1
|
Wörmann ME, Pech J, Reich F, Tenhagen BA, Wichmann-Schauer H, Lienen T. Growth of methicillin-resistant Staphylococcus aureus during raw milk soft cheese-production and the inhibitory effect of starter cultures. Food Microbiol 2024; 119:104451. [PMID: 38225052 DOI: 10.1016/j.fm.2023.104451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 01/17/2024]
Abstract
The consumption of raw milk or raw milk products might be a potential risk factor for the transmission of methicillin-resistant Staphylococcus aureus (MRSA). Therefore, we studied MRSA growth during raw milk soft cheese-production. Furthermore, we investigated the inhibitory effect of four starter cultures (Lactococcus lactis, Lacticaseibacillus rhamnosus, Lactiplantibacillus plantarum, Lactobacillus helveticus) on the growth of MRSA in a spot-agar-assay and in raw milk co-culture following a cheesemaking temperature profile. During the initial phases of raw milk cheese-production, MRSA counts increased by 2 log units. In the ripening phase, MRSA counts only dropped slightly and remained high up to the end of the storage. Comparable MRSA counts were found in the rind and core and strain-specific differences in survival were observed. In the spot-agar-assay, all four starter cultures showed strong or intermediate inhibition of MRSA growth. In contrast, in raw milk, only Lactococcus lactis strongly inhibited MRSA, whereas all other starter cultures only had minor inhibitory effects on MRSA growth. Our results indicate that MRSA follow a similar growth pattern as described for other S. aureus during raw milk soft cheese-production and illustrate the potential use of appropriate starter cultures to inhibit MRSA growth during the production of raw milk cheese.
Collapse
Affiliation(s)
- M E Wörmann
- German Federal Institute for Risk Assessment (BfR), Department Biological Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany.
| | - J Pech
- German Federal Institute for Risk Assessment (BfR), Department Biological Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - F Reich
- German Federal Institute for Risk Assessment (BfR), Department Biological Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - B-A Tenhagen
- German Federal Institute for Risk Assessment (BfR), Department Biological Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - H Wichmann-Schauer
- German Federal Institute for Risk Assessment (BfR), Department Biological Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - T Lienen
- German Federal Institute for Risk Assessment (BfR), Department Biological Safety, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany.
| |
Collapse
|
2
|
Neidhöfer C, Rathore K, Parčina M, Sieber MA. ESKAPEE Pathogen Biofilm Control on Surfaces with Probiotic Lactobacillaceae and Bacillus species. Antibiotics (Basel) 2023; 12:871. [PMID: 37237774 PMCID: PMC10215598 DOI: 10.3390/antibiotics12050871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/21/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
Combatting the rapidly growing threat of antimicrobial resistance and reducing prevalence and transmission of ESKAPEE pathogens in healthcare settings requires innovative strategies, one of which is displacing these pathogens using beneficial microorganisms. Our review comprehensively examines the evidence of probiotic bacteria displacing ESKAPEE pathogens, with a focus on inanimate surfaces. A systematic search was conducted using the PubMed and Web of Science databases on 21 December 2021, and 143 studies were identified examining the effects of Lactobacillaceae and Bacillus spp. cells and products on the growth, colonization, and survival of ESKAPEE pathogens. While the diversity of study methods limits evidence analysis, results presented by narrative synthesis demonstrate that several species have the potential as cells or their products or supernatants to displace nosocomial infection-causing organisms in a variety of in vitro and in vivo settings. Our review aims to aid the development of new promising approaches to control pathogen biofilms in medical settings by informing researchers and policymakers about the potential of probiotics to combat nosocomial infections. More targeted studies are needed to assess safety and efficacy of different probiotic formulations, followed by large-scale studies to assess utility in infection control and medical practice.
Collapse
Affiliation(s)
- Claudio Neidhöfer
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Kamni Rathore
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
- Institute for Functional Gene Analytics, Bonn-Rhein-Sieg University of Applied Sciences, 53757 Sankt Augustin, Germany
| | - Marijo Parčina
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Martin A. Sieber
- Institute for Functional Gene Analytics, Bonn-Rhein-Sieg University of Applied Sciences, 53757 Sankt Augustin, Germany
| |
Collapse
|
3
|
Nogueira Viçosa G, Vieira Botelho C, Botta C, Bertolino M, Fernandes de Carvalho A, Nero LA, Cocolin L. Impact of co-cultivation with Enterococcus faecalis over growth, enterotoxin production and gene expression of Staphylococcus aureus in broth and fresh cheeses. Int J Food Microbiol 2019; 308:108291. [PMID: 31437692 DOI: 10.1016/j.ijfoodmicro.2019.108291] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 08/04/2019] [Accepted: 08/05/2019] [Indexed: 11/18/2022]
Affiliation(s)
| | | | - Cristian Botta
- Department of Agricultural, Forest and Food Sciences, University of Turin, Grugliasco, Italy
| | - Marta Bertolino
- Department of Agricultural, Forest and Food Sciences, University of Turin, Grugliasco, Italy
| | | | - Luís Augusto Nero
- Departamento de Veterinária, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Luca Cocolin
- Department of Agricultural, Forest and Food Sciences, University of Turin, Grugliasco, Italy.
| |
Collapse
|
4
|
O'Hanlon DE, Come RA, Moench TR. Vaginal pH measured in vivo: lactobacilli determine pH and lactic acid concentration. BMC Microbiol 2019; 19:13. [PMID: 30642259 PMCID: PMC6332693 DOI: 10.1186/s12866-019-1388-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 01/04/2019] [Indexed: 12/04/2022] Open
Abstract
Background Lactic acid (protonated lactate) has broad antimicrobial activity. Vaginal lactobacilli produce lactic acid, and are known to confer protection against reproductive tract infections when they are predominant in the vaginal microbiota. Using novel ex vivo methods, we showed that cervicovaginal fluid (CVF) from women with a predominantly lactobacilli-morphotype microbiota contains significantly more lactic acid than previously thought, sufficient to inactivate reproductive tract pathogens. Here, we measured vaginal pH in vivo in 20 women with a predominantly lactobacilli-morphotype (low Nugent score) microbiota. We also investigated the in vitro production of protons (as hydrogen ions) and lactate by vaginal lactobacilli. Results The average vaginal pH in these women was 3.80 ± 0.20, and the average lactate concentration was 0.79% ± 0.22% w/v, with pH and lactate concentration tightly correlated for each sample. In vitro, lactobacilli cultured from these CVF samples reached an average pH of 3.92 ± 0.22, but the average lactate concentration was only 0.14% ± 0.06% w/v, approximately five-fold less than in the corresponding CVF samples. When the pH of the cultures was raised, lactate and hydrogen ion production resumed, indicating that production of lactate and hydrogen ions by vaginal lactobacilli is limited primarily by their sensitivity to hydrogen ion concentration (low pH) not lactate concentration. Conclusions Some vaginal lactobacilli cultures have a lower limiting pH than others, and limiting pHs in vitro showed good correlation with pHs measured in vivo. The limiting pH of the lactobacilli predominant in a woman’s vaginal microbiota seems critical in determining the concentration of antimicrobial lactic acid protecting her.
Collapse
Affiliation(s)
- Deirdre Elizabeth O'Hanlon
- Institute for Genomic Sciences, University of Maryland School of Medicine, 801 West Baltimore Street, Baltimore, MD, USA.
| | - Richard A Come
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | | |
Collapse
|
5
|
Queiroux C, Bonnet M, Saraoui T, Delpech P, Veisseire P, Rifa E, Moussard C, Gagne G, Delbès C, Bornes S. Dialogue between Staphylococcus aureus SA15 and Lactococcus garvieae strains experiencing oxidative stress. BMC Microbiol 2018; 18:193. [PMID: 30466395 PMCID: PMC6251228 DOI: 10.1186/s12866-018-1340-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 11/14/2018] [Indexed: 02/02/2023] Open
Abstract
Background Staphylococcus aureus is an important foodborne pathogen. Lactococcus garvieae is a lactic acid bacterium found in dairy products; some of its strains are able to inhibit S. aureus growth by producing H2O2. Three strains of L. garvieae from different origins were tested for their ability to inhibit S. aureus SA15 growth. Two conditions were tested, one in which H2O2 was produced (high aeration) and another one in which it was not detected (low aeration). Several S. aureus genes related to stress, H2O2-response and virulence were examined in order to compare their level of expression depending on the inoculated L. garvieae strain. Simultaneous L. garvieae H2O2 metabolism gene expression was followed. Results The results showed that under high aeration condition, L. garvieae strains producing H2O2 (N201 and CL-1183) inhibited S. aureus SA15 growth and impaired its ability to deal with hydrogen peroxide by repressing H2O2-degrading genes. L. garvieae strains induced overexpression of S. aureus stress-response genes while cell division genes and virulence genes were repressed. A catalase treatment partially or completely restored the SA15 growth. In addition, the H2O2 non-producing L. garvieae strain (Lg2) did not cause any growth inhibition. The SA15 stress-response genes were down-regulated and cell division genes expression was not affected. Under low aeration condition, while none of the strains tested exhibited H2O2-production, the 3 L. garvieae strains inhibited S. aureus SA15 growth, but to a lesser extent than under high aeration condition. Conclusion Taken together, these results suggest a L. garvieae strain-specific anti-staphylococcal mechanism and an H2O2 involvement in at least two of the tested L. garvieae strains. Electronic supplementary material The online version of this article (10.1186/s12866-018-1340-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
| | - Muriel Bonnet
- Université Clermont Auvergne, INRA, UMRF, F-15000, Aurillac, France
| | - Taous Saraoui
- Université Clermont Auvergne, INRA, UMRF, F-15000, Aurillac, France
| | - Pierre Delpech
- Université Clermont Auvergne, INRA, UMRF, F-15000, Aurillac, France
| | | | - Etienne Rifa
- Université Clermont Auvergne, INRA, UMRF, F-15000, Aurillac, France
| | - Cécile Moussard
- Université Clermont Auvergne, INRA, UMRF, F-15000, Aurillac, France
| | - Geneviève Gagne
- Université Clermont Auvergne, INRA, UMRF, F-15000, Aurillac, France
| | - Céline Delbès
- Université Clermont Auvergne, INRA, UMRF, F-15000, Aurillac, France.
| | - Stéphanie Bornes
- Université Clermont Auvergne, INRA, UMRF, F-15000, Aurillac, France
| |
Collapse
|
6
|
Mati M, Staruch L. Monitoring of a gluten content in selected meat products from three biggest meat producers in Slovakia. POTRAVINARSTVO 2012. [DOI: 10.5219/167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The work is focused on a monitoring of a gluten content in selected meat products from three biggest and most popular meat producers in Slovakia. Gluten is a type of protein complex which is typical naturally presented component of wheat, barley and rye. Flour from this sources with natural gluten content is also added into the some type of meat products and other foodstuffs for a technological reasons hand in hand with economic reasons. Some of the gluten quantities could be hazardous for sensitive people as celiatics and allergic to gluten. Within the context of this reasons there is a need to control the amounts of this hidden type of gluten inclusive of spice mixes using in a meat production. Monitoring by itself was realized with a use of the sandwich ELISA RIDASCREEN® Fast Gliadin test. ELISA means enzyme linked immunosorbent assay. It is based on a specific reaction among the enzyme and antigen leading to a creation of a complex. This test provides us exact quantitification of a gluten content in this type of food products using a colorimetric reaction of a complex by observing of all fundamentals of this technique. There were analysed 16 meat products and 5 types of spice mixes in total.
Collapse
|
7
|
Staphylococcus aureus virulence expression is impaired by Lactococcus lactis in mixed cultures. Appl Environ Microbiol 2009; 75:4459-72. [PMID: 19429556 DOI: 10.1128/aem.02388-08] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Staphylococcus aureus is responsible for numerous food poisonings due to the production of enterotoxins by strains contaminating foodstuffs, especially dairy products. Several parameters, including interaction with antagonistic flora such as Lactococcus lactis, a lactic acid bacterium widely used in the dairy industry, can modulate S. aureus proliferation and virulence expression. We developed a dedicated S. aureus microarray to investigate the effect of L. lactis on staphylococcal gene expression in mixed cultures. This microarray was used to establish the transcriptomic profile of S. aureus in mixed cultures with L. lactis in a chemically defined medium held at a constant pH (6.6). Under these conditions, L. lactis hardly affected S. aureus growth. The expression of most genes involved in the cellular machinery, carbohydrate and nitrogen metabolism, and stress responses was only slightly modulated: a short time lag in mixed compared to pure cultures was observed. Interestingly, the induction of several virulence factors and regulators, including the agr locus, sarA, and some enterotoxins, was strongly affected. This work clearly underlines the complexity of L. lactis antagonistic potential for S. aureus and yields promising leads for investigations into nonantibiotic biocontrol of this major pathogen.
Collapse
|
8
|
|
9
|
HUANG CHIACHERNG, LIN CHINWEN. Drying Temperature and Time Affect Quality of Chinese-style Sausage Inoculated with Lactic Acid Bacteria. J Food Sci 1993. [DOI: 10.1111/j.1365-2621.1993.tb04249.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
10
|
Metaxopoulos J, Genigeorgis C, Fanelli MJ, Franti C, Cosma E. Production of Italian Dry Salami: Effect of Starter Culture and Chemical Acidulation on Staphylococcal Growth in Salami Under Commercial Manufacturing Conditions. Appl Environ Microbiol 1981; 42:863-71. [PMID: 16345888 PMCID: PMC244120 DOI: 10.1128/aem.42.5.863-871.1981] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effect of starter culture and chemical acidulation on the growth and enterotoxigenesis of
Staphylococcus aureus
strain S-6 in Italian dry salami under commercial manufacturing conditions was studied. The experimental design included two levels of
S. aureus
(10
4
and 10
5
/g), three levels of starter culture (0, 10
5
, and 10
6
/g), three levels of initial pH (pH
0
) (6.1, 5.5, and 4.8), two manufacturing plants, and three replications.
S. aureus
growth in the salami was affected significantly (
P
< 0.005) by pH
0
, initial levels of
S. aureus
(staph
0
) and lactic acid bacteria (LAB
0
), day of fermentation, and by the interactions of pH
0
× day, pH
0
× LAB
0
, LAB
0
× staph
0
, pH
0
× staph
0
, and pH
0
× location of fermentation. In general, the lower the pH
0
and the higher the LAB
0
, the greater the inhibition of
S. aureus
. The LAB levels during the fermentation were affected significantly (
P
< 0.005) by pH
0
, LAB
0
, day of fermentation, location, LAB
0
× pH
0
, and LAB
0
× day. Derived regression equations related level of
S. aureus
and LAB at any day of fermentation to a number of microbiological and chemical variables. Close similarity of observed and predicted levels of
S. aureus
and LAB growth demonstrated the usefulness of the experimental approach in evaluating the safety of a process. No detectable enterotoxin or thermonuclease was found at any stage of processing even when
S. aureus
reached levels of 10
7
/g of salami.
Collapse
Affiliation(s)
- J Metaxopoulos
- Department of Epidemiology and Preventive Medicine, School of Veterinary Medicine, University of California, Davis, California 95616
| | | | | | | | | |
Collapse
|
11
|
Niskanen A, Nurmi E. Effect of starter culture on staphylococcal enterotoxin and thermonuclease production in dry sausage. Appl Environ Microbiol 1976; 31:11-20. [PMID: 942200 PMCID: PMC169710 DOI: 10.1128/aem.31.1.11-20.1976] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Different amounts of enterotoxin A-, B-, and C1-producing staphylococci were added to dry sausage prepared by normal processes, either alone or in conjunction with a starter culture (micrococci and lactobacilli). The sausage was examined after 0, 3, 7, 14, and 30 days for staphylococci, micrococci, and lactobacilli, and measurements were made of water activity, pH, enterotoxin, and thermostable nuclease. The results showed that in the absence of starter culture measurable amounts of enterotoxin A were formed in a 200-g sample of dry sausage in 3 days, the level of Staphylococcus aureus infection being over 10(6) cells/g. Enterotoxin B was not found, although the total number of staphylococci was over 10(8) cells/g. Enterotoxin C1 was observed when the Staphylococcus count was about 8 X 10(7) cells/g, but was no longer detectable after 7 days. The starter culture prevented the production of enterotoxin A in all cases investigated. By contrast, a very high-level inoculation of an enterotoxin C1-producing strain gave a positive result after 3 days of incubation even in the presence of a starter culture. Heat-stable nuclease was observed in all sausages to which enterotoxin-producing staphylococci were added. The cell count determined in a sample of sausage had no definite correlation with the thermonuclease activity of the sample.
Collapse
|
12
|
Fleming HP, Etchells JL, Costilow RN. Microbial Inhibition by an Isolate of
Pediococcus
from Cucumber Brines. Appl Microbiol 1975; 30:1040-2. [PMID: 16350041 PMCID: PMC376587 DOI: 10.1128/am.30.6.1040-1042.1975] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We reported earlier that
Pediococcus cerevisiae
FBB-61 inhibited
Lactobacillus plantarum
FBB-67 in mixed species inoculation used for the fermentation of brined cucumbers. Herein, 16 isolates of the
Pediococcus
genus from various sources were tested for inhibitory activity against
L. plantarum
and other microorganisms by a seeded-agar screening technique. Only two of the 16 isolates gave consistent and distinctive zones of inhibition, and both were isolated from fermenting cucumber brines on separate occasions. These two isolates did not inhibit each other but did inhibit the other 14
Pediococcus
isolates in addition to
L. plantarum
. They also inhibited several other gram-positive bacteria, but not four species each of gram-negative bacteria and yeasts tested. Inoculation of cucumber juice broth with
P. cerevisiae
FBB-61 and
L. plantarum
WSO resulted in a drastic reduction in the plate count of
L. plantarum
WSO during day 1, but counts increased rapidly thereafter. Consequently, acid production by
L. plantarum
WSO was delayed. Noninhibitory isolates of
Pediococcus
had no appreciable effect on growth and acid production by
L. plantarum
WSO.
Collapse
Affiliation(s)
- H P Fleming
- Food Fermentation Laboratory, Agricultural Research Service, U. S. Department of Agriculture, and North Carolina Agricultural Experiment Station, Raleigh, North Carolina 27607
| | | | | |
Collapse
|
13
|
Mickelson MJ, Klipstein FA. Enterotoxigenic intestinal bacteria in tropical sprue. IV. Effect of linoleic acid on growth interrelationships of Lactobacillus acidophilus and Klebsiella pneumoniae. Infect Immun 1975; 12:1121-6. [PMID: 811564 PMCID: PMC415407 DOI: 10.1128/iai.12.5.1121-1126.1975] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The factors responsible for colonization of the small intestine by enterotoxigenic coliform bacteria in Puerto Ricans with tropical sprue are unknown, but epidemiological observations have suggested that they may be related to an increased dietary intake of long-chain unsaturated fatty acids, particularly linoleic acid, which is known to exert an inhibitory effect on the growth of gram-positive organisms that normally comprise the flora of the small intestine. We have examined, by using a glucose-limited continuous-culture system, what effect this fatty acid exerts on the growth relationships of enteric gram-positive and coliform bacteria. In this system, colonization by an invading strain of Klebsiella pneumoniae was prevented by the presence of an established culture of Lactobacillus acidophilus, principally by virtue of a lowered pH of the medium that was incompatible with Klebsiella growth. However, when the population density of L. acidophilus was reduced by the presence of a sufficient concentration of linoleic acid, the invading K. pneumoniae successfully colonized the system and, once established, suppressed the growth of L. acidophilus. These observations indicate that, under the conditions of our chemostat, gram-positive enteric bacteria suppress coliform growth and that this effect is reversible by the presence of linoleic acid. It remains to be established, however, what pertinence these in vitro observations have to conditions within the intestinal tract of persons living in the tropics.
Collapse
|
14
|
Gilliland SE, Speck ML. Antagonism of lactic streptococci toward Staphylococcus aureus in associative milk cutures. Appl Microbiol 1974; 28:1090-3. [PMID: 4217589 PMCID: PMC186893 DOI: 10.1128/am.28.6.1090-1093.1974] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The inhibition of growth of Staphylococcus aureus by lactic streptococci in associative cultures in milk was not due to hydrogen peroxide produced by the streptococci. Dialyzed whey from the milk culture of lactic streptococci was more inhibitory than dialyzed whey from milk acidified with lactic acid, indicating that material other than lactate was also involved. Analyses of cation and anion exchange fractions from the dialyzed whey showed that only the neutral fraction was inhibitory.
Collapse
|