scholarly journals Изучение разнообразия ассоциаций фагов гомологичных молочнокислым бактериям

2017 ◽  
Vol 7 (4) ◽  
pp. 197-206
Author(s):  
N. I. Odegov ◽  
R. V. Dorofeev ◽  
A. N. Irkitova ◽  
I. A. Funk ◽  
T. N. Orlova ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Experimental Studies ◽  
Biological Properties ◽  
Starter Cultures ◽  
Lytic Activity ◽  
Genetic Determinants ◽  
Lactococcus Lactis Subsp ◽  
Culture Characteristics ◽  
Siberian Research Institute ◽  
Activity Spectrum

Information on the ecology of the "phage-bacterial host" system is given. The interaction of cultures of lactococci from the collection of the Siberian Research Institute of Cheese with associations of phages was investigated. Infection of sensitive cells with bacteriophage led to cell lysis, which was manifested by negative colonies on the lawn of a lactococcal culture. Characteristics of the biological properties of bacteriophages in the composition of phage associations are given (lytic activity, spectrum of lytic activity, specificity of action). Differentiation of species lysotypes of bacteriophages of mesophilic lactococci, selected at a single cheese enterprise in the Altai Territory was noted. The index of the lytic activity of the investigated phage associations ranged from 0.19 (sample of Lactococcus lactis subsp. Lactis biovar diacetylactis) to 0.24 (sample of Lactococcus lactis subsp. Lactis) from studied strains. The value of the lyotype updated coefficient for the entire array of data varied from 0.25 to 1.00. It is concluded that the specificity of cheese biotechnology together with the evolutionary and genetic determinants of the microworld predetermine a constant high risk of cell phagolysis of starter cultures. Experimental studies confirmed the need to consider the phagocyte of lactic acid bacteria in biotechnology.

Persistence of Escherichia coli O157:H7 in Dairy Fermentation Systems

1998 ◽  
Vol 61 (12) ◽  
pp. 1602-1608 ◽  
Author(s):  
SEAN S. DINEEN ◽  
KAZUE TAKEUCHI ◽  
JANE E. SOUDAH ◽  
KATHRYN J. BOOR
Keyword(s):  
Escherichia Coli ◽  
Lactococcus Lactis ◽  
Dairy Products ◽  
Starter Cultures ◽  
Escherichia Coli O157 ◽  
Potential Health ◽  
E Coli ◽  
Lactococcus Lactis Subsp ◽  
Fermented Dairy Products ◽  
Fermented Dairy

We examined (i) the persistence of Escherichia coli O157:H7 as a postpasteurization contaminant in fermented dairy products; (ii) the ability of E. coli O157:H7 strains with and without the general stress regulatory protein, RpoS, to compete with commercial starter cultures in fermentation systems; and (iii) the survival of E. coli O157:H7 in the yogurt production process. In commercial products inoculated with 103 CFU/ml, E. coli O157:H7 was recovered for up to 12 days in yogurt (pH 4.0), 28 days in sour cream (pH 4.3), and at levels >102 CFU/ml at 35 days in buttermilk (pH 4.1). For the starter culture competition trials, the relative inhibition of E. coli O157:H7 in the experimental fermentation systems was, in decreasing order, thermophilic culture mixture, Lactobacillus delbrueckii subsp. bulgaricus R110 alone, Lactococcus lactis subsp. lactis D280 alone, Lactococcus lactis subsp. cremoris D62 alone, and Streptococcus thermophilus C90 alone showing the least inhibition. Recovery of the rpoS mutant was lower than recovery of its wild-type parent by 72 h or earlier in the presence of individual starter cultures. No E. coli O157:H7 were recovered after the curd formation step in yogurt manufactured with milk inoculated with 105 CFU/ml. Our results show that (i) postprocessing entry of E. coli O157:H7 into fermented dairy products represents a potential health hazard; (ii) commercial starter cultures differ in their ability to reduce E. coli O157:H7 CFU numbers in fermentation systems; and (iii) the RpoS protein appears to most effectively contribute to bacterial survival in the presence of conditions that are moderately lethal to the cell.

scholarly journals Autochthonous Starter Effect on the Microbiological, Physicochemical and Sensorial Characteristics of Moroccan Goat’s Milk Cheeses

2014 ◽  
Vol 4 (1) ◽  
pp. 343-351
Author(s):  
Ouiam El Galiou ◽  
Juan Antonio Centeno ◽  
Said Zantar ◽  
Mohammed Bakkali ◽  
Javier Carballo ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Starter Cultures ◽  
Lactobacillus Paracasei ◽  
Sensory Characteristics ◽  
Total Solids ◽  
Lactococcus Lactis Subsp ◽  
Ph Values

The effect of adding four Lactococcus lactis subsp. Lactis, Lactococcus lactis subsp. lactis Bv. diacetylactis and Lactobacillus paracasei autochthonous strains as single starters (A and B) on the microbiological, physicochemical and sensory characteristics of Moroccan goat’s milk cheese was investigated. Batches with a commercial starter (C) and with raw goat’s milk without starter (D) were also made as controls. The results indicated that the different starter cultures used significantly affected the compositional characteristics of Moroccan goat’s cheese. At the first day of ripening, the pH values of cheeses manufactured with any type of starter were significantly higher than those made without starter. No significant differences (P >0.05) in values of total solids (T.S.), proteins, ash, FAT and lactose content were found between any of the batches after 7 days of ripening. The autochthonous starters in Moroccan cheesemaking were successful at reducing the levels of coliforms earlier in ripening than in cheeses made without starter and even in those made with the commercial starter. These results suggest that the combined activity of L. Lactis subsp. lactis, L. Lactis. subsp. Lactis bv. diacetylactis and L. paracasei, produces cheese with good sensory characteristics.

scholarly journals Evaluation of Some Factors with Significant Influence on Functionality and Viability of Probiotic Strains LA-5 ® and L. Casei 431 ® in Multiple Starter Cultures in Mesophilic Fermented Milk

2012 ◽  
Vol 69 (2) ◽  
Author(s):  
Daniela PARASCHIV ◽  
Aida VASILE
Keyword(s):  
Lactococcus Lactis ◽  
Fermented Milk ◽  
Starter Cultures ◽  
Milk Product ◽  
Lactococcus Lactis Subsp ◽  
Commercial Code ◽  
Long Time ◽  
Probiotic Strains

Abstract.  For a very long time, probiotics have been selected on the basis of their suitability to food’s environment and technological procedures, as well as survival ability in vitro and also in vivo. These criteria are still used. The aim of this study was to select, using the Plakett-Burman design of experiments model, of three significant factors, which influence the multiplication ability and viability of probiotic strains Lactobacillus acidophilus (commercial code LA-5®) and Lactobacillus casei subsp. paracasei (commercial code L. casei 431®) in fermented mesophilic milk product (commercial named Sana) obtained by fermentation with a multiple culture with mesophilic lactic starter Flora Danica Chr. Hansen commercial starters (Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. diacetylactis and Leuconostoc mesenteroides subsp. cremoris). By statistical analysis the most important factors (independent variables)  with influence on the probiotic bacteria were selected for the optimized. These are the temperature of fermentation; the ratio between probiotic strains and Flora Danica and the addition of prebiotic Fagopyrum esculentum flour. In the future experiments the optimum values of these parameters will be optimized by using response surface methodology, in order to establish the conditions in which can be obtain the mesophilic fermented milk products with probiotic action in vivo. 

Note: Effect of Different Cultures on Physico-chemical and Sensory Properties of Low-fat Herby Cheese

2006 ◽  
Vol 12 (5) ◽  
pp. 423-428 ◽  
Author(s):  
Z. Tarakci ◽  
E. Kucukoner
Keyword(s):  
Lactococcus Lactis ◽  
Starter Cultures ◽  
Water Soluble ◽  
Lactobacillus Delbrueckii ◽  
Soluble Nitrogen ◽  
Low Fat ◽  
Lactococcus Lactis Subsp ◽  
Physico Chemical ◽  
Comparison Results ◽  
Low Fat Cheese

The effect of three commercially available traditional cultures namely yoghurt cultures ( Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus), cheese cultures ( Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris) and helveticus culture ( Lactobacillus helveticus) on the physico-chemical and sensorial characteristics of low-fat herby cheese were investigated during ripening for 90 days. Low-fat cheese and full-fat cheese without starter culture were also produced, for comparison. Results indicated that addition of the different starter cultures on low-fat cheeses had no significant (P 0.05) effect in compositional (moisture, fat in matter, titratable acidity and pH) and biochemical (water-soluble nitrogen (WSN)), trichloroacetic acid-soluble nitrogen (TCA-SN) and phosphotungstic acid-soluble nitrogen (PTA-SN) compounds in comparison with the low-fat control cheese. The low-fat cheeses made with the starter cultures had slightly greater scores for appearance and colour, body-texture, flavour and acceptability than the control low-fat cheese after 30, 60 and 90 days ripening but differences were not significant (P 0.05). Full-fat cheeses had greater sensory scores than low-fat cheeses.

Preparation of low-lactose fermented milk products for baby food

2021 ◽  
pp. 23-26
Author(s):  
Татьяна Алексеевна Антипова ◽  
Светлана Валерьевна Фелик ◽  
Надежда Леонидовна Андросова ◽  
Сергей Владимирович Симоненко
Keyword(s):  
Lactococcus Lactis ◽  
Lactobacillus Acidophilus ◽  
Fermentation Process ◽  
Fermented Milk ◽  
Starter Cultures ◽  
Lactobacillus Bulgaricus ◽  
Lactose Hydrolysis ◽  
Milk Product ◽  
Lactococcus Lactis Subsp ◽  
Lactose Fermentation

Статья посвящена получению кисломолочного продукта для питания детей с лактазной недостаточностью. Одним из наиболее распространенных способов получения низколактозных продуктов является применение гидролиза лактозы с использованием ферментных препаратов. Целью работы было изучение процесса сквашивания низколактозного молочного продукта. Учитывая, что при использовании методов ферментирования лактозы продукт приобретает выраженный сладкий вкус, обусловленный наличием глюкозы, требовалось установить заданное количество лактозы при достижении оптимальных органолептических показателей. Результаты исследований свидетельствуют об изменении органолептических и физико-химических показателей образцов в результате гидролиза лактозы. Вкусовые проявления сладости в продукте появляются при степени гидролиза лактозы 50 % и усиливаются при дальнейшем проведении гидролиза. Для проведения процесса сквашивания применяли следующие виды заквасочных культур: Lactobacillus acidophilus, Treptococcus thermophilus, Lactobacillus bulgaricus, Streptococcus thermophiles, Lactococcus lactis subsp. lactis и Lactococcus lactis subsp. Сremoris. Процесс сквашивания во всех образцах низколактозного молока имеет свои особенности, характерные для используемой заквасочной культуры. Следует отметить, что заквасочные культуры, включающие ацидофильную палочку, интенсифицируют процесс сквашивания исследуемых образцов. Содержание лактозы после окончания процесса сквашивания в исследуемых образцах составило 1,35; 1,4 %, что соответствует требованиям ТР ТС 027/2012 «О безопасности отдельных видов специализированной пищевой продукции, в том числе диетического лечебного и диетического профилактического питания». The article is devoted to the preparation of a fermented milk product for the nutrition of children with lactase deficiency. One of the most common methods of obtaining low-lactose products is the use of lactose hydrolysis using enzyme preparations. The aim of the work was to study the process of fermentation of low-lactose dairy product. Given that when using the methods of lactose fermentation, the product acquires a pronounced sweet taste due to the presence of glucose, it was necessary to set a given amount of lactose when achieving optimal organoleptic parameters. The results of the studies indicate a change in the organoleptic and physico-chemical parameters of the samples as a result of lactose hydrolysis. The taste manifestations of sweetness in the product appear at the degree of lactose hydrolysis of 50 % and increase with further hydrolysis. The following types of starter cultures were used for the fermentation process: Lactobacillus acidophilus; Treptococcus thermophilus, Lactobacillus bulgaricus; Streptococcus thermophiles; Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. Cremoris. The fermentation process in all samples of low-lactose milk has its own characteristics characteristic of the starter culture used. It should be noted that starter cultures, including Acidophilus bacillus, intensify the process of fermentation of the studied samples. The lactose content after the end of the fermentation process in the studied samples was 1.35; 1.4 %, which corresponds to the requirements of TR CU 027/2012 «On the safety of certain types of specialized food products, including dietary therapeutic and dietary preventive nutrition».

Cell Growth Density and Nisin A Activity of the Indigenous Lactococcus lactis subsp. cremoris M78 Costarter Depend Strongly on Inoculation Levels of a Commercial Streptococcus thermophilus Starter in Milk: Practical Aspects for Traditional Greek Cheese Processors

2020 ◽  
Vol 83 (3) ◽  
pp. 542-551
Author(s):  
JOHN SAMELIS ◽  
ATHANASIA KAKOURI
Keyword(s):  
Lactococcus Lactis ◽  
Streptococcus Thermophilus ◽  
Raw Milk ◽  
Starter Cultures ◽  
Competitive Growth ◽  
Population Densities ◽  
Relative Population ◽  
Lactococcus Lactis Subsp ◽  
Pure Cultures

ABSTRACT Mixed thermophilic and mesophilic commercial starter cultures (CSCs), particularly those including Streptococcus thermophilus as a primary milk acidifier, have been found to reduce growth and counteract in situ nisin A (NisA+) antilisterial effects by the novel, indigenous Lactococcus lactis subsp. cremoris M78 costarter in traditional Graviera thermized milk cheese curds. Therefore, this model challenge study evaluated growth and in situ NisA+ activity of strain M78 in coculture with S. thermophilus ST1 singly in sterilized raw milk (SRM). Strain ST1, derived from a CSC for cheese, was challenged at two inoculation levels (5 and 7 log CFU/mL) in SRM against 6 and 3 log CFU/mL of strain M78 and Listeria monocytogenes, respectively. Pure cultures of each strain and cocultures of strain ST1 with the CSC L. lactis LL2, in replacement of strain M78, served as controls. At the high (7-log) inoculation level, the rapid, competitive growth (>9.3 log CFU/mL) of S. thermophilus ST1 reduced growth of both L. lactis by at least 10-fold; the industrial strain LL2 retained slightly higher relative population densities (7.4 to 9.1%) than the wild NisA+ strain M78 (3.8 to 5.6%) after 6 h at 37°C, followed by an additional 66 h of incubation at 22°C. In full contrast, at the low (5-log) inoculation level, S. thermophilus ST1 failed to predominate in SRM at 6 h; thus, the starter lactic acid bacteria populations were reversed in favor of L. lactis. Notably, strain M78 retained higher relative population densities (83.0 to 90.1%) than the CSC strain LL2 (80.3 to 85.2%) at 22°C. Moreover, at the 5-log ST1 level, the direct and deferred in situ NisA+ activities of strain M78 were at similar levels with its pure culture with L. monocytogenes in SRM, whereas at the 7-log ST1 level, the respective NisA+ effects were counteracted. Hence, 10- to 100-fold lowered inoculation levels of CSC S. thermophilus are required to enhance the performance of the M78 costarter in traditional Greek cheese technologies. HIGHLIGHTS

Growth, nisA Gene Expression, and In Situ Activity of Novel Lactococcus lactis subsp. cremoris Costarter Culture in Commercial Hard Cheese Production

2017 ◽  
Vol 80 (12) ◽  
pp. 2137-2146 ◽  
Author(s):  
Dimitrios Noutsopoulos ◽  
Athanasia Kakouri ◽  
Eleftheria Kartezini ◽  
Dimitrios Pappas ◽  
Efstathios Hatziloukas ◽  
...  
Keyword(s):  
Gene Expression ◽  
Lactococcus Lactis ◽  
Starter Culture ◽  
Fold Increase ◽  
Raw Milk ◽  
Good Growth ◽  
Lactococcus Lactis Subsp ◽  
Quantitative Expression ◽  
Hard Cheese

ABSTRACT This study evaluated in situ expression of the nisA gene by an indigenous, nisin A–producing (NisA+) Lactococcus lactis subsp. cremoris raw milk genotype, represented by strain M78, in traditional Greek Graviera cheeses under real factory-scale manufacturing and ripening conditions. Cheeses were produced with added a mixed thermophilic and mesophilic commercial starter culture (CSC) or with the CSC plus strain M78 (CSC+M78). Cheeses were sampled after curd cooking (day 0), fermentation of the unsalted molds for 24 h (day 1), brining (day 7), and ripening of the brined molds (14 to 15 kg each) for 30 days in a fully controlled industrial room (16.5°C; 91% relative humidity; day 37). Total RNA was directly extracted from the cheese samples, and the expression of nisA gene was evaluated by real-time reverse transcription PCR (qRT-PCR). Agar overlay and well diffusion bioassays were correspondingly used for in situ detection of the M78 NisA+ colonies in the cheese agar plates and antilisterial activity in whole-cheese slurry samples, respectively. Agar overlay assays showed good growth (>8 log CFU/g of cheese) of the NisA+ strain M78 in coculture with the CSC and vice versa. The nisA expression was detected in CSC+M78 cheese samples only, with its expression levels being the highest (16-fold increase compared with those of the control gene) on day 1, followed by significant reduction on day 7 and almost negligible expression on day 37. Based on the results, certain intrinsic and mainly implicit hurdle factors appeared to reduce growth prevalence rates and decrease nisA gene expression, as well as the nisin A–mediated antilisterial activities of the NisA+ strain M78 postfermentation. To our knowledge, this is the first report on quantitative expression of the nisA gene in a Greek cooked hard cheese during commercial manufacturing and ripening conditions by using a novel, rarely isolated, indigenous NisA+ L. lactis subsp. cremoris genotype as costarter culture.

Location and characterization of aminopeptidase N in Lactococcus lactis subsp. cremoris HP

1992 ◽  
Vol 37 (1) ◽  
pp. 46-54 ◽  
Author(s):  
Fred A. Exterkate ◽  
Marian de Jong ◽  
Gerrie J. C. M. de Veer ◽  
Ronald Baankreis
Keyword(s):  
Lactococcus Lactis ◽  
Aminopeptidase N ◽  
Lactococcus Lactis Subsp
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