scholarly journals Insertional Mutagenesis To Generate Lantibiotic Resistance in Lactococcus lactis

2007 ◽  
Vol 73 (14) ◽  
pp. 4677-4680 ◽  
Author(s):  
Caitriona M. Guinane ◽  
Paul D. Cotter ◽  
Elaine M. Lawton ◽  
Colin Hill ◽  
R. Paul Ross
Keyword(s):  
Lactococcus Lactis ◽  
Pathogenic Bacteria ◽  
Insertional Mutagenesis ◽  
Starter Cultures ◽  
Food Spoilage ◽  
Genetic Loci ◽  
The Creation ◽  
Derivatives Of

ABSTRACT While the potential emergence of food spoilage and pathogenic bacteria with resistance to lantibiotics is a concern, the creation of derivatives of starter cultures and adjuncts that can grow in the presence of these antimicrobials may have applications in food fermentations. Here a bank of Lactococcus lactis IL1403 mutants was created and screened, and a number of novel genetic loci involved in lantibiotic resistance were identified.

scholarly journals Unleashing natural competence inLactococcus lactisby induction of the competence regulator ComX

2017 ◽  
Author(s):  
Joyce Mulder ◽  
Michiel Wels ◽  
Oscar P. Kuipers ◽  
Michiel Kleerebezem ◽  
Peter A. Bron
Keyword(s):  
Lactococcus Lactis ◽  
Genetic Manipulation ◽  
Bacterial Species ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Natural Competence ◽  
Competence Gene ◽  
Gene Sets ◽  
Novel Traits ◽  
Derivatives Of

AbstractIn biotechnological work horses likeStreptococcus thermophilusandBacillus subtilisnatural competence can be induced, which facilitates genetic manipulation of these microbes. However, in strains of the important dairy starterLactococcus lactisnatural competence has not been established to date. However,in silicoanalysis of complete genome sequences of 43L. lactisstrains revealed complete late-competence gene-sets in 2L. lactissubspeciescremorisstrains (KW2 and KW10) and 8L. lactissubspecieslactisstrains, including the model strain IL1403 and the plant-derived strain KF147. The remainder of the strains, including all dairy isolates, displayed genomic decay in one or more of the late competence genes. Nisin-controlled expression of the competence regulatorcomXinL. lactissubsp.lactisKF147 resulted in the induction of expression of the canonical competence regulon, and elicited a state of natural competence in this strain. By contrast,comXexpression inL. lactisNZ9000, predicted to encode an incomplete competence gene-set, failed to induce natural competence. Moreover, mutagenesis of thecomEA-ECoperon in strain KF147, abolished thecomXdriven natural competence, underpinning the involvement of the competence machinery. Finally, introduction of nisin-induciblecomXexpression intonisRK-harboring derivatives of strains IL1403 and KW2 allowed the induction of natural competence also in these strains, expanding this phenotype to otherL. lactisstrains of both subspecies.Significance statementSpecific bacterial species are able to enter a state of natural competence in which DNA is taken up from the environment, allowing the introduction of novel traits. Strains of the speciesLactococcus lactisare very important starter cultures for the fermentation of milk in the cheese production process, where these bacteria contribute to the flavor and texture of the end-product. The activation of natural competence in this industrially relevant organism can accelerate research aiming to understand industrially relevant traits of these bacteria, and can facilitate engineering strategies to harness the natural biodiversity of the species in optimized starter strains.

Inhibition of food-spoilage and foodborne pathogenic bacteria by a nisin Z-producing Lactococcus lactis subsp. lactis KT2W2L

LWT ◽  
2017 ◽  
Vol 82 ◽  
pp. 170-175 ◽  
Author(s):  
Noraphat Hwanhlem ◽  
Teodora Ivanova ◽  
Thomas Haertlé ◽  
Emmanuel Jaffrès ◽  
Xavier Dousset
Keyword(s):  
Lactococcus Lactis ◽  
Pathogenic Bacteria ◽  
Food Spoilage ◽  
Lactococcus Lactis Subsp ◽  
Nisin Z ◽  
Foodborne Pathogenic Bacteria

Varying influence of the autolysin, N-acetyl muramidase, and the cell envelope proteinase on the rate of autolysis of six commercial Lactococcus lactis cheese starter bacteria grown in milk

2000 ◽  
Vol 67 (4) ◽  
pp. 585-596 ◽  
Author(s):  
SELVARANI GOVINDASAMY-LUCEY ◽  
PRAMOD K. GOPAL ◽  
PATRICK A. SULLIVAN ◽  
CHRISTOPHER J. PILLIDGE
Keyword(s):  
Lactococcus Lactis ◽  
Cell Walls ◽  
Cell Envelope ◽  
Laboratory Strain ◽  
Proteolytic Cleavage ◽  
Zymogram Analysis ◽  
Sds Page ◽  
Derivatives Of ◽  
Free Strains

The autolysin, N-acetyl muramidase (AcmA), of six commercial Lactococcus lactis subsp. cremoris starter strains and eight Lc. lactis subsp. cremoris derivatives or plasmid-free strains was shown by renaturing SDS-PAGE (zymogram analysis) to be degraded by the cell envelope proteinase (lactocepin; EC 3.4.21.96) after growth of strains in milk at 30 °C for 72 h. Degradation of AcmA was less in starter strains and derivatives producing lactocepin I/III (intermediate specificity) than in strains producing lactocepin I. This supports previous observations on AcmA degradation in derivatives of the laboratory strain Lc. lactis subsp. cremoris MG1363 (Buist et al. Journal of Bacteriology180 5947–5953 1998). In contrast to the MG1363 derivatives, however, the extent of autolysis in milk of the commercial Lc. lactis subsp. cremoris starter strains in this study did not always correlate with lactocepin specificity and AcmA degradation. The distribution of autolysins within the cell envelope of Lc. lactis subsp. cremoris starter strains and derivatives harvested during growth in milk was compared by zymogram analysis. AcmA was found associated with cell membranes as well as cell walls and some cleavage of AcmA occurred independently of lactocepin activity. An AcmA product intermediate in size between precursor (46 kDa) and mature (41 kDa) forms of AcmA was clearly visible on zymograms, even in the absence of lactocepin I activity. These results show that autolysis of commercial Lc. lactis subsp. cremoris starter strains is not primarily determined by AcmA activity in relation to lactocepin specificity and that proteolytic cleavage of AcmA in vivo is not fully defined.

scholarly journals Alkaloid-Rich Crude Extracts, Fractions and Piperamide Alkaloids of Piper guineense Possess Promising Antibacterial Effects

Antibiotics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 98 ◽  
Author(s):  
Eunice Mgbeahuruike ◽  
Pia Fyhrquist ◽  
Heikki Vuorela ◽  
Riitta Julkunen-Tiitto ◽  
Yvonne Holm
Keyword(s):  
Antibacterial Activity ◽  
Pathogenic Bacteria ◽  
Bacterial Resistance ◽  
Hot Water ◽  
Bacterial Strains ◽  
Inhibitory Effects ◽  
Piper Guineense ◽  
E Coli ◽  
Growth Inhibitory ◽  
Derivatives Of

Piper guineense is a food and medicinal plant commonly used to treat infectious diseases in West-African traditional medicine. In a bid to identify new antibacterial compounds due to bacterial resistance to antibiotics, twelve extracts of P. guineense fruits and leaves, obtained by sequential extraction, as well as the piperine and piperlongumine commercial compounds were evaluated for antibacterial activity against human pathogenic bacteria. HPLC-DAD and UHPLC/Q-TOF MS analysis were conducted to characterize and identify the compounds present in the extracts with promising antibacterial activity. The extracts, with the exception of the hot water decoctions and macerations, contained piperamide alkaloids as their main constituents. Piperine, dihydropiperine, piperylin, dihydropiperylin or piperlonguminine, dihydropiperlonguminine, wisanine, dihydrowisanine and derivatives of piperine and piperidine were identified in a hexane extract of the leaf. In addition, some new piperamide alkaloids were identified, such as a piperine and a piperidine alkaloid derivative and two unknown piperamide alkaloids. To the best of our knowledge, there are no piperamides reported in the literature with similar UVλ absorption maxima and masses. A piperamide alkaloid-rich hexane leaf extract recorded the lowest MIC of 19 µg/mL against Sarcina sp. and gave promising growth inhibitory effects against S. aureus and E. aerogenes as well, inhibiting the growth of both bacteria with a MIC of 78 µg/mL. Moreover, this is the first report of the antibacterial activity of P. guineense extracts against Sarcina sp. and E. aerogenes. Marked growth inhibition was also obtained for chloroform extracts of the leaves and fruits against P. aeruginosa with a MIC value of 78 µg/mL. Piperine and piperlongumine were active against E. aerogenes, S. aureus, E. coli, S. enterica, P. mirabilis and B. cereus with MIC values ranging from 39–1250 µg/mL. Notably, the water extracts, which were almost devoid of piperamide alkaloids, were not active against the bacterial strains. Our results demonstrate that P. guineense contains antibacterial alkaloids that could be relevant for the discovery of new natural antibiotics.

scholarly journals Effect of pasteurization and starter cultures on physicochemical and microbiological properties of costeño cheese

2016 ◽  
Vol 69 (2) ◽  
pp. 8007-8014 ◽  
Author(s):  
José G. Serpa ◽  
Tulia I. Pérez ◽  
Elvis J. Hernández
Keyword(s):  
Lactococcus Lactis ◽  
Control Sample ◽  
Raw Milk ◽  
Starter Cultures ◽  
Sensorial Analysis ◽  
Pasteurized Milk ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
And Control ◽  
Microbiological Properties

The effect of pasteurization and starter cultures on physicochemical, microbiological and sensorial characteristics of costeño cheese was determined. A completely randomized design was conducted, three treatments (T) and three replicates: Treatment 1 (T1): cheese manufactured with pasteurized milk without starter cultures, Treatment 2 (T2): cheese manufactured with pasteurized milk with Lactococcus lactis and Lactococcus cremoris (1:1) and Treatment 3 (T3): cheese manufactured with pasteurized milk with Lactococcus lactis, Lactococcus cremoris and Streptococcus thermophillus(0.5:0.5:1). Treatments were compared to a control sample that was prepared with raw milk without starter cultures. Concentration of 1.5% (v/v) of culture was used in relation to the amount of used milk in each treatment. Moisture content was higher in all treatments compared to the control and protein and fat content were significantly lower. Acidity was significantly higher in samples from T2 y T3 compared to T1 and control, due to the metabolism of starter cultures. Total coliforms, yeast and mold counts showed a significant reduction due to pasteurization process in all treatments. Regarding sensorial analysis, hedonic test showed a greater preference in cheese manufactured with T2 (P<0.05). There were no significant preferences between T1, T3 and control. Additionally, yield was significantly higher with T1 (22%) and T3 (23%) compared to control.

scholarly journals Evaluation of antimicrobial effect of Commercial Norbixin pigment (Bixa orellana L.) against pathogenic bacteria and food spoilage in vitro

2022 ◽  
Vol 18 (119) ◽  
pp. 133-142
Author(s):  
Ahmad Nasrollahzadeh ◽  
MAHMOUD REZAZAD ◽  
ALMASI almasi ◽  
MEHRAN moradi ◽  
seyed mohamad ali ebrahimzade mousavi ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Antimicrobial Effect ◽  
Bixa Orellana ◽  
Food Spoilage

Diversity in NaCl tolerance of Lactococcus lactis strains from dl-starter cultures for production of semi-hard cheeses

2020 ◽  
Vol 105 ◽  
pp. 104673 ◽  
Author(s):  
Lise Søndergaard Kristensen ◽  
Henrik Siegumfeldt ◽  
Nadja Larsen ◽  
Lene Jespersen
Keyword(s):  
Lactococcus Lactis ◽  
Starter Cultures ◽  
Nacl Tolerance

scholarly journals Activation of the Diacetyl/Acetoin Pathway in Lactococcus lactis subsp. lactis bv. diacetylactis CRL264 by Acidic Growth

2008 ◽  
Vol 74 (7) ◽  
pp. 1988-1996 ◽  
Author(s):  
Nieves García-Quintáns ◽  
Guillermo Repizo ◽  
Mauricio Martín ◽  
Christian Magni ◽  
Paloma López
Keyword(s):  
Lactococcus Lactis ◽  
Biosynthetic Pathway ◽  
Growth Conditions ◽  
Aroma Compounds ◽  
Starter Cultures ◽  
Pcr Analysis ◽  
Transcriptional Level ◽  
Ph Homeostasis ◽  
Acid Growth ◽  
The Impact

ABSTRACT Lactococcus lactis subsp. lactis bv. diacetylactis strains are aroma-producing organisms used in starter cultures for the elaboration of dairy products. This species is essentially a fermentative microorganism, which cometabolizes glucose and citrate to yield aroma compounds through the diacetyl/acetoin biosynthetic pathway. Our previous results have shown that under acidic growth Lactococcus bv. diacetylactis CRL264 expresses coordinately the genes responsible for citrate transport and its conversion into pyruvate. In the present work the impact of acidic growth on glucose, citrate, and pyruvate metabolism of Lactococcus bv. diacetylactis CRL264 has been investigated by proteomic analysis. The results indicated that acid growth triggers the conversion of citrate, but not glucose, into α-acetolactate via pyruvate. Moreover, they showed that low pH has no influence on levels of lactate dehydrogenase and pyruvate dehydrogenase. Therefore, the influence of external pH on regulation of the diacetyl/acetoin biosynthetic pathway in Lactococcus bv. diacetylactis CRL264 has been analyzed at the transcriptional level. Expression of the als, aldB, aldC, and butBA genes encoding the enzymes involved in conversion of pyruvate into aroma compounds has been investigated by primer extension, reverse transcription-PCR analysis, and transcriptional fusions. The results support that this biosynthetic pathway is induced at the transcriptional level by acidic growth conditions, presumably contributing to lactococcal pH homeostasis by synthesis of neutral compounds and by decreasing levels of pyruvate.

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