Use of dairy and non-dairy Lactobacillus plantarum, Lactobacillus paraplantarum and Lactobacillus pentosus strains as adjuncts in cheddar cheese

Lactobacilli have been used as adjunct cultures in the manufacture of different cheeses with the objective of accelerating ripening and/or improving cheese quality, but no studies have been conducted with strains from non-dairy origins. A miniature cheddar-type cheese model was used to screen ten dairy and non-dairy Lactobacillus plantarum, Lactobacillus paraplantarum and Lactobacillus pentosus strains for their performances as adjuncts in cheese manufacture. All strains were able to grow and survive in the cheese environment and produced only minor, although statistically significant, changes in gross cheese composition. Adjuncts affected secondary proteolysis causing differences in the levels of free amino groups, total free amino acids and reversed-phase HPLC (RP-HPLC) profiles of pH 4.6-soluble extract. Three strains were selected on the basis of differences in proteolysis pattern and used in a pilot-plant production of cheddar cheese, which was ripened for 180 days. The results confirmed that use of L. plantarum adjuncts significantly affected secondary proteolysis as measured by free amino acid production with minor impact on gross composition and primary starter performance, but the impact on RP- HPLC profiles of pH 4.6-soluble extracts was not statistically significant. The use of a strain originally isolated from olive brine fermentation, L. plantarum P1.5, resulted in significantly improved preference scores over the control

A study on relationships between durum wheat semolina properties, technological mixing parameters and the properties of dough after mixing

Partial least square regression analysis was used to study the correlation between X variables (semolina quality, hydration level and mixing time) and Y variables, which were, in a first model, dough consistency during mixing, and, in a second model, dough properties after mixing (strength, elasticity, density) and leavening (maximum volume). The first model showed a predictive residual sum of squares (PRESS) of 2.98 and a predictive R2 (Q2) of 0.92, and highlighted the key role of hydration and mixing time ondough consistency. The second model had the best PRESS (8.25) and Q2 (0.94) values for dough volume and indicated that the volume increased with increasing mixing time until the dough consistency decreased of 20–30%. Dough volume was primarily affected by hydration. The model indicated that maximum volume after leavening, corresponding to optimum mixing time, was obtained with a soft and elastic dough, with a low-density valu

Temperature and respiration affect the growth and stress resistance of Lactobacillus plantarum C17

Aims: The aim of the study is to gain further insight on the respiratory behaviour of Lactobacillus plantarum and its consequences on stress tolerance. Methods and Results: We investigated the effect of temperature and respiration on the growth and stress (heat, oxidative, freezing, freeze-drying) response of Lact. plantarum C17 during batch cultivations. Temperature as well as respiration clearly affected the physiological state of cells, and generally, cultures grown under respiratory conditions exhibited improved tolerance of some stresses (heat, oxidative, freezing) compared to those obtained in anaerobiosis. Our results revealed that the activities in cell-free extracts of the main enzymes related to aerobic metabolism, POX (pyruvate oxidase) and NPR (NADH peroxidase), were significantly affected by temperature. POX was completely inhibited at 37°C, while the activity of NPR slightly increased at 25°C, indicating that in Lact. plantarum, the temperature of growth may be involved in the activation and modulation of aerobic/respiratory metabolism. Conclusions: We confirmed that respiration confers robustness to Lact. plantarum cells, allowing a greater stress tolerance and advantages in the production of starter and probiotic cultures. Significance and Impact of the Study: This is the first study on respiratory metabolism on a strain other than the model strains WCFS1; novel information on the role of temperature in the modulation of aerobic/ respiratory metabolism in Lact. plantarum is presented

Effect of Respiratory Growth on the Metabolite Production and Stress Robustness of Lactobacillus casei N87 Cultivated in Cheese Whey Permeate Medium

Cheese whey permeate (WP) is a low-cost feedstock used for the production of biomass and metabolites from several lactic acid bacteria (LAB) strains. In this study, Lactobacillus casei N87 was cultivated in an optimized WP medium (WPM) to evaluate the effect of anaerobic and respiratory conditions on the growth performances (kinetics, biomass yield), consumption of sugars (lactose, galactose, glucose) and citrate, metabolite production [organic acids, volatile organic compounds (VOCs)] and stress survival (oxidative, heat, freezing, freeze-drying). The transcription of genes involved in the main pathways for pyruvate conversion was quantified through Real Time-PCR to elucidate the metabolic shifts due to respiratory state. Cultivation in WPM induced a diauxic growth in both anaerobic and respiratory conditions, and L. casei N87 effectively consumed the lactose and galactose present in WPM. Genomic information suggested that membrane PTS system and tagatose-6-P pathway mediated the metabolism of lactose and galactose in L. casei N87. Respiration did not affect specific growth rate and biomass production, but significantly altered the pyruvate conversion pathways, reducing lactate accumulation and promoting the formation of acetate, acetoin and diacetyl to ensure the redox balance. Ethanol was not produced under either cultivation. Pyruvate oxidase (pox), acetate kinase (ack), alpha-acetolactate decarboxylase (ald), acetolactate synthase (als) and oxaloacetate decarboxylase (oad) genes were up-regulated under respiration, while L-lactate dehydrogenase (ldh), pyruvate formate lyase (pfl), pyruvate carboxylase (pyc), and phosphate acetyltransferase (pta) were down regulated by oxygen. Transcription analysis was consistent with metabolite production, confirming that POX-ACK and ALS-ALD were the alternative pathways activated under aerobic cultivation. Respiratory growth affected the production of volatile compounds useful for the development of aroma profile in several fermented foods, and promoted the survival of L. casei N87 to oxidative stresses and long-term storage. This study confirmed that the respiration-based technology coupled with cultivation on low-cost medium may be effectively exploited to produce competitive and functional starter and/or adjunct cultures. Our results, additionally, provided further information on the activation and regulation of metabolic pathways in homofermentative LAB grown under respiratory promoting conditions

Growth and bacteriocin production by Enterococcus faecium DPC1146 in batch and continuous culture

Production of the bacteriocin enterocin 1146 (E1146) by Enterococcus faecium DPC1146 was studied in batch and continuous fermentation. Growth was strongly inhibited by lactic acid. In batch fermentations maximum E1146 activity (2.8 MBU L-1) was obtained in 9 h with 20 g L-1 glucose. Increase in initial glucose concentration did not lead to a proportional increase in E1146 activity. A simple linear model was found to be adequate to explain the relationship between specific bacteriocin production rate and specific growth rate in batch fermentations with initial glucose concentration higher than 20 g L-1. Maximum bacteriocin activity (2.9-3.2 MBU L-1) was obtained in continuous fermentations at dilution rates between 0.12 and 0.17 h-1 and specific bacteriocin production rate increased linearly with dilution rate

Evaluation of a differential medium for the preliminary identification of members of the Lactobacillus plantarum and Lactobacillus casei groups

A medium originally developed for differential enumeration of probiotic species in fermented milk (mMRS-BPB, Lee and Lee 2008) was evaluated for its ability to correctly discriminate members of the Lactobacillus plantarum (L. plantarum) and L. casei groups from other species. The medium was tested on 461 strains of lactic acid bacteria (LAB) belonging to eight genera and thirty-five species. Colony morphology was relatively consistent for L. plantarum, L. paraplantarum, L. pentosus, L. paracasei, L. casei, and L. rhamnosus, but, when used alone, was not always sufficient to discriminate these species from other species potentially present in cheese. A procedure based on tree classification was developed to obtain preliminary identification on the basis of colony morphology, cell morphology, and CO2 production from glucose. By combining results of the tree classification procedure and heuristic rules, correct preliminary identification at the species or group level could be obtained in 74.4 % of cases overall, and the percentage of correct identifications was as high as 88-100 % for members of the L. plantarum and L. casei groups. When species belonging to groups that can be easily discriminated by rapid molecular methods were combined, the decision tree allowed to correct identification at the group level for the 95 % of the strains. Logistic regression was used to evaluate the effect of strain, operator, light source, and incubation temperature. Although all factors significantly affected one or more of the characters used for identification, the classification procedure proved to be quite robust. It may be difficult to use mMRS-BPB in the differential enumeration of LAB in cheese, except when species composition is relatively simple; however, it can be used as a simple tool to guide molecular identification in studies focused on the isolation of new strains from cheese

Gestño de dunas costeiras e conflitos de usos nos estados do Ceará e Rio Grande do Norte- Nordeste do Brasil

O objetivo deste trabalho foi discutir os critérios de classificaçào e enquadramento dos tipos de uso e ocupaçào nas dunas costeiras nos estados do Ceará e Rio Grande do Norte. Os mais diversos tipos de dunas foram compartimentados com ênfase na sua gênese, dinámica e peculiaridades, revelando as fragilidades ambientais, a partir do cruzamento das principais formas de uso e ocupaçào, Os aspectos dinámicos e jurídicos na classificaçào de dunas costeiras também foram discutidos. As zonas de preservaçào e conservaçào, com suas respectivas fragilidades e magnitude de impacto, nortearam a indicaçàc dos usos tolerados e proibidos, com as devidas adaptaçòes a realidade socioeconêmica e tradiçòes culturais dessas áreas.The goal of this paper is the discussion about classification criteria and setting for use type and occupation for Cearà and Rio Grande do Norte coastal dunes. The great diversity of dunes was divided from genetical, dynamics and other specificities showing the environmental fragilities from their use and occupation forms. Dynamical and juridical aspects to classify coastal dunes are discussed. Preservation zones with their own fragilities and impact amount could indicate allowed and not allowed uses with adaptation to the socioeconomic, cultural and traditional contexts

Functional properties of Lactobacillus plantarum strains: A multivariate screening study

Abstract Thirty-two Lactobacillus plantarum strains isolated from different sources were genetically characterized at subspecies level with recA gene based multiplex PCR and pulsed-field electrophoresis. All the strains were tested in vitro for functional properties (ability to form biofilms, agglutination of yeast cells, bile salt hydrolase activity, β-galactosidase activity, surface hydrophobicity, resistance to lysozyme, gastric juice and bile salts), for antimicrobial activity and for antibiotic resistance. The presence of bsh and msa genes and of the pln bacteriocin loci were also evaluated. Hierarchical cluster analysis was used to identify eight different plantaritypes sharing similar patterns of pln loci. A global functional score was calculated by transforming values for continuous in vitro functional properties in an ordinal scale by cluster analysis, while a nominal scale was used for the other properties. Multidimensional scaling was used to evaluate the similarity in functional properties among the isolates and to evaluate the relationships between source of isolation and functional properties. Nine strains showed the best in vitro functional potential and a significant relationship was found between source of isolation and functional score. This study confirmed a high heterogeneity in functional properties among L. plantarum strains and provides insight for optimal screening strategies

Polymorphisms in stress response genes in Lactobacillus plantarum: implications for classification and heat stress response

The polymorphism of 5 stress response genes (hrcA, ctsR, clpP, ftsH, dnaK) in 32 Lactobacillus plantarum strains was evaluated by multilocus restriction typing (MLRT) and by sequence analysis of ctsR, hrcA and clpP genes. Both these approaches allowed the discrimination of the subspecies L. plantarum ssp. plantarum and L. plantarum ssp. argentoratensis. HrcA sequence analysis also allowed discrimination at the species and subspecies level of several species of lactic acid bacteria, thus confirming that it can be used as a valuable taxonomic marker. No significant relationship was found between stress response gene polymorphism and resistance to heat treatments. The effect of temperature on growth kinetics and the protein expression were investigated for selected strains carrying different mutations in hrcA. L. plantarum ssp. argentoratensis NCIMB12120 and L. plantarum ssp. plantarum DPC2159, both of which had mutations in domains of HrcA which are important for the repressor functionality, had a reduced growth rate at all temperatures tested (25, 30, 37, 40, and 42 °C) compared to L. plantarum WCFS1. In L. plantarum DPC2159, protein expression upon temperature shifts from 25 to 40 °C or growth at 40 °C was altered compared to L. plantarum WCFS1, but further study is needed to unequivocally confirm the relationship with mutations in hrcA