-9.9 log CFU/mL) in the FJM drink. The presence of SeNPs was confirmed for both selenized strains in the FJM beverage; however, the highest Se concentration (100 µg/L) was detected for the fermented beverage with selenized L. brevis. Under storage conditions 1.1 log CFU/ml decrease in cell count of selenized cells of L. brevis was observed, while no effect on cell viability was detected for non-selenized L. brevis or both selenized and control cells of F. tropaeoli. Resistance of L. brevis during digestion of the fermented FJM beverage was not affected by selenization. Contrarily, an increase (1 log CFU/mL) in the resistance of F. tropaeoli was observed when cells were selenized. After digestion, Se was detected in the soluble fraction of the beverage fermented by both strains, being higher for L. brevis (23.6 µg/L). Although selenization did not exert a drastic effect on strains´ survival during storage and digestion, microbial selenization previous to food fermentation could be an interesting tool for Se enrichment avoiding thus the addition of toxic Se salts.

Diversity and Functional Properties of Lactic Acid Bacteria Isolated From Wild Fruits and Flowers Present in Northern Argentina.

Lactic acid bacteria (LAB) are capable of converting carbohydrate substrates into organic acids (mainly lactic acid) and producing a wide range of metabolites. Due to their interesting beneficial properties, LAB are widely used as starter cultures, as probiotics, and as microbial cell factories. Exploring LAB present in unknown niches may lead to the isolation of unique species or strains with relevant technological properties. Autochthonous rather than allochthonous starter cultures are preferred in the current industry of fermented food products, due to better adaptation and performance of autochthonous strains to the matrix they originate from. In this work, the lactic microbiota of eight different wild tropical types of fruits and four types of flowers were studied. The ability of the isolated strains to produce metabolites of interest to the food industry was evaluated. The presence of 21 species belonging to the genera Enterococcus, Fructobacillus, Lactobacillus, Lactococcus, Leuconostoc, and Weissella was evidenced by using culture-dependent techniques. The isolated LAB corresponded to 95 genotypically differentiated strains by applying rep-PCR and sequencing of the 16S rRNA gene; subsequently, representative strains of the different isolated species were studied for technological properties, such as fast growth rate and acidifying capacity; pectinolytic and cinnamoyl esterase activities, and absence of biogenic amine biosynthesis. Additionally, the strains' capacity to produce ethyl esters as well as mannitol was evaluated. The isolated fruit- and flower-origin LAB displayed functional properties that validate their potential use in the manufacture of fermented fruit-based products setting the background for the design of novel functional foods.

YebC, a putative transcriptional factor involved in the regulation of the proteolytic system of Lactobacillus.

The proteolytic system of Lactobacillus plays an essential role in bacterial growth, contributes to the flavor development of fermented products, and can release bioactive health-beneficial peptides during milk fermentation. In this work, a genomic analysis of all genes involved in the proteolytic system of L. delbrueckii subsp. lactis CRL 581 was performed. Genes encoding the cell envelope-associated proteinase, two peptide transport systems, and sixteen peptidases were identified. The influence of the peptide supply on the transcription of 23 genes involved in the proteolytic system of L. delbrueckii subsp. lactis was examined after cell growth in a chemically defined medium (CDM) and CDM supplemented with Casitone. prtL, oppA 1, optS, optA genes as well as oppDFBC and optBCDF operons were the most highly expressed genes in CDM; their expression being repressed 6- to 115-fold by the addition of peptides. The transcriptional analysis was confirmed by proteomics; the up-regulation of the PrtL, PepG, OppD and OptF proteins in the absence of peptides was observed while the DNA-binding protein YebC was up-regulated by peptides. Binding of YebC to the promoter region of prtL, oppA 1, and optS, demonstrated by electrophoretic mobility shift assays, showed that YebC acts as a transcriptional repressor of key proteolytic genes.

Enhanced mannitol biosynthesis by the fruit origin strain Fructobacillus tropaeoli CRL 2034.

Mannitol is a natural low-calorie sugar alcohol produced by certain (micro)organisms applicable in foods for diabetics due to its zero glycemic index. In this work, we evaluated mannitol production and yield by the fruit origin strain Fructobacillus tropaeoli CRL 2034 using response surface methodology with central composite design (CCD) as optimization strategy. The effect of the total saccharide (glucose + fructose, 1:2) content (TSC) in the medium (75, 100, 150, 200, and 225 g/l) and stirring (S; 50, 100, 200, 300 and 350 rpm) on mannitol production and yield by this strain was evaluated by using a 22 full-factorial CCD with 4 axial points (α = 1.5) and four replications of the center point, leading to 12 random experimental runs. Fermentations were carried out at 30 °C and pH 5.0 for 24 h. Minitab-15 software was used for experimental design and data analyses. The multiple response prediction analysis established 165 g/l of TSC and 200 rpm of S as optimal culture conditions to reach 85.03 g/l [95% CI (78.68, 91.39)] of mannitol and a yield of 82.02% [95% CI (71.98, 92.06)]. Finally, a validation experiment was conducted at the predicted optimum levels. The results obtained were 81.91 g/l of mannitol with a yield of 77.47% in outstanding agreement with the expected values. The mannitol 2-dehydrogenase enzyme activity was determined with 4.6-4.9 U/mg as the highest value found. To conclude, F. tropaeoli CRL 2034 produced high amounts of high-quality mannitol from fructose, being an excellent candidate for this polyol production.

Global Analysis of Mannitol 2-Dehydrogenase in Lactobacillus reuteri CRL 1101 during Mannitol Production through Enzymatic, Genetic and Proteomic Approaches.

Several plants, fungi, algae, and certain bacteria produce mannitol, a polyol derived from fructose. Mannitol has multiple industrial applications in the food, pharmaceutical, and medical industries, being mainly used as a non-metabolizable sweetener in foods. Many heterofermentative lactic acid bacteria synthesize mannitol when an alternative electron acceptor such as fructose is present in the medium. In previous work, we reported the ability of Lactobacillus reuteri CRL 1101 to efficiently produce mannitol from sugarcane molasses as carbon source at constant pH of 5.0; the activity of the enzyme mannitol 2-dehydrogenase (MDH) responsible for the fructose conversion into mannitol being highest during the log cell growth phase. Here, a detailed assessment of the MDH activity and relative expression of the mdh gene during the growth of L. reuteri CRL 1101 in the presence of fructose is presented. It was observed that MDH was markedly induced by the presence of fructose. A direct correlation between the maximum MDH enzyme activity and a high level of mdh transcript expression during the log-phase of cells grown in a fructose-containing chemically defined medium was detected. Furthermore, two proteomic approaches (2DE and shotgun proteomics) applied in this study confirmed the inducible expression of MDH in L. reuteri. A global study of the effect of fructose on activity, mdh gene, and protein expressions of MDH in L. reuteri is thus for the first time presented. This work represents a deep insight into the polyol formation by a Lactobacillus strain with biotechnological potential in the nutraceutics and pharmaceutical areas.

Whey-derived valuable products obtained by microbial fermentation.

Whey, the main by-product of the cheese industry, is considered as an important pollutant due to its high chemical and biological oxygen demand. Whey, often considered as waste, has high nutritional value and can be used to obtain value-added products, although some of them need expensive enzymatic synthesis. An economical alternative to transform whey into valuable products is through bacterial or yeast fermentations and by accumulation during algae growth. Fermentative processes can be applied either to produce individual compounds or to formulate new foods and beverages. In the first case, a considerable amount of research has been directed to obtain biofuels able to replace those derived from petrol. In addition, the possibility of replacing petrol-derived plastics by biodegradable polymers synthesized during bacterial fermentation of whey has been sought. Further, the ability of different organisms to produce metabolites commonly used in the food and pharmaceutical industries (i.e., lactic acid, lactobionic acid, polysaccharides, etc.) using whey as growth substrate has been studied. On the other hand, new low-cost functional whey-based foods and beverages leveraging the high nutritional quality of whey have been formulated, highlighting the health-promoting effects of fermented whey-derived products. This review aims to gather the multiple uses of whey as sustainable raw material for the production of individual compounds, foods, and beverages by microbial fermentation. This is the first work to give an overview on the microbial transformation of whey as raw material into a large repertoire of industrially relevant foods and products.

Efficient mannitol production by wild-type Lactobacillus reuteri CRL 1101 is attained at constant pH using a simplified culture medium.

Mannitol is a natural polyol with multiple industrial applications. In this work, mannitol production by Lactobacillus reuteri CRL 1101 was studied at free- and controlled-pH (6.0-4.8) fermentations using a simplified culture medium containing yeast and beef extracts and sugarcane molasses. The activity of mannitol 2-dehydrogenase (MDH), the enzyme responsible for mannitol synthesis, was determined. The effect of the initial biomass concentration was further studied. Mannitol production (41.5 ± 1.1 g/l), volumetric productivity (Q Mtl 1.73 ± 0.05 g/l h), and yield (Y Mtl 105 ± 11 %) were maximum at pH 5.0 after 24 h while the highest MDH activity (1.66 ± 0.09 U/mg protein) was obtained at pH 6.0. No correlation between mannitol production and MDH activity was observed when varying the culture pH. The increase (up to 2000-fold) in the initial biomass concentration did not improve mannitol formation after 24 h although a 2-fold higher amount was produced at 8 h using 1 or 2 g cell dry weight/l comparing to the control (0.001 g cell dry weight/l). Finally, mannitol isolation under optimum fermentation conditions was achieved. The mannitol production obtained in this study is the highest reported so far by a wild-type L. reuteri strain and, more interestingly, using a simplified culture medium.

Lactobacillus delbrueckii subsp. bulgaricus CRL 454 cleaves allergenic peptides of ß-lactoglobulin.

Whey, a cheese by-product used as a food additive, is produced worldwide at 40.7 million tons per year. ß-Lactoglobulin (BLG), the main whey protein, is poorly digested and is highly allergenic. We aimed to study the contribution of Lactobacillus delbrueckii subsp. bulgaricus CRL 454 to BLG digestion and to analyse its ability to degrade the main allergenic sequences of this protein. Pre-hydrolysis of BLG by L. delbrueckii subsp. bulgaricus CRL 454 increases digestion of BLG assayed by an in vitro simulated gastrointestinal system. Moreover, peptides from hydrolysis of the allergenic sequences V41-K60, Y102-R124, C121-L140 and L149-I162 were found when BLG was hydrolysed by this strain. Interestingly, peptides possessing antioxidant, ACE inhibitory, antimicrobial and immuno-modulating properties were found in BLG degraded by both the Lactobacillus strain and digestive enzymes. To conclude, pre-hydrolysis of BLG by L. delbrueckii subsp. bulgaricus CRL 454 has a positive effect on BLG digestion and could diminish allergenic reactions.

Draft Genome Sequence of the Mannitol-Producing Strain Lactobacillus mucosae CRL573.

Lactobacillus mucosae CRL573, isolated from child fecal samples, efficiently converts fructose and/or sucrose into the low-calorie sugar mannitol when cultured in modified MRS medium at pH 5.0. Also, the strain is capable of producing bacteriocin. The draft genome sequence of this strain with potential industrial applications is presented here.

Diversity in proteinase specificity of thermophilic lactobacilli as revealed by hydrolysis of dairy and vegetable proteins.

Ability of industrially relevant species of thermophilic lactobacilli strains to hydrolyze proteins from animal (caseins and ß-lactoglobulin) and vegetable (soybean and wheat) sources, as well as influence of peptide content of growth medium on cell envelope-associated proteinase (CEP) activity, was evaluated. Lactobacillus delbrueckii subsp. lactis (CRL 581 and 654), L. delbrueckii subsp. bulgaricus (CRL 454 and 656), Lactobacillus acidophilus (CRL 636 and 1063), and Lactobacillus helveticus (CRL 1062 and 1177) were grown in a chemically defined medium supplemented or not with 1 % Casitone. All strains hydrolyzed mainly ß-casein, while degradation of αs-caseins was strain dependent. Contrariwise, κ-Casein was poorly degraded by the studied lactobacilli. ß-Lactoglobulin was mainly hydrolyzed by CRL 656, CRL 636, and CRL 1062 strains. The L. delbrueckii subsp. lactis strains, L. delbrueckii subsp. bulgaricus CRL 656, and L. helveticus CRL 1177 degraded gliadins in high extent, while the L. acidophilus and L. helveticus strains highly hydrolyzed soy proteins. Proteinase production was inhibited by Casitone, the most affected being the L. delbrueckii subsp. lactis species. This study highlights the importance of proteolytic diversity of lactobacilli for rational strain selection when formulating hydrolyzed dairy or vegetable food products.

Biotechnological and in situ food production of polyols by lactic acid bacteria.

Polyols such as mannitol, erythritol, sorbitol, and xylitol are naturally found in fruits and vegetables and are produced by certain bacteria, fungi, yeasts, and algae. These sugar alcohols are widely used in food and pharmaceutical industries and in medicine because of their interesting physicochemical properties. In the food industry, polyols are employed as natural sweeteners applicable in light and diabetic food products. In the last decade, biotechnological production of polyols by lactic acid bacteria (LAB) has been investigated as an alternative to their current industrial production. While heterofermentative LAB may naturally produce mannitol and erythritol under certain culture conditions, sorbitol and xylitol have been only synthesized through metabolic engineering processes. This review deals with the spontaneous formation of mannitol and erythritol in fermented foods and their biotechnological production by heterofermentative LAB and briefly presented the metabolic engineering processes applied for polyol formation.