1
|
Lin L, Chen M, Ou J, Yan W. Kinetics of Staphylococcus aureus growth and Enterotoxin A production in milk under shaking and static conditions. Food Res Int 2021; 143:110298. [PMID: 33992318 DOI: 10.1016/j.foodres.2021.110298] [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: 11/02/2020] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 11/30/2022]
Abstract
Numerous studies on bacterial growth or survival predictive models have been conducted since the establishment of predictive microbiology. However, limited research focused on the prediction of bacteria-producing enterotoxins, which are often the causative agents of food-borne diseases. This study aimed to determine an appropriate kinetic model of staphylococcal enterotoxin A (SEA) production in milk after contamination with Staphylococcus aureus. An S. aureus strain producing SEA was inoculated into milk with an initial inoculum concentration of approximately 3.0 log CFU/mL. All samples were incubated for 30-48 h at 20 °C ± 1 °C, 28 °C ± 1 °C, and 36 °C ± 1 °C separately under shaking or static conditions. Duplicate samples were carried out at appropriate intervals to count the number of S. aureus colonies and detect the concentration of SEA. Experimental results showed that the SEA concentration curves under all experimental conditions were sigmoidal and consisted of three phases: lag, exponential, and stationary. Thus, the modified Gompertz model was used to describe the profile of SEA concentration in milk during the incubation. A good fitting accuracy (R2 > 0.97) indicated that the modified Gompertz model was appropriate. In addition to temperature, shaking during incubation also affected the maximal production rate of SEA and the maximal SEA concentrations, and shortened the lag phase at lower incubation temperatures, suggesting that the mechanical movements (e.g., stirring, pumping, and flowing) during the milk processing would increase the risk of SEA occurrence. Besides, the time to detection (TTD) of SEA was found to range from 3 to 24.5 h at temperatures of 36 °C ± 1 °C-20 °C ± 1 °C, at which time the concentrations of S. aureus ranging from 5.0 log CFU/mL-6.9 log CFU/mL at the TTD. This study contributed to understanding the kinetics of SEA production and the possible factors affecting the synthesis of SEA during the manufacturing of liquid foods, such as milk.
Collapse
Affiliation(s)
- Lu Lin
- Shanghai Food Research Institute, Shanghai 200235, China
| | - Min Chen
- Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China
| | - Jie Ou
- Shanghai Ocean University, Shanghai 201306, China
| | - Weiling Yan
- Shanghai Food Research Institute, Shanghai 200235, China.
| |
Collapse
|
2
|
Asimakoula S, Giaka K, Fanitsios C, Kakouri A, Vandera E, Samelis J, Koukkou AI. Monitoring Growth Compatibility and Bacteriocin Gene Transcription of Adjunct and Starter Lactic Acid Bacterial Strains in Milk. J Food Prot 2021; 84:509-520. [PMID: 33108438 DOI: 10.4315/jfp-20-317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/22/2020] [Indexed: 01/13/2023]
Abstract
ABSTRACT When developing protective starter cultures for application in cheese technologies, monitoring growth interactions between starter and adjunct lactic acid bacterial (LAB) species and in situ expression of bacteriocin genes in the mixtures is crucial. This study first aimed to monitor the growth of mixed LAB strain populations during milk model fermentations by microbial counts and real-time quantitative PCR. The primary starter strains, Streptococcus thermophilus ST1 and costarter Lactococcus lactis subsp. cremoris M78, served as the basic starter composite coinoculated in all milk treatments. Adjunct bacteriocinogenic Enterococcus faecium strains KE82 and GL31 and the ripening Lactiplantibacillus plantarum H25 strain were added separately to the starter composite, resulting in four LAB combination treatments. The second aim was to quantify gene transcripts of nisin and enterocins B and A synthesized by strains M78, KE82, and GL31, respectively, by reverse transcription-real-time quantitative PCR and to detect the in situ antilisterial effects of the cocultures. Adjunct LAB strains showed growth compatibility with the starter, since all of them exhibited 2- to 3-log-unit increases in their population levels compared to their initial inoculation levels, with ST1 prevailing in all treatments. KE82 grew more competitively than GL31, whereas cocultures with KE82 displayed the strongest in situ antilisterial activity. Nisin gene expression levels were higher at the exponential phase of microbial growth in all treatments. Finally, the expression levels of nisin and enterocin A and B genes were interrelated, indicating an antagonistic activity. HIGHLIGHTS
Collapse
Affiliation(s)
- Stamatia Asimakoula
- Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
| | - Katerina Giaka
- Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
| | - Christos Fanitsios
- Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
| | - Athanasia Kakouri
- Dairy Research Department, General Directorate of Agricultural Research, Hellenic Agricultural Organization DIMITRA, Katsikas, 45221 Ioannina, Greece
| | - Elpiniki Vandera
- Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
| | - John Samelis
- Dairy Research Department, General Directorate of Agricultural Research, Hellenic Agricultural Organization DIMITRA, Katsikas, 45221 Ioannina, Greece
| | - Anna-Irini Koukkou
- Laboratory of Biochemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece
| |
Collapse
|
3
|
Jakočiūnė D, Herrero-Fresno A, Jelsbak L, Olsen JE. Highly expressed amino acid biosynthesis genes revealed by global gene expression analysis of Salmonella enterica serovar Enteritidis during growth in whole egg are not essential for this growth. Int J Food Microbiol 2016; 224:40-6. [DOI: 10.1016/j.ijfoodmicro.2016.02.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 02/12/2016] [Accepted: 02/21/2016] [Indexed: 01/17/2023]
|
4
|
Fernández M, Hudson JA, Korpela R, de los Reyes-Gavilán CG. Impact on human health of microorganisms present in fermented dairy products: an overview. BIOMED RESEARCH INTERNATIONAL 2015; 2015:412714. [PMID: 25839033 PMCID: PMC4369881 DOI: 10.1155/2015/412714] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 09/04/2014] [Indexed: 02/07/2023]
Abstract
Fermented dairy products provide nutrients in our diet, some of which are produced by the action of microorganisms during fermentation. These products can be populated by a diverse microbiota that impacts the organoleptic and physicochemical characteristics foods as well as human health. Acidification is carried out by starter lactic acid bacteria (LAB) whereas other LAB, moulds, and yeasts become dominant during ripening and contribute to the development of aroma and texture in dairy products. Probiotics are generally part of the nonstarter microbiota, and their use has been extended in recent years. Fermented dairy products can contain beneficial compounds, which are produced by the metabolic activity of their microbiota (vitamins, conjugated linoleic acid, bioactive peptides, and gamma-aminobutyric acid, among others). Some microorganisms can also release toxic compounds, the most notorious being biogenic amines and aflatoxins. Though generally considered safe, fermented dairy products can be contaminated by pathogens. If proliferation occurs during manufacture or storage, they can cause sporadic cases or outbreaks of disease. This paper provides an overview on the current state of different aspects of the research on microorganisms present in dairy products in the light of their positive or negative impact on human health.
Collapse
Affiliation(s)
- María Fernández
- Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Paseo Río Linares s/n, Villaviciosa, 33300 Asturias, Spain
| | - John Andrew Hudson
- Food Safety Programme, ESR-Christchurch Science Centre, Christchurch 8540, New Zealand
- Food and Environment Safety Programme, The Food and Environment Research Agency, Sand Hutton, York YO41 1LZ, UK
| | - Riitta Korpela
- Medical Nutrition Physiology Group, Pharmacology, Institute of Biomedicine, University of Helsinki, 00014 Helsinki, Finland
| | - Clara G. de los Reyes-Gavilán
- Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Paseo Río Linares s/n, Villaviciosa, 33300 Asturias, Spain
| |
Collapse
|
5
|
Method enabling gene expression studies of pathogens in a complex food matrix. Appl Environ Microbiol 2011; 77:8456-8. [PMID: 21984236 DOI: 10.1128/aem.05471-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We describe a simple method for stabilizing and extracting high-quality prokaryotic RNA from meat. Heat and salt stress of Escherichia coli and Salmonella spp. in minced meat reproducibly induced dnaK and otsB expression, respectively, as observed by quantitative reverse transcription-PCR (>5-fold relative changes). Thus, the method is applicable in studies of bacterial gene expression in a meat matrix.
Collapse
|
6
|
Calles-Enríquez M, Eriksen BH, Andersen PS, Rattray FP, Johansen AH, Fernández M, Ladero V, Alvarez MA. Sequencing and transcriptional analysis of the Streptococcus thermophilus histamine biosynthesis gene cluster: factors that affect differential hdcA expression. Appl Environ Microbiol 2010; 76:6231-8. [PMID: 20656875 PMCID: PMC2937487 DOI: 10.1128/aem.00827-10] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 07/11/2010] [Indexed: 11/20/2022] Open
Abstract
Histamine, a toxic compound that is formed by the decarboxylation of histidine through the action of microbial decarboxylases, can accumulate in fermented food products. From a total of 69 Streptococcus thermophilus strains screened, two strains, CHCC1524 and CHCC6483, showed the capacity to produce histamine. The hdc clusters of S. thermophilus CHCC1524 and CHCC6483 were sequenced, and the factors that affect histamine biosynthesis and histidine-decarboxylating gene (hdcA) expression were studied. The hdc cluster began with the hdcA gene, was followed by a transporter (hdcP), and ended with the hdcB gene, which is of unknown function. The three genes were orientated in the same direction. The genetic organization of the hdc cluster showed a unique organization among the lactic acid bacterial group and resembled those of Staphylococcus and Clostridium species, thus indicating possible acquisition through a horizontal transfer mechanism. Transcriptional analysis of the hdc cluster revealed the existence of a polycistronic mRNA covering the three genes. The histidine-decarboxylating gene (hdcA) of S. thermophilus demonstrated maximum expression during the stationary growth phase, with high expression levels correlated with high histamine levels. Limited expression was evident during the lag and exponential growth phases. Low-temperature (4 degrees C) incubation of milk inoculated with a histamine-producing strain showed lower levels of histamine than did inoculated milk kept at 42 degrees C. This reduction was attributed to a reduction in the activity of the HdcA enzyme itself rather than a reduction in gene expression or the presence of a lower cell number.
Collapse
Affiliation(s)
- Marina Calles-Enríquez
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Benjamin Hjort Eriksen
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Pia Skov Andersen
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Fergal P. Rattray
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Annette H. Johansen
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - María Fernández
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Victor Ladero
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| | - Miguel A. Alvarez
- Instituto de Productos Lácteos de Asturias, CSIC, Crta. Infiesto s/n, 33300 Villaviciosa, Asturias, Spain, Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm, Denmark
| |
Collapse
|