New Genomic Techniques applied to food cultures: a powerful contribution to innovative, safe, and sustainable food products.

Nontransgenic New Genomic Techniques (NGTs) have emerged as a promising tool for food industries, allowing food cultures to contribute to an innovative, safe, and more sustainable food system. NGTs have the potential to be applied to microorganisms, delivering on challenging performance traits like texture, flavour, and an increase of nutritional value. This paper brings insights on how nontransgenic NGTs applied to food cultures could be beneficial to the sector, enabling food industries to generate innovative, safe, and sustainable products for European consumers. Microorganisms derived from NGTs have the potentials of becoming an important contribution to achieve the ambitious targets set by the European 'Green Deal' and 'Farm to Fork' policies. To encourage the development of NGT-derived microorganisms, the current EU regulatory framework should be adapted. These technologies allow the introduction of a precise, minimal DNA modification in microbial genomes resulting in optimized products carrying features that could also be achieved by spontaneous natural genetic evolution. The possibility to use NGTs as a tool to improve food safety, sustainability, and quality is the bottleneck in food culture developments, as it currently relies on lengthy natural evolution strategies or on untargeted random mutagenesis.

A multifaceted investigation of lactococcal strain diversity in undefined mesophilic starter cultures.

The dairy fermentation industry relies on the activity of lactic acid bacteria in robust starter cultures to accomplish milk acidification. Maintenance of the composition of these starter cultures, whether defined or undefined, is essential to ensure consistent and high-quality fermentation end products. To date, limited information exists regarding the microbial composition of undefined starter culture systems. Here, we describe a culture-based analysis combined with a metagenomics approach to evaluate the composition of two undefined mesophilic starter cultures. In addition, we describe a qPCR-based genotype detection assay, which is capable of discerning nine distinct lactococcal genotypes to characterize these undefined starter cultures, and which can be applied to monitor compositional changes in an undefined starter culture during a fermentation. IMPORTANCE: This study reports on the development of a combined culture-based analysis and metagenomics approach to evaluate the composition of two undefined mesophilic starter cultures. In addition, a novel qPCR-based genotype detection assay, capable of discerning nine distinct lactococcal genotypes (based on lactococcal cell wall polysaccharide biosynthesis gene clusters), was used to monitor compositional changes in an undefined starter culture following phage attack. These analytical approaches facilitate a multifaceted assessment of starter culture compositional stability during milk fermentation, which has become an important QC aspect due to the increasing demand for consistent and high-quality dairy products.

Needle in a Whey-Stack: PhRACS as a Discovery Tool for Unknown Phage-Host Combinations.

The field of metagenomics has rapidly expanded to become the go-to method for complex microbial community analyses. However, there is currently no straightforward route from metagenomics to traditional culture-based methods of strain isolation, particularly in (bacterio)phage biology, leading to an investigative bottleneck. Here, we describe a method that exploits specific phage receptor binding protein (RBP)-host cell surface receptor interaction enabling isolation of phage-host combinations from an environmental sample. The method was successfully applied to two complex sample types-a dairy-derived whey sample and an infant fecal sample, enabling retrieval of specific and culturable phage hosts. IMPORTANCE PhRACS aims to bridge the current divide between in silico genetic analyses (i.e., phageomic studies) and traditional culture-based methodology. Through the labeling of specific bacterial hosts with fluorescently tagged recombinant phage receptor binding proteins and the isolation of tagged cells using flow cytometry, PhRACS allows the full potential of phageomic data to be realized in the wet laboratory.

Bacteriophage-host interactions as a platform to establish the role of phages in modulating the microbial composition of fermented foods.

Food fermentation relies on the activity of robust starter cultures, which are commonly comprised of lactic acid bacteria such as Lactococcus and Streptococcus thermophilus. While bacteriophage infection represents a persistent threat that may cause slowed or failed fermentations, their beneficial role in fermentations is also being appreciated. In order to develop robust starter cultures, it is important to understand how phages interact with and modulate the compositional landscape of these complex microbial communities. Both culture-dependent and -independent methods have been instrumental in defining individual phage-host interactions of many lactic acid bacteria (LAB). This knowledge needs to be integrated and expanded to obtain a full understanding of the overall complexity of such interactions pertinent to fermented foods through a combination of culturomics, metagenomics, and phageomics. With such knowledge, it is believed that factory-specific detection and monitoring systems may be developed to ensure robust and reliable fermentation practices. In this review, we explore/discuss phage-host interactions of LAB, the role of both virulent and temperate phages on the microbial composition, and the current knowledge of phageomes of fermented foods.

Investigating the growth kinetics in sourdough microbial associations.

In this study we investigated the effect of the single strain in stabilization of type I sourdough microbial associations by crossing six different Fructilactobacillus sanfranciscensis with five Kazachstania humilis strains. Furthermore, we compared three predictive models, Zwitwering based on Gompertz's equation, Baranyi and Roberts' function and Schiraldi's function to evaluate which one best fitted the experimental data in determining the behaviour of co-cultivated microorganisms. Specific growth rates (µm) and lag time (λ) values for each mixed population were assessed. Results showed that the different F. sanfranciscensis strains significantly steer the growth kinetics within the pair and affect the ratio bacterial/yeast cells, as data analysis confirmed, whereas K. humilis accommodates to the bacterial strain. To compare the growth models, Root Mean Square (RMS) values were calculated for each predicted curve by implementing an algorithm based on an iterative process to minimize the deviation among observed and calculated data. Schiraldi's function performed better than the others, revealing, on average, the smallest RMS values and providing the best fitting for over 70% of co-cultivation experiments. Models prove to be consistent in predicting growth kinetics of microbial consortia too.

Lactic Acid Bacteria Adjunct Cultures Exert a Mitigation Effect against Spoilage Microbiota in Fresh Cheese.

Lactic acid bacteria (LAB) have a strong mitigation potential as adjunct cultures to inhibit undesirable bacteria in fermented foods. In fresh cheese with low salt concentration, spoilage and pathogenic bacteria can affect the shelf life with smear on the surface and packaging blowing. In this work, we studied the spoilage microbiota of an Italian fresh cheese to find tailor-made protective cultures for its shelf life improvement. On 14-tested LAB, three of them, namely Lacticaseibacillus rhamnosus LRH05, Latilactobacillus sakei LSK04, and Carnobacterium maltaromaticum CNB06 were the most effective in inhibiting Gram-negative bacteria. These cultures were assessed by the cultivation-dependent and DNA metabarcoding approach using in vitro experiments and industrial trials. Soft cheese with and without adjunct cultures were prepared and stored at 8 and 14 °C until the end of the shelf life in modified atmosphere packaging. Data demonstrated that the use of adjunct cultures reduce and/or modulate the growth of spoilage microbiota at both temperatures. Particularly, during industrial experiments, C. maltaromaticum CNB06 and Lcb. rhamnosus RH05 lowered psychrotrophic bacteria of almost 3 Log CFU/g in a 5-week stored cheese. On the contrary, Llb. sakei LSK04 was able to colonize the cheese but it was not a good candidate for its inhibition capacity. The combined approach applied in this work allowed to evaluate the protective potential of LAB strains against Gram-negative communities.

Potencia y actividad electromiográfica en voleibolistas universitarios / Power and electromyographic activity in college volleyball players

Resumen El propósito del estudio fue determinar la potencia relativa del miembro inferior y actividad electromiográfica de superficie (EMGs) del glúteo mayor (GM), vasto medial (VM), vasto lateral (VL) y gastrocnemio lateral (GASLAT), durante un salto contramovimiento (CMJ) y un salto Abalakov (ABK). Un total de 24 voleibolistas universitarios se dividieron en dos grupos iguales asignados por el nivel de competencia: el grupo 1 (G1), compuesto por voleibolistas de 1ª división universitaria y el grupo 2 (G2), compuesto por voleibolistas de 2ª división universitaria. Cada uno fue sometido a dos evaluaciones simultáneas de potencia y EMGs. Para la potencia se utilizó un sistema de grabación en 2D, por medio de un seguimiento del trocánter mayor con una cámara de 250 fps. Esta grabación se sometió a una medición por medio de software (Tracker), para obtener los valores de potencia absoluta. La EMGs se realizó por medio de un electromiógrafo Delsys Trigno en los músculos GM, VM, VL y GASLAT. Se presentaron diferencias significativas en %PeakRMS del VL (G1=65.210.2; G2=54.0±11.7 %PeakRMS; p0.05) y ABK (p>0.05). G.=50.6±7.2 %PeakRMS; p0.05) y ABK (p>0.05).

Abstract The purpose of this study was to determine the relative power of lower limbs and the surface electromyographic activity (EMG) of the gluteus maximus (GM), vastus medialis (VM), vastus lateralis (VL), and lateral gastrocnemius (GASLAT) during a countermovement jump (CMJ) and an Abalakov jump (ABK). Twenty-four college volleyball players were divided into two equal groups assigned by division: Group 1 (G1), comprised of volleyball players from the 1st university division, and Group 2 (G2), comprised of volleyball players from the 2nd university division. Both groups took two simultaneous EMG and power assessments. For the power assessment, a 2D recording system was used to track the greater trochanter with a 250fps camera. The video was analyzed with the Tracker 4.96 software to obtain absolute power values. The EMG activity was measured using a Delsys Trigno® electromyograph in the GM, VM, VL, and GASLAT muscles. Significant differences were found in %PeakRMS of VL (G1=65.210.2; G2=54.0±11.7 %PeakRMS; p 0.05) and ABK (p>0.05).

Resumo Este estudo teve como objetivo determinar a potência relativa do membro inferior e atividade eletromiográfica (EMG) de superfície do glúteo máximo (GM), vasto medial (VM), vasto lateral (VL) e gastrocnêmio lateral (GASLAT) durante um salto contramovimento (CMJ) e um salto Abalakov (ABK). No total foram 24 jogadores de vôlei universitários divididos em dois grupos iguais, determinados pelo nível de competição: o grupo 1 (G1), composto por jogadores de 1ª divisão universitária e o grupo 2 (G2), composto por jogadores de vôlei de 2ª divisão universitária. Cada um foi submetido a duas avaliações simultâneas de potência e EMG de superfície. Para a potência foi utilizada um sistema de gravação 2D, por meio de um segmento do trocânter maior com uma câmara de 250 Fps. Essa gravação foi submetida a uma medição por meio de software (Tracker), para obter os valores de potência absoluta. A EMG de superfície foi realizada por meio do aparelho de eletromiografia Delsys Trigno nos músculos GM, VM, VL e GASLAT. Houve diferenças significativas em %PeakRMS do VL (G1=65,210,2; G2=54,0±11,7 %PeakRMS; p0,05) e ABK (p>0,05).

10 Years on Time-Motion and Motor Actions of Paired Mixed Martial Arts Athletes.

This study verified the performance probabilities by mixed martial arts rounds by the same athletes, doing paired comparisons of time-motion and actions before and after 10 y. The sample was composed of 845 Ultimate Fighting Championship rounds of 45 athletes separated into before (M1, age range 34-44 y) and after (M2, age range 44-54 y). Motor-control (takedowns, submissions, chokes, locks, strike actions to the head, and body and leg strikes attempted and landed) and time-motion (high and low intensities and standing and ground times) analyses were done. The main results showed significant differences (P ≤ .05) in total strikes landed (M1 22 [13; 34] > M2 18 [10; 31.7]), total strikes attempted (M1 41 [24.5; 62] > M2 35 [21; 48]), single head strikes attempted (M1 19 [9; 34.5] > M2 16.5 [9; 28]), single body strikes landed (M1 1 [0; 4] > M2 1 [0; 2]), single body strikes attempted (M1 2 [0; 5] > M2 1 [0; 3]), takedowns attempted (M1 1 [0; 2] > M2 1 [0; 2]), standing combat time (M1 2:10.28 [1:38.95] > M2 1:55.56 [1:32.17]), and low-intensity time (M1 2:11.45 [1:38.95] > M2 1:56.26 [1:31.89]). Variables that increased the probability to be associated with over the years were body strikes landed, head strikes landed, total strikes landed, and single strikes attempted, whereas body strikes attempted, head strikes attempted, total strikes attempted, and submission attempted had a negative association with mixed martial arts years of experience. Therefore, M2 athletes should be focused on standing combat time combined with strikes-landed actions, targeting the head-it has the highest potential performance probability and avoid unsuccessful body-strike attempts and submissions-which has the lowest potential performance probability over 10 years.

A 12-Year Cohort Study of Doc-Stoppage in Professional Mixed Martial Arts.

Purposes: To determine actions during bouts that generate serious enough injury to stop the bout; verifying the injury incidence, types, and prevalence of doctor stoppages (doc-stoppage); and identify potential risk factors by analyzing technical-tactical profiles for injury in sanctioned mixed martial arts bouts taking place over a 12-y period. Methods: This research analyzed 440 paired mixed martial arts matches separated by doc-stoppage (n = 220) and no doc-stoppage (n = 220) from 2002 to 2014. Technical knockouts for doc-stoppage were diagnosed and managed by attending ringside doctors, and the time-motion variables were categorized into total combat time separated by low- or high-intensity activities per round, stand-up, or groundwork actions, P ≤ .05. Results: The main cause of injuries in doc-stoppage situations was due to facial injuries (>90%), with 87.1% occurring after striking actions during the second round. Lacerations were the leading type of injury, which occurred with 80% frequency. The results showed differences between doc-stoppage and no doc-stoppage for standing combat with low-intensity actions (130.6 [8.5] s vs 83.3 [6.9] s for first round; 115.7 [10.5] s vs 100.1 [9.6] s for second round, and 121.5 [19.5] s vs 106.3 [11.7] s for third round) and total strike attempts (34.5, 23.0-51.8 vs 25.0, 12.0-40.8); in standing combat, head strike attempts (21, 10-33 vs 11, 4-21) and body strikes (2.5, 1.0-5.8 vs 1.0-2), and in groundwork combat, head strikes landed (0.0-3.0 vs 0.0-5.0). Conclusions: This research showed higher values of strike attempts with 2 main orientations, namely the head (on the ground and in stand-up actions) and body (in stand-up actions), and may provide important information regarding the technical knockout and when it can be called by officials supervising mixed martial arts bouts.

Selected Probiotic Lactobacilli Have the Capacity To Hydrolyze Gluten Peptides during Simulated Gastrointestinal Digestion.

The aim of this study was to demonstrate the capacity of probiotic lactobacilli to hydrolyze immunogenic gluten peptides. Eighteen commercial strains of probiotic lactobacilli with highly variable peptidase activity (i.e., aminopeptidase N, iminopeptidase, prolyl endopeptidyl peptidase, tripeptidase, prolidase, prolinase, and dipeptidase), including toward Pro-rich peptides, were tested in this study. Ten probiotic strains were selected on the basis of their specific enzyme activity. When pooled, these 10 strains provided the peptidase portfolio that is required to completely degrade the immunogenic gluten peptides involved in celiac disease (CD). The selected probiotic mixture was able to completely hydrolyze well-known immunogenic epitopes, including the gliadin 33-mer peptide, the peptide spanning residues 57 to 68 of the α9-gliadin (α9-gliadin peptide 57-68), A-gliadin peptide 62-75, and γ-gliadin peptide 62-75. During digestion under simulated gastrointestinal conditions, the pool of 10 selected probiotic lactobacilli strongly hydrolyzed the wheat bread gluten (ca. 18,000 ppm) to less than 10 ppm after 360 min of treatment. As determined by multidimensional chromatography (MDLC) coupled to nanoelectrospray ionization (nano-ESI)-tandem mass spectrometry (MS/MS), no known immunogenic peptides were detected in wheat bread that was digested in the presence of the probiotics. Accordingly, the level of cytokines (interleukin 2 [IL-2], IL-10, and interferon gamma [IFN-γ]) produced by duodenal biopsy specimens from CD patients who consumed wheat bread digested by probiotics was similar to the baseline value (negative control). Probiotics that specifically hydrolyze gluten polypeptides could also be used to hydrolyze immunogenic peptides that contaminate gluten-free products. This could provide a new and safe adjunctive therapy alternative to the gluten-free diet (GFD).IMPORTANCE This study confirmed that probiotic Lactobacillus strains have different enzymatic abilities for hydrolyzing polypeptides, including the Pro-rich epitopes involved in the pathology of CD. Ten lactobacilli with complementary peptidase activities that hydrolyze gluten peptides during simulated gastrointestinal digestion were selected and tested. The results collected showed the potential of probiotic formulas as novel dietary treatments for CD patients.

Genomic Characterization of Dairy Associated Leuconostoc Species and Diversity of Leuconostocs in Undefined Mixed Mesophilic Starter Cultures.

Undefined mesophilic mixed (DL-type) starter cultures are composed of predominantly Lactococcus lactis subspecies and 1-10% Leuconostoc spp. The composition of the Leuconostoc population in the starter culture ultimately affects the characteristics and the quality of the final product. The scientific basis for the taxonomy of dairy relevant leuconostocs can be traced back 50 years, and no documentation on the genomic diversity of leuconostocs in starter cultures exists. We present data on the Leuconostoc population in five DL-type starter cultures commonly used by the dairy industry. The analyses were performed using traditional cultivation methods, and further augmented by next-generation DNA sequencing methods. Bacterial counts for starter cultures cultivated on two different media, MRS and MPCA, revealed large differences in the relative abundance of leuconostocs. Most of the leuconostocs in two of the starter cultures were unable to grow on MRS, emphasizing the limitations of culture-based methods and the importance of careful media selection or use of culture independent methods. Pan-genomic analysis of 59 Leuconostoc genomes enabled differentiation into twelve robust lineages. The genomic analyses show that the dairy-associated leuconostocs are highly adapted to their environment, characterized by the acquisition of genotype traits, such as the ability to metabolize citrate. In particular, Leuconostoc mesenteroides subsp. cremoris display telltale signs of a degenerative evolution, likely resulting from a long period of growth in milk in association with lactococci. Great differences in the metabolic potential between Leuconostoc species and subspecies were revealed. Using targeted amplicon sequencing, the composition of the Leuconostoc population in the five commercial starter cultures was shown to be significantly different. Three of the cultures were dominated by Ln. mesenteroides subspecies cremoris. Leuconostoc pseudomesenteroides dominated in two of the cultures while Leuconostoc lactis, reported to be a major constituent in fermented dairy products, was only present in low amounts in one of the cultures. This is the first in-depth study of Leuconostoc genomics and diversity in dairy starter cultures. The results and the techniques presented may be of great value for the dairy industry.

The Baseplate of Lactobacillus delbrueckii Bacteriophage Ld17 Harbors a Glycerophosphodiesterase.

Glycerophosphodiester phosphodiesterases (GDPDs; EC 3.1.4.46) typically hydrolyze glycerophosphodiesters to sn-glycerol 3-phosphate (Gro3P) and their corresponding alcohol during patho/physiological processes in bacteria and eukaryotes. GDPD(-like) domains were identified in the structural particle of bacterial viruses (bacteriophages) specifically infecting Gram-positive bacteria. The GDPD of phage 17 (Ld17; GDPDLd17), representative of the group b Lactobacillus delbrueckii subsp. bulgaricus (Ldb)-infecting bacteriophages, was shown to hydrolyze, besides the simple glycerophosphodiester, two complex surface-associated carbohydrates of the Ldb17 cell envelope: the Gro3P decoration of the major surface polysaccharide d-galactan and the oligo(glycerol phosphate) backbone of the partially glycosylated cell wall teichoic acid, a minor Ldb17 cell envelope component. Degradation of cell wall teichoic acid occurs according to an exolytic mechanism, and Gro3P substitution is presumed to be inhibitory for GDPDLd17 activity. The presence of the GDPDLd17 homotrimer in the viral baseplate structure involved in phage-host interaction together with the dependence of native GDPD activity, adsorption, and efficiency of plating of Ca(2+) ions supports a role for GDPDLd17 activity during phage adsorption and/or phage genome injection. In contrast to GDPDLd17, we could not identify any enzymatic activity for the GDPD-like domain in the neck passage structure of phage 340, a 936-type Lactococcus lactis subsp. lactis bacteriophage.

Novel phage group infecting Lactobacillus delbrueckii subsp. lactis, as revealed by genomic and proteomic analysis of bacteriophage Ldl1.

Ldl1 is a virulent phage infecting the dairy starter Lactobacillus delbrueckii subsp. lactis LdlS. Electron microscopy analysis revealed that this phage exhibits a large head and a long tail and bears little resemblance to other characterized phages infecting Lactobacillus delbrueckii. In vitro propagation of this phage revealed a latent period of 30 to 40 min and a burst size of 59.9 +/- 1.9 phage particles. Comparative genomic and proteomic analyses showed remarkable similarity between the genome of Ldl1 and that of Lactobacillus plantarum phage ATCC 8014-B2. The genomic and proteomic characteristics of Ldl1 demonstrate that this phage does not belong to any of the four previously recognized L. delbrueckii phage groups, necessitating the creation of a new group, called group e, thus adding to the knowledge on the diversity of phages targeting strains of this industrially important lactic acid bacterial species.

Molecular characterization of three Lactobacillus delbrueckii subsp. bulgaricus phages.

In this study, three phages infecting Lactobacillus delbrueckii subsp. bulgaricus, named Ld3, Ld17, and Ld25A, were isolated from whey samples obtained from various industrial fermentations. These phages were further characterized in a multifaceted approach: (i) biological and physical characterization through host range analysis and electron microscopy; (ii) genetic assessment through genome analysis; (iii) mass spectrometry analysis of the structural components of the phages; and (iv), for one phage, transcriptional analysis by Northern hybridization, reverse transcription-PCR, and primer extension. The three obtained phage genomes display high levels of sequence identity to each other and to genomes of the so-called group b L. delbrueckii phages c5, LL-Ku, and phiLdb, where some of the observed differences are believed to be responsible for host range variations.

Candida milleri species reveals intraspecific genetic and metabolic polymorphisms.

Candida milleri, together with Candida humilis, is the most representative yeast species found in type I sourdough ecosystems. In this work, comparison of the ITS region and the D1/D2 domain of 26S rDNA gene partial sequences, karyotyping, mtDNA-RFLP analysis, Intron Splice Site dispersion (ISS-PCR) and (GTG)5 microsatellite analyses, assimilation test of different carbohydrates, and metabolome assessment by FT-IR analysis, were investigated in seventeen strains isolated from four different companies as well as in type strains CBS6897(T) and CBS5658(T). Most isolates were ascribed to C. milleri, even if a strong relatedness was confirmed with C. humilis as well, particularly for three strains. Genetic characterization showed a high degree of intraspecific polymorphism since 12 different genotypes were discriminated. The number of chromosomes varied from 9 to 13 and their size ranged from less than 0.3 to over 2 Mbp. Phenotypic traits let to recognize 9 different profiles of carbon sources assimilation. FT-IR spectra from yeast cells cultivated in different media and collected at different growth phases revealed a diversity of behaviour among strains in accordance with the results of PCR-based fingerprinting. A clear evidence of the polymorphic status of C. milleri species is provided thus representing an important feature for the development of technological applications in bakery industries.

Bacteriophage-insensitive mutants for high quality Crescenza manufacture.

Streptococcus thermophilus is a thermophilic lactic acid bacterium used as starter culture for the manufacture of fermented dairy products. For the production of Crescenza and other soft cheeses, Sacco has developed and provides dairies with three different defined blends of S. thermophilus strains. Each blend contains two different S. thermophilus strains. The strains were selected based on their unique technological properties as well as different phage profiles. Analysis of 133 whey samples collected in 2009-2010 from Italian dairies showed a high prevalence (about 50%) of bacteriophage attacks on the blend ST020. More specifically, the strain S. thermophilus ST1A was found to be the preferred target of the bacteriophages. A bacteriophage insensitive mutant (BIM5) of the phage-sensitive strain ST1A was successfully developed and used to substitute strain ST1A in the Crescenza starter culture ST020. The strain BIM5 showed identical technological and industrial traits as those of the phage-sensitive strain ST1A. The improved resistance of the modified Crescenza starter culture ST020R was confirmed at Italian dairies, and its effectiveness monitored on 122 whey samples collected in 2011-2012. Compared to the previous values (2009-2010), the use of the phage-hardened blend ST020R allowed reducing of frequency of phage attacks from about 50 to less than 5% of the whey samples investigated.

The effects of liquid versus spray-dried Laminaria digitata extract on selected bacterial groups in the piglet gastrointestinal tract (GIT) microbiota.

In this study, the effects of supplementing animal feed with a liquid and spray-dried fucoidan and laminarin extract, derived from the seaweed Laminaria digitata on the porcine gastrointestinal microbiota, specifically the communities of Lactobacillus, Bifidobacterium and enterobacteria were evaluated. Twenty four piglets were fed one of three diets over a 21-day period to determine the effect that each had on the bacterial communities. The dietary treatments were as follows; (1) control diet, (2) control diet plus spray-dried formulation of laminarin fucoidan (L/F-SD) extract, (3) control diet plus a liquid formulation of (L/F-WS) extract. Control diet consisted of wheat, soya bean meal, soya oil and a vitamin and mineral mixture. The L/F-SD and L/F-WS supplemented diets had equal proportion of 500 ppm laminarin and fucoidan. At the end of the 21 day feeding period all animals were sacrificed and samples were collected from the ileum, caecum and colon. Counts were determined for Lactobacillus, Bifidobacterium and enterobacteria. Plate count analysis revealed that the L/F-SD diet caused a statistically significant 1.5 log and 2 log increases in the Lactobacillus and Bifidobacterium counts of ileum samples respectively. A greater difference was observed with the L/F-WS diet in that Lactobacillus and Bifidobacterium increased by 2 log and 3 log respectively. Alterations in the Lactobacillus species composition of the gastrointestinal tract (GIT) were analysed using specific PCR - denaturing gradient gel electrophoresis (PCR-DGGE). The DGGE profiles indicated that Lactobacillus species richness decreased along the gastrointestinal tract i.e. the number of dominant species detected in the colon was less than those detected in the ileum and caecum irrespective of the diet consumed. Consumption of both the L/F-SD and L/F-WS diets resulted in a richer Lactobacillus species composition in the ileum, with the L/F-SD diet being associated the emergence of Lactobacillus agilis in the colon. The study indicated that the L/F-WS extract was superior to the L/F-SD extract in increasing the titre of beneficial bacteria in the gastrointestinal tract (GIT).

Increasing the heme-dependent respiratory efficiency of Lactococcus lactis by inhibition of lactate dehydrogenase.

The discovery of heme-induced respiration in Lactococcus lactis has radically improved the industrial processes used for the biomass production of this species. Here, we show that inhibition of the lactate dehydrogenase activity of L. lactis during growth under respiration-permissive conditions can stimulate aerobic respiration, thereby increasing not only growth efficiency but also the robustness of this organism.

Exploration of the genomic diversity and core genome of the Bifidobacterium adolescentis phylogenetic group by means of a polyphasic approach.

In the current work, we describe genome diversity and core genome sequences among representatives of three bifidobacterial species, i.e., Bifidobacterium adolescentis, Bifidobacterium catenulatum, and Bifidobacterium pseudocatenulatum, by employing a polyphasic approach involving analysis of 16S rRNA gene and 16S-23S internal transcribed spacer (ITS) sequences, pulsed-field gel electrophoresis (PFGE), and comparative genomic hybridization (CGH) assays.

Influence of in-situ synthesized exopolysaccharides on the quality of gluten-free sorghum sourdough bread.

The majority of gluten-free breads on the market are of poor sensory and textural quality. Exopolysaccharides (EPS) formed from sucrose during sourdough fermentation can improve the technological properties of gluten-free breads and potentially replace hydrocolloids. In this study, the influence of in situ formed EPS on dough rheology and quality of gluten-free sorghum bread was investigated. Dextran forming Weissella cibaria MG1 was compared to reuteran producing Lactobacillus reuteri VIP and fructan forming L. reuteri Y2. EPS containing bread batters were prepared by adding 10% and 20% of sourdough. As control served batters and bread containing sourdoughs fermented without sucrose and batters and bread without sourdough addition. The amount of EPS formed in situ ranged from 0.6 to 8.0 g/kg sourdough. EPS formed during sourdough fermentation were responsible for the significant decrease in dough strength and elasticity, with in situ formed dextran exhibiting the strongest impact. Increased release of glucose and fructose from sucrose during fermentation enhanced CO2 production of yeast. Organic acids in control sourdough breads induced hardening of the bread crumb. EPS formed during sourdough fermentation masked the effect of the organic acids and led to a softer crumb in the fresh and stored sorghum bread. Among EPS, dextran showed the best shelf life improvements. In addition to EPS, all three strains produced oligosaccharides during sorghum sourdough fermentation contributing to the nutritional benefits of gluten-free sorghum bread. Results of this study demonstrated that EPS formed during sourdough fermentation can be successfully applied in gluten-free sorghum flours to improve their bread-making potentials.