Pre-inoculation enrichment procedure enhances the performance of bacteriocinogenic Lactococcus lactis meat starter culture

2001 ◽  
Vol 64 (1-2) ◽  
pp. 151-159 ◽  
Author(s):  
Amalia G.M. Scannell ◽  
Gerhard Schwarz ◽  
Colin Hill ◽  
R.Paul Ross ◽  
Elke K. Arendt
Keyword(s):  
Lactococcus Lactis ◽  
Starter Culture ◽  
Enrichment Procedure

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.

scholarly journals Over-expressed CmbT multidrug resistance transporter improves the fitness of Lactococcus lactis

Genetika ◽  
2013 ◽  
Vol 45 (1) ◽  
pp. 197-206 ◽  
Author(s):  
Brankica Filipic ◽  
Branko Jovcic ◽  
Gordana Uzelac ◽  
Marija Miljkovic ◽  
Jelena Antic-Stankovic ◽  
...  
Keyword(s):  
Growth Rate ◽  
Multidrug Resistance ◽  
Lactococcus Lactis ◽  
Starter Culture ◽  
Growth Curves ◽  
Host Bacterium ◽  
Control Strain ◽  
Toxic Compounds ◽  
Over Expression ◽  
Multidrug Resistance Transporter

The influence of the over-expression of CmbT multidrug resistance transporter on the growth rate of Lactococcus lactis NZ9000 was studied. L. lactis is a lactic acid bacteria (LAB) widely used as a starter culture in dairy industry. Recently characterized CmbT MDR transporter in L. lactis confers resistance to a wide variety of toxic compounds as well as to some clinically relevant antibiotics. In this study, the cmbT gene was over-expressed in the strain L. lactis NZ9000 in the presence of nisin inducer. Over-expression of the cmbT gene in L. lactis NZ9000 was followed by RT-PCR. The obtained results showed that the cmbT gene was successfully over-expressed by addition of sub-inhibitory amounts of nisin. Growth curves of L. lactis NZ9000/pCT50 over-expressing the cmbT gene and L. lactis NZ9000 control strain were followed in the rich medium as well as in the chemically defined medium in the presence solely of methionine (0.084 mM) or mix of methionine and cysteine (8.4 mM and 8.2 mM, respectively). Resulting doubling times revealed that L. lactis NZ9000/pCT50 had higher growth rate comparing to the control strain. This could be a consequence of the CmbT efflux activity, which improves the fitness of the host bacterium through the elimination of toxic compounds from the cell.

Changes in Galactose and Lactic Acid Content of Sweet Whey during Storage

2004 ◽  
Vol 67 (2) ◽  
pp. 403-406 ◽  
Author(s):  
R. D. RAO ◽  
W. L. WENDORFF ◽  
K. SMITH
Keyword(s):  
Lactic Acid ◽  
Lactococcus Lactis ◽  
Lactic Acid Production ◽  
Starter Culture ◽  
Storage Conditions ◽  
Starter Cultures ◽  
Lactobacillus Helveticus ◽  
Lactobacillus Delbrueckii ◽  
The Other ◽  
Time Period

Whey is often stored or transported for a period of time prior to processing. During this time period, galactose and lactic acid concentrations may accumulate, reducing the quality of spray-dried whey powders in regard to stickiness and agglomeration. This study surveyed industry samples of Cheddar and mozzarella cheese whey streams to determine how galactose and lactic acid concentrations changed with storage at appropriate (4°C) and abuse (37.8°C) temperatures. Samples stored at 4°C did not exhibit significant increases in levels of lactic acid or galactose. Mozzarella whey accumulated the greatest amount of galactose and lactic acid with storage at 37.8°C. Whey samples derived from cheese made from single strains of starter culture were also evaluated to determine each culture's contribution to galactose and lactic acid production. Starter cultures evaluated included Streptococcus salivarius ssp. thermophilus, Lactobacillus helveticus, Lactobacillus delbrueckii ssp. bulgaricus, Lactococcus lactis ssp. cremoris, and Lactococcus lactis ssp. lactis. Whey derived from L. helveticus accumulated a significantly greater amount of lactic acid upon storage at 37.8°C as compared with the other cultures. Galactose accumulation was significantly decreased in whey from L. lactis ssp. lactis stored at 37.8°C in comparison with the other cultures. Results from this study indicate that proper storage conditions (4°C) for whey prevent accumulation of galactose and lactic acid while the extent of accumulation during storage at 37.8°C varies depending on the culture(s) used in cheese production.

scholarly journals Generation of lactose and protease positive probiotic Lacticaseibacillus rhamnosus GG by conjugation with Lactococcus lactis NCDO 712

2021 ◽  
Author(s):  
Nazar Hussain ◽  
Ran Li ◽  
Timo M. Takala ◽  
Muhammad Tariq ◽  
Arsalan H. Zaidi ◽  
...  
Keyword(s):  
Lactococcus Lactis ◽  
Dairy Products ◽  
Milk Protein ◽  
Starter Culture ◽  
Microscopic Analysis ◽  
Probiotic Strain ◽  
Pcr Primers ◽  
Sole Source ◽  
Probiotic Bacterium ◽  
Specific Pcr

Lacticaseibacillus rhamnosus GG (LGG) is the most studied probiotic bacterium in the world. It is used as a probiotic supplement in many foods, including various dairy products. However, LGG grows poorly in milk, as it neither metabolizes the main milk carbohydrate lactose, nor degrades the major milk protein casein effectively. In this study, we made L. rhamnosus GG lactose and protease positive by conjugation with the dairy Lactococcus lactis strain NCDO 712 carrying the lactose-protease plasmid pLP712. A lactose hydrolyzing transconjugant colony was obtained on agar containing lactose as the sole source of carbohydrates. By microscopic analysis and PCR with LGG- and pLP712-specific primers, the transconjugant was confirmed to be originated from LGG, and to carry the plasmid pLP712. The transconjugant was named L. rhamnosus LAB49. Isolation of plasmids revealed that not only pLP712, but also other plasmids had been transferred from L. lactis into LGG during conjugation. With plasmid-specific PCR primers, four additional lactococcal plasmids were detected in LAB49. Proteolytic activity assay and SDS-PAGE analysis verified that L. rhamnosus LAB49 effectively degraded β-casein. In contrast to its parental strain LGG, the ability of LAB49 to metabolize lactose and degrade casein enabled strong and fast growth in milk. As strains with new properties made by conjugation are not regarded as GMOs, L. rhamnosus LAB49 could be beneficial in dairy fermentations as a probiotic starter culture. Importance Probiotic strain Lacticaseibacillus rhamnosus GG (LGG) is widely sold on market as a probiotic or added as supplement in dairy foods because of its benefits in human health. However, due to the deficiency of lactose and casein utilization, LGG does not grow well in milk. On the other hand, lactose intolerance and cow's milk protein allergy are the two major problems related to milk consumption. One option to help with these two conditions is the use of probiotic or lactose and casein hydrolyzing bacteria in dairy products. The purpose of this study was to equip LGG with lactose/casein hydrolyzing ability by bacterial conjugation. As a result, we generated a non-GMO LGG derivative with improved properties and better growth in milk.

Identification of Four Phage Resistance Plasmids from Lactococcus lactis subsp. cremorisHO2

1999 ◽  
Vol 65 (4) ◽  
pp. 1540-1547 ◽  
Author(s):  
Amanda Forde ◽  
Charles Daly ◽  
Gerald F. Fitzgerald
Keyword(s):  
Lactococcus Lactis ◽  
Plasmid Dna ◽  
Starter Culture ◽  
Phage Resistance ◽  
Modification System ◽  
Restriction Modification System ◽  
Resistance Plasmids ◽  
Lactose Utilization ◽  
Blocking Mechanism ◽  
Restriction Modification

ABSTRACT The bacteriophage-host sensitivity patterns of 16 strains ofLactococcus lactis originally isolated from a mixed strain Cheddar cheese starter culture were determined. Using phages obtained from cheese factory whey, four of the strains were found to be highly phage resistant. One of these isolates, Lactococcus lactissubsp. cremoris HO2, was studied in detail to determine the mechanisms responsible for the phage insensitivity phenotypes. Conjugal transfer of plasmid DNA from strain HO2 allowed a function to be assigned to four of its six plasmids. A 46-kb molecule, designated pCI646, was found to harbor the lactose utilization genes, while this and plasmids of 58 kb (pCI658), 42 kb (pCI642), and 4.5 kb (pCI605) were shown to be responsible for the phage resistance phenotypes observed against the small isometric-headed phage φ712 (936 phage species) and the prolate-headed phage φc2 (c2 species). pCI658 was found to mediate an adsorption-blocking mechanism and was also responsible for the fluffy pellet phenotype of cells containing the molecule. pCI642 and pCI605 were both shown to be required for the operation of a restriction-modification system.

scholarly journals Effects of starter culture and storage on volatile profiles and sensory characteristics of yogurt or cream butter

2020 ◽  
Vol 70 (3) ◽  
pp. 184-200
Author(s):  
Engin Gundogdu ◽  
Songul Cakmakci ◽  
Ali Adnan Hayaloglu
Keyword(s):  
Volatile Compounds ◽  
Lactococcus Lactis ◽  
Leuconostoc Mesenteroides ◽  
Starter Culture ◽  
Hexanoic Acid ◽  
Sensory Properties ◽  
Sensory Characteristics ◽  
Volatile Profiles ◽  
And Storage ◽  
General Acceptability

In this study volatile compounds and sensory properties of butter produced from cream or yogurt using Lactococcus lactis subsp. lactis biovar. diacetylactis or Leuconostoc mesenteroides subsp. cremoris as well as a mixture of these two bacteria were investigated over 60 days. A total of 10 esters, 6 aldehydes, 11 ketones, 16 alcohols, 6 acids, 2 sulphides, 3 terpenes, and 3 miscellaneous compounds were detected. There were more volatile compounds in cream butter than in yogurt butter. While S-methyl thioacetate was only found in yogurt butter samples, hexanal, ethanol, 2-nonanone, 2-pentanone, 2-heptanone, acetic, butanoic (butyric) and hexanoic acid were the most abundant volatiles in both cream and yogurt butter. The results showed that the use of starter in the manufacturing of yogurt butter, which is traditionally produced without starters, affected the volatile compounds and sensory properties. The highest general acceptability scores were given to the butter samples containing mixed cultures at the end of storage.

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