Clostridium sporogenes and Clostridium tepidium strains were detected in traditional Kashar cheese samples with late blowing characteristics.To control Clostridium spp.,in Kashar cheese,dairy originated Lactic Acid Ba...Clostridium sporogenes and Clostridium tepidium strains were detected in traditional Kashar cheese samples with late blowing characteristics.To control Clostridium spp.,in Kashar cheese,dairy originated Lactic Acid Bacteria(LAB)strains were tested under in vitro conditions and during Kashar production.Two strains,Lactiplantibacillus plantarum and Lactococcus lactis subsp.lactis demonstrated anticlostridial activity in vitro and the co-inoculum of these two strains(107 cfu g^(-1))were tested during the challenge test on Kashar cheese production in which a contamination ratio of 10^(4) cfu g^(-1) with spores of Cl.sporogenes were applied.Kashar samples were stored at 4℃ and 25℃ during 40 days of storage period and microbiological and physicochemical properties of Kashar samples were determined during this period.A decrement of nearly 1 log cfu g^(-1) in Cl.sporogenes numbers was observed in Kashar samples produced with co-inoculum of Lb.plantarum and L.lactis subsp.lactis stored at 4℃ but this was not the case for the Kashar samples stored at 25℃.This study revealed the potential of distinct LAB strains to control Cl.sporogenes spores in semi-hard cheese samples as biocontrol agents at 4℃ storage.展开更多
Objective To construct four recombinant Lactococcus lactis strains exhibiting high β-galactosidase activity in fusion or non-fusion ways, and to study the influence factors for their protein expression and secretion....Objective To construct four recombinant Lactococcus lactis strains exhibiting high β-galactosidase activity in fusion or non-fusion ways, and to study the influence factors for their protein expression and secretion. Methods The gene fragments encoding β-galactosidase from two strains of Loctobacillus bulgaricus, wch9901 isolated from yogurt and 1.1480 purchased from the Chinese Academy of Sciences, were amplified and inserted into lactococcal expression vector pMG36e. For fusion expression, the open reading frame of the β-galactosidase gene was amplified, while for non-fusion expression, the open reading frame of the β-galactosidase gene was amplified with its native Shine-Dalgarno sequence upstream. The start codon of the β-galactosidase gene partially overlapped with the stop codon of vector origin open reading frame. Then, the recombinant plasmids were transformed into Escherichia coli DH5α and Lactococcus lactis subsp, lactis MG1363 and confirmed by determining β-galactosidase activities. Results The non-fusion expression plasmids showed a significantly higher β-galactosidase activity in transformed strains than the fusion expression plasmids. The highest enzyme activity was observed in Lactococcus lactis transformed with the non-fusion expression plasmids which were inserted into the β-galactosidase gene from Lactobacillus bulgaricus wch9901. The β-galactosidase activity was 2.75 times as high as that of the native counterpart. In addition, β-galactosidase expressed by recombinant plasmids in Lactococcus lactis could be secreted into the culture medium. The highest secretion rate （27.1%） was observed when the culture medium contained 20 g/L of lactose. Conclusion Different properties of the native bacteria may have some effects on the protein expression of recombinant plasmids. Non-fusion expression shows a higher enzyme activity in host bacteria. There may be a host-related weak secretion signal peptide gene within the structure gene of Lb. bulgaricus β-galactosidase, and its translation product may introduce the enzyme secretion out of cells in special hosts.展开更多
To evaluate the specific immune responses induced by recombinant Lactococcus lactis（L.lactis） which expresses porcine epidemic diarrhea virus（PEDV） S1 protein through oral administration,the spike gene fragment of...To evaluate the specific immune responses induced by recombinant Lactococcus lactis（L.lactis） which expresses porcine epidemic diarrhea virus（PEDV） S1 protein through oral administration,the spike gene fragment of PEDV was amplified from PEDV SDLY strain to construct p MG36 e-S1 recombinant plasmid.The recombinant plasmid was then electro-transferred into competent cells of L.lactis MG1363,to prepare the recombinant L.lactis expressing S1 protein of PEDV.The expression of target protein was identified by SDS-PAGE and Western-blot.New Zealand white rabbits were orally administered with the recombinant strain;the antibody titer in intestinal mucosa and serum was detected by neutralizing test;and the specific Ig G in serum was evaluated by indirect ELISA.The results showed that the recombinant L.lactis could effectively induce high level of Ig G in serum and high level of mucosal immune antibody.The recombinant L.lactis is qualified to be a potential oral vaccine because it could successfully stimulate both humoral and mucosal immune responses against PEDV.展开更多
In this study, a plasmid was integrated into nisP, creating the first defined mutation in a nisin biosynthetic gene. The mutant strain secreted fully modified nisin with the N-terminal leader still attached.The presen...In this study, a plasmid was integrated into nisP, creating the first defined mutation in a nisin biosynthetic gene. The mutant strain secreted fully modified nisin with the N-terminal leader still attached.The presence of the leader was confirmed by N-terminal sequencing of the purified precursor. The dehydration and lanthionine formation of the precursor were already completed as active nisin could be formed by cleaving the leader from the inactive precursor by a trypsin treatment or by incubation with wild type cells. Nisin immunity of the NisP mutant strain was lowered to about 10% of the wild type immunity. The results show that NisP is needed for precursor processing and for development of high immunity of nisin.展开更多
The influence of relative humidity (RH) on quasistatic current-voltage (I-V) characteristics of Bifidobacterium animalis subsp. lactis BB-12 thin layers was studied for the first time. The value of electrical conducti...The influence of relative humidity (RH) on quasistatic current-voltage (I-V) characteristics of Bifidobacterium animalis subsp. lactis BB-12 thin layers was studied for the first time. The value of electrical conductivity in 75% RH was found to be in the order of 10-7 (ohm·cm)-1, which was 106 orders of magnitude higher than that observed in dry atmosphere. It was concluded that RH played a key role in hysteresis behavior of the measured (I-V) characteristics. FTIR measurements showed that under water moisture environment, the associated bonds between amine and carboxyl group were greatly strengthened that was the source of free charge carries after ionization. The surface charge of Bifidobacterium animalis subsp. lactis BB-12 was found to be negative by zeta potential measurements, claiming that electrons were the charge carriers.展开更多
Bovine mastitis affects the udder health and thus causing significant economic losses. Probiotic products based on the use of lactic acid bacteria (LAB) to limit pathogens multiplication and pre-infection risks can be...Bovine mastitis affects the udder health and thus causing significant economic losses. Probiotic products based on the use of lactic acid bacteria (LAB) to limit pathogens multiplication and pre-infection risks can be an interesting alternative to post infection allopathic treatment with antibiotics. Lactococcus lactis is one of the most important bacteria used in dairy technology. In this work, a total of 21 Lactococcus lactis subsp. Lactis strains, 20 from goat milk whey and one strain from cow milk were used to evaluate their antibacterial activity against four pathogenic germs responsible for mastitis: Escherichia coli, Staphylococcus aureus, Streptococcus uberis and Streptococcus agalactiae. The nisin-producing cow milk strain was active against St. uberis and Str. Agalactiae using the well diffusion method. For the strains isolated from goat milk whey, no antimicrobial effect was observed against these pathogens. However, a different approach based on the growth of pathogenic bacteria interacting with the Lactococcus lactis strains in a minimum medium was used to study the barrier effect of LAB. The Lactococcus lactis strains S1 and S2 from goat milk whey depleted the growth of Sa. aureus, St. uberis and E. coli during 8 h and stopped the development of St. agalactiae.展开更多
Objective: A community-based intervention study was conducted to examine the effect of consumption of JCM 5805 yogurt on influenza incidence rates and the cumulative incidence rates among schoolchildren in Iwate Prefe...Objective: A community-based intervention study was conducted to examine the effect of consumption of JCM 5805 yogurt on influenza incidence rates and the cumulative incidence rates among schoolchildren in Iwate Prefecture, Japan. Methods: Schoolchildren and their parents in Shizukuishi town were told of the purpose, frequency and duration of JCM 5805 yogurt administration. The number of elementary schoolchildren in Shizukuishi town was 780 while that of junior high school students in Shizukuishi town numbered 475. The number of elementary schoolchildren in neighboring town A was 208 and that of junior high school students in town A was 121. JCM 5805 yogurt was delivered three times a week to all elementary schools and junior high schools in Shizukuishi town from January 16 through March 18, 2015. The incidence rate was calculated every week as the maximum case number divided by the number of schoolchildren in each school. The cumulative incidence rate was calculated as the total case number during the period when JCM 5805 yogurt was delivered divided by the number of schoolchildren in each school. Results: JCM 5805 yogurt intake was associated with a two-thirds reduction in influenza incidence rates in Shizukuishi town schoolchildren compared with those of town A. Furthermore, the cumulative incidence rates of the elementary school and combined data from the elementary school and junior high school were significantly lower than those of neighbor town A. Conclusion: JCM 5805 yogurt intake reduced both the incidence rates and cumulative incidence rates of influenza.展开更多
Background/Aims: Administration of a lactic acid bacterial strain, Lactococcus lactis subsp. lactis JCM 5805 (LC-Plasma), is reported to prevent viral infection via activation of plasmacytoid dendritic cells in mouse ...Background/Aims: Administration of a lactic acid bacterial strain, Lactococcus lactis subsp. lactis JCM 5805 (LC-Plasma), is reported to prevent viral infection via activation of plasmacytoid dendritic cells in mouse and human studies. As it is assumed that LC-Plasma is taken in excess when it is commercially provided as a supplement, we conducted a trial using capsules to give 250 mg LC-Plasma (5 times the effective anti-viral dose) every day for four weeks to healthy volunteers to investigate the safety of excessive intake of LC-Plasma. Trial Design: A randomized, double-blind, placebo-controlled, parallel-group trial was conducted. Methods: Forty healthy subjects were randomly assigned to the LC-Plasma group (daily intake of five capsules containing 50 mg heat-killed LC-Plasma cells per capsule) or the placebo group (daily intake of five placebo capsules with no LC-Plasma). Physical, hematological, biochemical and urinary examinations and medical interviews were used to evaluate safety. Results: No abnormal differences were observed after excessive intake of LC-Plasma capsules when compared to the intake of placebo capsules. Conclusions: There are no safety concerns associated with the excessive intake of heat-killed LC-Plasma capsules.展开更多
Oxidative stress has been strongly related with Parkinson disease (PD) and Alzheimer disease pathogenesis. We determined the effects of Lactococcus lactis (LAL) supplementation on the generated loss-of-function mutant...Oxidative stress has been strongly related with Parkinson disease (PD) and Alzheimer disease pathogenesis. We determined the effects of Lactococcus lactis (LAL) supplementation on the generated loss-of-function mutants of PINK1 B9, an AR-JP-linked gene and Aβ42 induced phenotypes in a Drosophila melanogaster model of PD/AD. Enhanced mutant PINK1 B9 and Aβ42 expression in D. melanogaster dopaminergic (DA) neurons can curtail lifespan, flight muscle accompanied by locomotive defects and we have observed longevity methods to assay the effects of LAL on D. melanogaster survival. Furthermore, flies expressing mutant PINK1 B9 and Aβ42 in their brain fed LAL had up to the two weeks, or 25%, greater median lifespan than those fed a standard sucrose diet. In addition, LAL improved mutant PINK1 B9 and Aβ42-induced flight impairments in the Drosophila wing. Our microscopy analyses revealed that individuals fed LAL had improved atypical ommatidia as well as an increased thirteen percentage of flight ability than those fed a control diet. We propose that LAL, rich in naturally occurring probiotics and antioxidants, promotes the survival of neurons in brain and wing muscle tissues with increased levels of mutant PINK1 B9 and Aβ42 via a protective cell survival mechanism.展开更多
Raw goat milk cheeses are known for their natural microflora linked to many biodiversity factors such as the use of raw milk. That microflora serves probiotic attribution conferring a beneficial health impact on the c...Raw goat milk cheeses are known for their natural microflora linked to many biodiversity factors such as the use of raw milk. That microflora serves probiotic attribution conferring a beneficial health impact on the consumer. Darfiyeh is an artisanal raw goat milk cheese manufactured traditionally in Northern Lebanese Mountains. To emphasize its clinical significance in both digestive and immune system, and to provide health remunerations to the consumer, the cheese microbiota will be investigated. To serve that purpose, the presence of the two potent probiotic Lactic Acid Bacteria (LAB): Lactococcus lactis subsp. lactis and Lactobacillus plantarum will be investigated. For bacterial identification, selection and isolation: culture-dependent techniques that imply the use of laboratory media will be implemented, and culture independent techniques: Polymerase Chain Reaction (PCR) will be applied for further validation. Both bacteria were further verified as Lactococcus lactis subsp. lactis and Lactobacillus plantarum by implementing specie-specific primers for the qualitative PCR.展开更多
Objective:To determine the inhibition mechanisms of secretome protein extracted from Paenibacillus polymyxa Kp10(Kp10)and Lactococcus lactis Gh1(Gh1)against methicillin-resistant Staphylococcus aureus(MRSA)and vancomy...Objective:To determine the inhibition mechanisms of secretome protein extracted from Paenibacillus polymyxa Kp10(Kp10)and Lactococcus lactis Gh1(Gh1)against methicillin-resistant Staphylococcus aureus(MRSA)and vancomycin-resistant Enterococcus(VRE).Methods:The sensitivity and viability of MRSA and VRE treated with secretome proteins of Kp10 and Gh1 were determined using minimal inhibitory concentration,minimum bactericidal concentration,and time-to-kill assays.The morphological changes were observed using scanning electron microscopy and transmission electron microscopy.To elucidate the antimicrobial mechanism of secretome protein of Kp10 and Gh1 against MRSA and VRE,2D gel proteomic analysis using liquid chromatography-mass spectrometry was run by comparing upregulated and downregulated proteins,and the proton motive force study including the efflux of ATP,pH gradient,and the membrane potential study were conducted.Results:MRSA and VRE were sensitive to Kp10 and Gh1 secretome protein extracts and displayed apparent morphological and internal composition changes.Several proteins associated with cellular component functions were either downregulated or upregulated in treated MRSA and VRE by changing the membrane potential gradient.Conclusions:Kp10 and Gh1 secretome proteins reduce the growth of VRE and MRSA by damaging the cell membrane.Cell division,cell wall biosynthesis,and protein synthesis are involved in the inhibition mechanism.展开更多
基金Fatmanur Demirbas¸was supported by Turkish Council of Higher Education with 100/2000 PhD programme and by TUB˙ITAK with 2211-C programme.
文摘Clostridium sporogenes and Clostridium tepidium strains were detected in traditional Kashar cheese samples with late blowing characteristics.To control Clostridium spp.,in Kashar cheese,dairy originated Lactic Acid Bacteria(LAB)strains were tested under in vitro conditions and during Kashar production.Two strains,Lactiplantibacillus plantarum and Lactococcus lactis subsp.lactis demonstrated anticlostridial activity in vitro and the co-inoculum of these two strains(107 cfu g^(-1))were tested during the challenge test on Kashar cheese production in which a contamination ratio of 10^(4) cfu g^(-1) with spores of Cl.sporogenes were applied.Kashar samples were stored at 4℃ and 25℃ during 40 days of storage period and microbiological and physicochemical properties of Kashar samples were determined during this period.A decrement of nearly 1 log cfu g^(-1) in Cl.sporogenes numbers was observed in Kashar samples produced with co-inoculum of Lb.plantarum and L.lactis subsp.lactis stored at 4℃ but this was not the case for the Kashar samples stored at 25℃.This study revealed the potential of distinct LAB strains to control Cl.sporogenes spores in semi-hard cheese samples as biocontrol agents at 4℃ storage.
基金a scientific research grant from Health Bureau of Sichuan Province (No. F0201)
文摘Objective To construct four recombinant Lactococcus lactis strains exhibiting high β-galactosidase activity in fusion or non-fusion ways, and to study the influence factors for their protein expression and secretion. Methods The gene fragments encoding β-galactosidase from two strains of Loctobacillus bulgaricus, wch9901 isolated from yogurt and 1.1480 purchased from the Chinese Academy of Sciences, were amplified and inserted into lactococcal expression vector pMG36e. For fusion expression, the open reading frame of the β-galactosidase gene was amplified, while for non-fusion expression, the open reading frame of the β-galactosidase gene was amplified with its native Shine-Dalgarno sequence upstream. The start codon of the β-galactosidase gene partially overlapped with the stop codon of vector origin open reading frame. Then, the recombinant plasmids were transformed into Escherichia coli DH5α and Lactococcus lactis subsp, lactis MG1363 and confirmed by determining β-galactosidase activities. Results The non-fusion expression plasmids showed a significantly higher β-galactosidase activity in transformed strains than the fusion expression plasmids. The highest enzyme activity was observed in Lactococcus lactis transformed with the non-fusion expression plasmids which were inserted into the β-galactosidase gene from Lactobacillus bulgaricus wch9901. The β-galactosidase activity was 2.75 times as high as that of the native counterpart. In addition, β-galactosidase expressed by recombinant plasmids in Lactococcus lactis could be secreted into the culture medium. The highest secretion rate （27.1%） was observed when the culture medium contained 20 g/L of lactose. Conclusion Different properties of the native bacteria may have some effects on the protein expression of recombinant plasmids. Non-fusion expression shows a higher enzyme activity in host bacteria. There may be a host-related weak secretion signal peptide gene within the structure gene of Lb. bulgaricus β-galactosidase, and its translation product may introduce the enzyme secretion out of cells in special hosts.
基金Supported by Priority Academic Talent Team Cultivation Program of Shandong Colleges and Universities and Agricultural Industry Research System of Shandong Province(SDAIT-06-022-08)People’s Livelihood Science and Technology Program of Qingdao City(16-6-2-42-nsh)
文摘To evaluate the specific immune responses induced by recombinant Lactococcus lactis（L.lactis） which expresses porcine epidemic diarrhea virus（PEDV） S1 protein through oral administration,the spike gene fragment of PEDV was amplified from PEDV SDLY strain to construct p MG36 e-S1 recombinant plasmid.The recombinant plasmid was then electro-transferred into competent cells of L.lactis MG1363,to prepare the recombinant L.lactis expressing S1 protein of PEDV.The expression of target protein was identified by SDS-PAGE and Western-blot.New Zealand white rabbits were orally administered with the recombinant strain;the antibody titer in intestinal mucosa and serum was detected by neutralizing test;and the specific Ig G in serum was evaluated by indirect ELISA.The results showed that the recombinant L.lactis could effectively induce high level of Ig G in serum and high level of mucosal immune antibody.The recombinant L.lactis is qualified to be a potential oral vaccine because it could successfully stimulate both humoral and mucosal immune responses against PEDV.
文摘In this study, a plasmid was integrated into nisP, creating the first defined mutation in a nisin biosynthetic gene. The mutant strain secreted fully modified nisin with the N-terminal leader still attached.The presence of the leader was confirmed by N-terminal sequencing of the purified precursor. The dehydration and lanthionine formation of the precursor were already completed as active nisin could be formed by cleaving the leader from the inactive precursor by a trypsin treatment or by incubation with wild type cells. Nisin immunity of the NisP mutant strain was lowered to about 10% of the wild type immunity. The results show that NisP is needed for precursor processing and for development of high immunity of nisin.
文摘The influence of relative humidity (RH) on quasistatic current-voltage (I-V) characteristics of Bifidobacterium animalis subsp. lactis BB-12 thin layers was studied for the first time. The value of electrical conductivity in 75% RH was found to be in the order of 10-7 (ohm·cm)-1, which was 106 orders of magnitude higher than that observed in dry atmosphere. It was concluded that RH played a key role in hysteresis behavior of the measured (I-V) characteristics. FTIR measurements showed that under water moisture environment, the associated bonds between amine and carboxyl group were greatly strengthened that was the source of free charge carries after ionization. The surface charge of Bifidobacterium animalis subsp. lactis BB-12 was found to be negative by zeta potential measurements, claiming that electrons were the charge carriers.
文摘Bovine mastitis affects the udder health and thus causing significant economic losses. Probiotic products based on the use of lactic acid bacteria (LAB) to limit pathogens multiplication and pre-infection risks can be an interesting alternative to post infection allopathic treatment with antibiotics. Lactococcus lactis is one of the most important bacteria used in dairy technology. In this work, a total of 21 Lactococcus lactis subsp. Lactis strains, 20 from goat milk whey and one strain from cow milk were used to evaluate their antibacterial activity against four pathogenic germs responsible for mastitis: Escherichia coli, Staphylococcus aureus, Streptococcus uberis and Streptococcus agalactiae. The nisin-producing cow milk strain was active against St. uberis and Str. Agalactiae using the well diffusion method. For the strains isolated from goat milk whey, no antimicrobial effect was observed against these pathogens. However, a different approach based on the growth of pathogenic bacteria interacting with the Lactococcus lactis strains in a minimum medium was used to study the barrier effect of LAB. The Lactococcus lactis strains S1 and S2 from goat milk whey depleted the growth of Sa. aureus, St. uberis and E. coli during 8 h and stopped the development of St. agalactiae.
文摘Objective: A community-based intervention study was conducted to examine the effect of consumption of JCM 5805 yogurt on influenza incidence rates and the cumulative incidence rates among schoolchildren in Iwate Prefecture, Japan. Methods: Schoolchildren and their parents in Shizukuishi town were told of the purpose, frequency and duration of JCM 5805 yogurt administration. The number of elementary schoolchildren in Shizukuishi town was 780 while that of junior high school students in Shizukuishi town numbered 475. The number of elementary schoolchildren in neighboring town A was 208 and that of junior high school students in town A was 121. JCM 5805 yogurt was delivered three times a week to all elementary schools and junior high schools in Shizukuishi town from January 16 through March 18, 2015. The incidence rate was calculated every week as the maximum case number divided by the number of schoolchildren in each school. The cumulative incidence rate was calculated as the total case number during the period when JCM 5805 yogurt was delivered divided by the number of schoolchildren in each school. Results: JCM 5805 yogurt intake was associated with a two-thirds reduction in influenza incidence rates in Shizukuishi town schoolchildren compared with those of town A. Furthermore, the cumulative incidence rates of the elementary school and combined data from the elementary school and junior high school were significantly lower than those of neighbor town A. Conclusion: JCM 5805 yogurt intake reduced both the incidence rates and cumulative incidence rates of influenza.
文摘Background/Aims: Administration of a lactic acid bacterial strain, Lactococcus lactis subsp. lactis JCM 5805 (LC-Plasma), is reported to prevent viral infection via activation of plasmacytoid dendritic cells in mouse and human studies. As it is assumed that LC-Plasma is taken in excess when it is commercially provided as a supplement, we conducted a trial using capsules to give 250 mg LC-Plasma (5 times the effective anti-viral dose) every day for four weeks to healthy volunteers to investigate the safety of excessive intake of LC-Plasma. Trial Design: A randomized, double-blind, placebo-controlled, parallel-group trial was conducted. Methods: Forty healthy subjects were randomly assigned to the LC-Plasma group (daily intake of five capsules containing 50 mg heat-killed LC-Plasma cells per capsule) or the placebo group (daily intake of five placebo capsules with no LC-Plasma). Physical, hematological, biochemical and urinary examinations and medical interviews were used to evaluate safety. Results: No abnormal differences were observed after excessive intake of LC-Plasma capsules when compared to the intake of placebo capsules. Conclusions: There are no safety concerns associated with the excessive intake of heat-killed LC-Plasma capsules.
文摘Oxidative stress has been strongly related with Parkinson disease (PD) and Alzheimer disease pathogenesis. We determined the effects of Lactococcus lactis (LAL) supplementation on the generated loss-of-function mutants of PINK1 B9, an AR-JP-linked gene and Aβ42 induced phenotypes in a Drosophila melanogaster model of PD/AD. Enhanced mutant PINK1 B9 and Aβ42 expression in D. melanogaster dopaminergic (DA) neurons can curtail lifespan, flight muscle accompanied by locomotive defects and we have observed longevity methods to assay the effects of LAL on D. melanogaster survival. Furthermore, flies expressing mutant PINK1 B9 and Aβ42 in their brain fed LAL had up to the two weeks, or 25%, greater median lifespan than those fed a standard sucrose diet. In addition, LAL improved mutant PINK1 B9 and Aβ42-induced flight impairments in the Drosophila wing. Our microscopy analyses revealed that individuals fed LAL had improved atypical ommatidia as well as an increased thirteen percentage of flight ability than those fed a control diet. We propose that LAL, rich in naturally occurring probiotics and antioxidants, promotes the survival of neurons in brain and wing muscle tissues with increased levels of mutant PINK1 B9 and Aβ42 via a protective cell survival mechanism.
文摘Raw goat milk cheeses are known for their natural microflora linked to many biodiversity factors such as the use of raw milk. That microflora serves probiotic attribution conferring a beneficial health impact on the consumer. Darfiyeh is an artisanal raw goat milk cheese manufactured traditionally in Northern Lebanese Mountains. To emphasize its clinical significance in both digestive and immune system, and to provide health remunerations to the consumer, the cheese microbiota will be investigated. To serve that purpose, the presence of the two potent probiotic Lactic Acid Bacteria (LAB): Lactococcus lactis subsp. lactis and Lactobacillus plantarum will be investigated. For bacterial identification, selection and isolation: culture-dependent techniques that imply the use of laboratory media will be implemented, and culture independent techniques: Polymerase Chain Reaction (PCR) will be applied for further validation. Both bacteria were further verified as Lactococcus lactis subsp. lactis and Lactobacillus plantarum by implementing specie-specific primers for the qualitative PCR.
基金supported by the funds of Ministry of Higher Education,Malaysia and Universiti Putra Malaysia through Fundamental Research Grant Scheme (FRGS/1/2017/SKK11/UPM/01/1) and Putra Grant (GP/2017/9571800)
文摘Objective:To determine the inhibition mechanisms of secretome protein extracted from Paenibacillus polymyxa Kp10(Kp10)and Lactococcus lactis Gh1(Gh1)against methicillin-resistant Staphylococcus aureus(MRSA)and vancomycin-resistant Enterococcus(VRE).Methods:The sensitivity and viability of MRSA and VRE treated with secretome proteins of Kp10 and Gh1 were determined using minimal inhibitory concentration,minimum bactericidal concentration,and time-to-kill assays.The morphological changes were observed using scanning electron microscopy and transmission electron microscopy.To elucidate the antimicrobial mechanism of secretome protein of Kp10 and Gh1 against MRSA and VRE,2D gel proteomic analysis using liquid chromatography-mass spectrometry was run by comparing upregulated and downregulated proteins,and the proton motive force study including the efflux of ATP,pH gradient,and the membrane potential study were conducted.Results:MRSA and VRE were sensitive to Kp10 and Gh1 secretome protein extracts and displayed apparent morphological and internal composition changes.Several proteins associated with cellular component functions were either downregulated or upregulated in treated MRSA and VRE by changing the membrane potential gradient.Conclusions:Kp10 and Gh1 secretome proteins reduce the growth of VRE and MRSA by damaging the cell membrane.Cell division,cell wall biosynthesis,and protein synthesis are involved in the inhibition mechanism.
