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Food science technology, Sciences technologies alimentaires, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Industries agroalimentaires, Food industries, Industries laitières et fromagères. Crèmes glacées, Milk and cheese industries. Ice creams, Microbiologie alimentaire, Food microbiology, Bactérie, Bacteria, Lactobacillaceae, Protéine lait, Milk protein, Proteína leche, Bactériocine, Bacteriocin, Bacteriocina, Caséine, Casein, Caseina, Interaction microorganisme, Microorganism interrelationships, Interacción microorganismo, Lactobacillus curvatus, Listeria monocytogenes, Peptide, Peptides, Péptido, Production, Producción, Purification, Purificación, and Casein-derived bioprotective peptides

Three novel bioactive peptides (BAP1-3) from Lactobacillus curvatus CWBI-B28 were isolated and purified using de Man, Rogosa and Sharp (MRS) broth by a three-step protein purification protocol including ammonium sulfate precipitation, hydrophobic C18 Sep-Pak column and reverse-phase high performance liquid chromatography (RP-HPLC). This procedure allowed the recovery of chromatographically pure antimicrobial peptides with the yields of 19%, 10% and 15% of BAP1, BAP2 and BAP3, respectively. The respective apparent molecular masses as determined by tricine-SDS-polyacrilamide gel electrophoresis were 6365, 3426 and 3496. N-terminal amino acid sequencing of the BAPs and comparison of their sequences with those of international data bases indicated that BAP1 is more likely to be a casein-derived bioactive protein produced upon hydrolysis of the tryptone present in MRS broth by Lb. curvatus CWBI-B28 during active growth. However, the identity of BAP2 and BAP3 could not be determined with certainty ; yet, they would be novel bacteriocins not fitting in any of the known classes of bacteriocins. Therefore, this strain would have the ability to produce intrinsic antimicrobial substances and also release bioprotective peptides from milk-proteins upon cultivation in milk or casein-containing food products due to its proteolytic activity. Thus, Lb. curratus CWBI-B28 possesses a good potential to be used in food preservation and safety.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Biotechnology, Biotechnologies, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biotechnologie, Biotechnology, Fungi Imperfecti, Fungi, Huile ricin, Castor oil, Aceite ricino, Lactone, Lactona, Levure, Yeast, Levadura, Mésophilie, Mesophily, Mesofilia, Production, Producción, Psychrophilie, Psychrophily, Psicrofilia, Rhodotorula aurantiaca, Mesophilic, Psychrophilic, and γ-Decalactone

Among 18 psychrophilic strains isolated near the Antarctic Station, the psychrophilic strain Rhodotorula aurantiaca A19 was selected for its ability of growth and γ-decalactone production at low temperatures. The effects of temperature, initial pH, and castor oil concentration on the growth and γ-decalactone production by a psychrophilic and a mesophilic strain of R. aurantiaca were investigated. The highest γ-decalactone production in flasks (5.8 g/l) was obtained with the strain A19 at 14 °C and initial pH 7.0 in medium containing 20 g/l castor oil. On the other hand, these factors did not affect the production of γ-decalactone by the mesophilic strain. In fennentor, a γ-decalactone concentration of 6.6 g/l was reached with the strain A19, whereas a maximum of 0.1 g/l was obtained with the mesophilic strain. Our results suggest that the ability to synthesize γ-decalactone is a particularity of the strain A19, since the mesophilic strain (no. 30645) produced small amounts, and the other (no. 31354) did not exhibit this property. It is, to our knowledge, the first report of γ-decalactone production by R. aurantiaca and furthermore by a psychrophilic yeast strain. Moreover, the amount of γ-decalactone obtained in fermentor with the strain 19 was on the order of concentrations usually described in patents.

Food science technology, Sciences technologies alimentaires, Animal sciences, zootechny, veterinary medicine, Sciences animales, zootechnie, médecine vétérinaire, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Industries agroalimentaires, Food industries, Industries de la viande et des produits carnés, Meat and meat product industries, Microbiologie alimentaire, Food microbiology, Bactériocine, Bacteriocin, Bacteriocina, Dégradation, Degradation, Degradación, Interaction microorganisme, Microorganism interrelationships, Interacción microorganismo, Produit carné, Meat product, Producto de carne, Viande porc, Pork, Carne cerdo, Commercial pork meat, Lactobacillus curvatus, Listeria monocytogenes, and Proteases

This work focused on Listeria monocytogenes growth inhibition and growth rebound in raw and cooked pork meat inoculated with Lactobacillus curvatus strains. During storage of raw meat homogenates in the presence of the bacteriocin-producing strain Lactobacillus curvatus CWBI-B28wt, the Listeria monocytogenes cfu count was initially reduced to an undetectable level, but a growth rebound occurred after two weeks, coinciding with loss of 70% of the bacteriocin activity present at the end of week 2. The Listeria growth rebound was suppressed when proteolysis of bacteriocin was countered by the absence of proteases (bacteriocin addition to cooked meat) or the presence of 1% soy flour (added to provide competing substrates). Further experiments confirmed that bacteriocin is sensitive to the action of proteolytic enzymes isolated from both Lactobacillus curvatus CWBI-B28wt and the meat matrix. Bacteriocin proteolysis thus emerges as a cause of Listeria growth rebound.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, Biotechnology, Biotechnologies, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biotechnologie, Biotechnology, Méthodes. Procédés. Technologies, Methods. Procedures. Technologies, Techniques d'immobilisation, Immobilization techniques, Généralités, General aspects, Ascomycota, Carboxylic ester hydrolases, Enzyme, Enzima, Esterases, Fungi, Hydrolases, Activité enzymatique, Enzymatic activity, Actividad enzimática, Adsorption, Adsorción, Etude comparative, Comparative study, Estudio comparativo, Immobilisation, Immobilization, Inmovilización, Liaison covalente, Covalent bond, Enlace covalente, Rendement, Yield, Rendimiento, Technique, Técnica, Triacylglycerol lipase, Yarrowia lipolytica, Reusability, and Yarrowia lipolytica lipase, Enzymatic activity, Immobilization

The purpose of this study was to immobilize lipase from Yarrowia lipolytica using three methods including inclusion, adsorption, and covalent bond to study enzyme leaching, storage, and catalytic properties. Sodium alginate and chitosan were the polymers selected to immobilize lipase by inclusion. The beads of each polymer were dried by freeze drying and fluidization. The results show that chitosan was more adapted to the inclusion of lipase. Even though freeze dried, bead activity was low compared to that of fluidized beads. The freeze-drying process seems to produce suitable beads for storage at 4 and 20 °C. The immobilization by adsorption was carried out on both celite and silica gel. Maximum immobilization yield of 76% was obtained with celite followed by 43% in silica gel. The enzyme adsorbed on the two supports exhibited greater stability at a certain temperature (50 °C) and in no polar solvents (Isooctane, n-heptane, and n-hexane). In addition, the lipase immobilized by covalent bond retained residual activity equitable to 70%. It was demonstrated that the enzyme immobilized by covalent bond showed greater activity (80%) after 5 months of storage.

Agronomy, agriculture, phytopathology, Agronomie, agriculture, phytopathologie, Food science technology, Sciences technologies alimentaires, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Industries agroalimentaires, Food industries, Microbiologie alimentaire, Food microbiology, Bactérie, Bacteria, Lactobacillaceae, Alimentation, Feeding, Alimentación, Bactériocine, Bacteriocin, Bacteriocina, Croissance, Growth, Crecimiento, Fermentation, Fermentación, Interaction microorganisme, Microorganism interrelationships, Interacción microorganismo, Lactobacillus curvatus, Performance, Rendimiento, Production, Producción, Taux, Rate, Tasa, bacteriocin, batch, fed-batch, feeding rate, and fermentation

The dynamics of cell growth and bacteriocin production by Lactobacillus curvatus CWBI-B28 in modified De Man/Rogosa/Sharp (mMRS) broth with various concentrations of glucose and complex nitrogen source (CNS; peptone, yeast extract and meat extract) was investigated in flask fermentations and in a laboratory fermentor using batch and fed-batch cultivations. In fed-batch fermentation the rate of feeding of the reactor with the substrates was either maintained constant (0.12 L h-1) or varied exponentially as a function of time. The results showed that both cell growth and bacteriocin activity were influenced by changes in the concentrations of glucose and CNS. Optimal growth and bacteriocin activity were obtained in mMRS broth containing 40 g L-1 glucose and 40 g L-1 CNS (mMRS40/40). A bacteriocin titre of 4266 AU mL-1 and a cell count of 8.7 log colony-forming units (cfu) mL-1 were recorded when this medium was used for cultivation. In batch fermentation using the same medium, a higher cell count (9.5 log cfu mL-1) and twice as much bacteriocin as in flask fermentation were produced. The highest bacteriocin titre (8533 AU mL-1) was obtained with fed-batch fermentation at an exponentially varying rate of feeding. Bacteriocin activity and cell dry mass did not always correlate.

Food science technology, Sciences technologies alimentaires, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Industries agroalimentaires, Food industries, Industries laitières et fromagères. Crèmes glacées, Milk and cheese industries. Ice creams, Additif alimentaire, Food additive, Aditivo alimentario, Bactérie, Bacteria, Micrococcales, Streptococcaceae, Antibactérien, Antibacterial agent, Antibacteriano, Bactériocine, Bacteriocin, Bacteriocina, Conservateur, Preservative, Conservador, Fermentation lactique, Lactic fermentation, Fermentación láctica, Interaction microorganisme, Microorganism interrelationships, Interacción microorganismo, Lactococcus lactis subsp. lactis, Lait fermenté, Cultured milk, Leche fermentada, Listeria monocytogenes, Origine microbienne, Microbial origin, Origen microbiano, Produit naturel, Natural product, Producto natural, Souche pathogène, Pathogen strain, and Cepa patógena

Bacteriocin-producing (Bac+) Lactococcus lactis ssp. lactis CCMM/IAV/BK1 isolated from traditional lben was used in the preparation of lben from pasteurized milk to assess its potential inhibitory activity against Listeria monocytogenes ATCC 7644. Production of bacteriocin (arbitrary units, AU) in MRS broth fortified with yeast extract (MRSY) in a fermentor under controlled and uncontrolled pH conditions was also investigated. This Bac+ strain yielded about 35 times more bacteriocin when the pH was maintained constant at 6.5 than under varying pH conditions. To test the effect of in situ bacteriocin production against L. monocytogenes, lben was made from cow's milk artificially contaminated with approximately 107 cfu/mL and fermented with a mixed mesophilic starter culture consisting of the lactococcal Bac+ organism and Lc. lactis ssp. lactis biovar diacetylactis 66, a diacetyl-producing strain, in a ratio of 1 : 1. Numbers of L. monocytogenes were monitored during fermentation and storage of lben at refrigeration temperature (c. 7°C) for up to 6 days. Performances of the Bac+ starter were compared to those of an isogenic Bac- derivative strain obtained from the Bac+ starter by curing with ethidium bromide. The results showed that the amount of L. monocytogenes decreased to below the detectable level in a 1-mL sample within 24 h of storage at 7°C in lben fermented with the Bac+ starter culture. On the contrary, L. monocytogenes survived for 6 days of storage at 7°C in lben made with the Bac- starter. The Bac+ wild strain of the starter studied could be adequately used to produce lben or similar indigenous fermented milks of improved hygienic quality on an industrial scale. Alternatively, it could be used as an adjunct in minimally processed products or in products obtained from raw milk to add a safety factor.

Bacteriocin-like substances, Listeria monocytogenes, Enterococcus spp., Peruvian traditional cheese, Life sciences :: Microbiology, and Sciences du vivant :: Microbiologie

The aim of this work was to isolate and to characterize strains of lactic acid bacteria (LAB) with bacteriocin-like inhibitory activity from 27 traditional cheeses artisanal-produced obtained from different Peruvian regions. Twenty Gram+ and catalasenegative strains among 2,277 isolates exhibited bacteriocin-like inhibitory activity against Listeria monocytogenes CWBIB2232 as target strain. No change in inhibitory activity was observed after organic acid neutralization and treatment with catalase of the cell-free supernatant (CFS). The proteinic nature of the antimicrobial activity was confirmed for the twenty LAB strains by proteolytic digestion of the CFS. Two strains, CWBI-B1431 and CWBI-B1430, with the best antimicrobial activity were selected for further researches. These strains were taxonomically identified by phenotypic and genotypic analyses as Enterococcus mundtii (CWBI-B1431) and Enterococcus faecium (CWBI-B1430). The two strains were sensitive to vancomycin (MIC < 2 μg.ml-1) and showed absence of haemolysis.

Psychrophilic, γ-Decalactone, Castor oil, Mesophilic, Rhodotorula aurantiaca, Life sciences, Biotechnology, Microbiology, Sciences du vivant, Biotechnologie, and Microbiologie

Among 18 psychrophilic strains isolated near the Antarctic Station, the psychrophilicstrain Rhodotorula aurantiaca A19 was selected for its ability of growth and γ-decalactone production at low temperatures. The effects of temperature, initial pH, and castoroil concentration on the growth and γ-decalactone production by a psychrophilic and amesophilic strain of R. aurantiaca were investigated. The highest γ-decalactone productionin flasks (5.8 g/l) was obtained with the strain A19 at 14 °C and initial pH 7.0 in mediumcontaining 20 g/l castor oil. On the other hand, these factors did not affect the production ofγ-decalactone by the mesophilic strain. In fermentor, a γ-decalactone concentration of 6.6 g/lwas reached with the strain A19, whereas a maximum of 0.1 g/l was obtained with themesophilic strain. Our results suggest that the ability to synthesize γ-decalactone is aparticularity of the strain A19, since the mesophilic strain (no. 30645) produced small amounts,and the other (no. 31354) did not exhibit this property. It is, to our knowledge, the first report of γ-decalactone production by R. aurantiaca and furthermore by a psychrophilic yeast strain.Moreover, the amount of γ-decalactone obtained in fermentor with the strain 19 was on theorder of concentrations usually described in patents.

lipases, immobilization, hydrolyse, transesterification, interesteritication., Life sciences, Agriculture & agronomy, Environmental sciences & ecology, Sciences du vivant, Agriculture & agronomie, and Sciences de l’environnement & écologie

Lipases are able to catalyse the hydrolysis of glyceridic esters in aqueous media and the synthesis of esters in non-aqueous media. They are thus able to catalyse numerous reactions of industrial interest. Whether it is by inclusion, by adsorption or by covalent link, the immobilisation of lipases aims at conferring them a good stability that enables a reuse of the enzymes after a reaction and the development of continuous processes. The reactions of triglycerides hydrolysis constitute main applications for immobilised lipases, however their use in different types of esterification reactions has also arose: there exist processes involving reactions of transesterification, of interesterification or of esters synthesis. The production of structured lipids by interesterification is one example. Although the reaction conditions dissent from those of hydrolysis, the same lipases have been used in both cases. A lipase specifically adapted for esterification though would be a highly capable tool: a series of strategies is in progress in order to reach this goal.

Life sciences, Microbiology, Sciences du vivant, and Microbiologie

3-galactosidase, LIP2 regulation, lipase, methyl oleate, bioreactor, Life sciences, Microbiology, Biotechnology, Sciences du vivant, Microbiologie, and Biotechnologie

Methyl oleate was used as a primary carbon source and as an alternative inducer for the production of an extracellular lipase, Lip2, in Y. lipol.vtica strain LgX64.81 grown in a 20-1 bioreactor. The lipase-encoding gene, LIP2, was investigated during culture on methyl oleate using a pLIP2-LacZ reporter fusion and we provide evidence for the involvement of methyl oleate in its regulation.