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Nature of the antimicrobial activity of Lactobacillus caseiBifidobacterium bifidum and Bifidobacterium animalis against foodborne pathogenic and spoilage microorganisms a
b
Cybelle Pereira de Oliveira , João Andrade da Silva & José Pinto de Siqueira-Júnior
a
a
Click for updates
Laboratory of Genetics of Microorganisms, DBM, CCEN, UFPB, João Pessoa, Brazil b
DTA, CTDR, UFPB, João Pessoa, Brazil Published online: 23 Dec 2014.
To cite this article: Cybelle Pereira de Oliveira, João Andrade da Silva & José Pinto de SiqueiraJúnior (2014): Nature of the antimicrobial activity of Lactobacillus caseiBifidobacterium bifidum and Bifidobacterium animalis against foodborne pathogenic and spoilage microorganisms, Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2014.989844 To link to this article: http://dx.doi.org/10.1080/14786419.2014.989844
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
Natural Product Research, 2014 http://dx.doi.org/10.1080/14786419.2014.989844
SHORT COMMUNICATION Nature of the antimicrobial activity of Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium animalis against foodborne pathogenic and spoilage microorganisms
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
Cybelle Pereira de Oliveiraa*, Joa˜o Andrade da Silvab and Jose´ Pinto de Siqueira-Ju´niora a Laboratory of Genetics of Microorganisms, DBM, CCEN, UFPB, Joa˜o Pessoa, Brazil; bDTA, CTDR, UFPB, Joa˜o Pessoa, Brazil
(Received 22 July 2014; final version received 13 November 2014)
The antimicrobial activities as well as the nature of the inhibitory compounds obtained from Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium animalis strains were assayed on foodborne pathogenic – Staphyloccoccus aureus subsp. aureus (CCUG ATCCw 25926e) and Escherichia coli (ATCCw 25922e) – and spoilage microorganisms – Pseudomonas aeruginosa (ATCCw 27853e). Test producer strains showed inhibitory effect on all indicator microorganisms in diffusion of cell-free concentrated supernatant by agar in well methods (10.0 –22.5 mm) in periods of 24, 48 and 72 h. Inhibitory compounds showed no sensitivity to the action of proteolytic enzyme trypsin and were completely inactivated by adjusting the pH of the cell-free 20 £ concentrated supernatant to 7.0. The results demonstrated that antimicrobial substances do not have proteinaceous nature and are caused by the action of organic acids with decreasing medium pH. Keywords: antimicrobial compounds; Lactobacillus; Bifidobacterium; organic acids
1. Introduction Lactic acid bacteria (LAB), usually represented by the genus Lactobacillus, are an important heterogeneous group of non-sporulated Gram-positive microorganisms widespread in nature. Many of these species have applications in the food industry and are used in the fermentation and as starter cultures in dairy and meat products, being related with pH reduction and with the production of an aroma-generating effect due to their metabolism, as well as the production of enzymes for catalytic and/or hydrolysis processes in food, especially proteases and lipases, which influence the maturation of some products (Pereira & Go´mez 2007; Va´squez et al. 2009).
*Corresponding author. Email: [email protected] q 2014 Taylor & Francis
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
2
C.P. de Oliveira et al.
Bifidobacteria (genus Bifidobacterium) are commonly accepted as a member of the LAB group, although phylogenetically distant from this group due to the presence of fructose 6phosphate fosfocetolase (P6PPK), responsible for the fermentation of hexoses and production of lactic acid and acetic acid in the ratio of 2:3, while in the metabolism of Lactobacillus, mainly lactic acid production occurs. In addition, the highest content (% by mol) of guanine and cytosine in the DNA of bifidobacteria is particularly different from the content in the DNA of Lactobacillus (Costa et al. 2012). The ability to reduce or eliminate enteropathogens demonstrated by many Lactobacillus and Bifidobacterium strains is one of the most important characteristics attributed to these bacteria, arousing interest in the biopreservation of foods with inhibitory activity against other microorganisms due to their potential antibacterial properties attributed to the end-products of their metabolism. In general, this effect is associated with the production of organic acids, hydrogen peroxide (H2O2), bacteriocins, bacterial peptides or active proteins (Va´squez et al. 2009; Costa et al. 2012). Thus, there is a great practical interest in the continuity of research for the identification of these bacterial strains (Pereira & Go´mez 2007). Thus, this study aimed to evaluate the in vitro antimicrobial activity of two LAB strains of the genus Lactobacillus casei, one Bifidobacterium bifidum strain and one Bifidobacterium animalis strain against pathogenic – Staphyloccoccus aureus subsp. aureus (CCUG ATCCw 25926e) and Escherichia coli (ATCCw 25922e) – and food spoilage – Pseudomonas aeruginosa (ATCCw 27853e) – microorganisms, as well to evaluate the nature of the compound responsible for such inhibition. 2. Results and discussion When evaluating the diffusion of antimicrobial activity of cell-free 20 £ concentrated supernatant by lyophilisation and resuspended in 3-(Nmorpholino-propanesulfonic acid) buffer using the agar diffusion wells method, the presence of antimicrobial activity of all producer strains on indicator strains was verified, even after separation of the biomass contained in the culture broth by means of centrifugation or filtration. Concentrating the supernatant 20 times was required because the inhibitory antimicrobial activity against pathogens and food spoilage microorganisms was not detected when using only the cell-free supernatant, centrifuged and filtered, or even concentrating it 10 £ by lyophilisation followed by resuspension in buffer. The data presented showed no statistically significant difference in the diameters of inhibition halos of the test producer strains on all four indicator strains in the periods of 24, 48 and 72 h, verifying, in this case, the influence of factor time on the production of antimicrobial compounds. These halos ranged in millimetres from 10.0 to 16.5 in L. casei lyophilised (Lc-l), from 14.0 to 18.0 in L. casei isolated (Lc-i), from 12.5 to 22.5 in B. bifidum lyophilised (Bb-l) and from 11.5 to 20.0 in B. animalis isolated (Ba-i), in the period up to 72 h (Table S1). Silva et al. (2010) evaluated the antimicrobial activity of Lactobacillus reuteri against food interest bacteria by the agar diffusion method and found positive inhibition results for E. coli and S. aureus indicator strains, with average inhibition halos of 2.3 and 4.3 mm, respectively. However, they used a supernatant free from cells by centrifugation and filtration, without the need for lyophilisation or concentration, which explains the formation of smaller halos. The antimicrobial activities performed by producer strains may be related to the action of various compounds such as organic acids, H2O2 and bacteriocins. According to Prado et al. (2000), the lyophilisation process itself promotes the removal of oxygen metabolites and H2O2. Rodriguez et al. (1997) emphasise that H2O2 is a compound rapidly degraded in the de Man, Rogosa and Sharpe (MRS) broth. Therefore, the possibility of the antimicrobial activity demonstrated here by the four test producer strains related to the action of H2O2 is excluded, since MRS was the medium used for growth of test producer strains and lyophilisation was the
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
Natural Product Research
3
technique used to concentrate the supernatant for later resuspension in the buffer. Antimicrobial compounds of proteinaceous nature such as bacteriocins can both be sensitive to various enzymes and resistant to one or the other (Pereira & Go´mez 2007). However, digestive enzymes trypsin and pepsin are commonly used to verify the proteolytic enzyme action on these compounds, since it is said that bacteriocins are digested by digestive enzymes (Moreno & Franco 2002). The antimicrobial activity related to the action of organic acids can be determined by adjusting the pH of the concentrated supernatant to 7.0. Experimental data (Table S2) demonstrated that the antimicrobial compounds produced are not affected by the enzymatic action of trypsin, not linking these compounds to a protein nature. The absence of inhibition zones resulting from the action of the enzyme solution as a control and the presence of inhibition zones related to the action of the supernatant solution as a control justify the antibacterial activity detected, as the antibacterial compounds in the supernatant were concentrated 20 £ , excluding the possibility of trypsin as an antimicrobial agent as well as the inhibition of possible proteinaceous compounds in the supernatant by this enzyme. In this research, the concentrated supernatants from all test producer strains were sensitive to neutralisation with 4 M NaOH solution in periods of 24, 48 and 72 h, completely losing their inhibitory capacity against S. aureus, E. coli and P. aeruginosa strains (Table S3). Thus, the antimicrobial activities observed in this experiment are related to the action of organic acids by acidification of the medium. The same result was presented by Pereira and Go´mez (2007), when evaluating the antimicrobial potential of a commercial L. acidophilus strain on foodborne E. coli and S. aureus. Organic acids contribute to the control of microorganisms, reducing the pH of foods, which is unfavourable to the survival and proliferation of Gram-positive and Gramnegative bacteria as well as fungi and yeasts (Tamanini et al. 2012). It is emphasised that the antimicrobial activity of LAB strains on food interest microorganisms occurs primarily by the production of organic acids. The production of bacteriocins by LAB strains is well studied; however, studies on the production of compounds of proteinaceous nature are less frequent (Gonza´lez et al. 2007; Pereira & Go´mez 2007; Castro et al. 2011).
3. Conclusions The four strains evaluated, two L. casei, one B. bifidum and one B. animalis, demonstrated antibacterial potential once they showed activity against S. aureus subsp. aureus (CCUG ATCCw 25926e), E. coli (ATCCw 25922e) and P. aeruginosa (ATCCw 27853e) for periods of 24, 48 and 72 h in diffusion of cell-free concentrated supernatant by agar in wells. However, the inhibitory compounds in 20 £ concentrated supernatant seemed to be unaffected by the proteolytic action of the trypsin enzyme, showing no protein origin such as bacteriocins or similar compounds. By adjusting the pH of the cell-free concentrated supernatants to 7.0, antimicrobial compounds had their activities inhibited, relating the nature of these substances to organic acids.
Supplementary material Experimental details relating to this article are available online, alongside Tables S1 –S3.
References Castro MP, Palavecino NZ, Herman C, Garro OA, Campos CA. 2011. Lactic acid bacteria isolated from artisanal dry sausages: characterization of antibacterial compounds and study of the factors affecting bacteriocin production. Meat Sci. 87:321–329.
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
4
C.P. de Oliveira et al.
Costa GNC, Suguimoto HH, Miglioranza LHS, Go´mez RJHC. 2012. Antimicrobial activity of Lactobacillus and Bifidobacterium against pathogenic microorganisms ‘in vitro’. Sem Ci Agra. 33:1839–1846. Gonza´lez L, Sandoval H, Sacrista´n N, Castro JM, Fresno JM, Tornadijo ME. 2007. Identification of lactic acid bacteria isolated from Genestoso cheese throughout ripening and study of their antimicrobial activity. Food Control. 18:716–722. Moreno CR, Franco BDGM. 2002. Bacteriocins of lactic acid bacteria. ConScientie Sau´de. 1:9–15. Pereira VG, Go´mez RJHC. 2007. Antimicrobial activity of Lactobacillus acidophilus against foodborne pathogens. Sem Ci Agra. 28:229–240. Prado CS, Santos WLM, Carvalho CR, Moreira EC, Costa JO. 2000. Antimicrobial activity of lactic acid bacteria cured built against Listeria monocytogenes. Arq Bras Med Vet Zootec. 52:417–423. Rodriguez JM, Martinez MI, Sua´rez AM, Martı´nez JM, Herna´ndez PE. 1997. Research note: unsuitability of the MRS medium for the screening of hydrogen peroxide-producing lactic bacteria. Lett Appl Microbiol. 25:73–74. Silva HS, Ramos RJ, Cirolini A, Miotto M, Bassegio AM, Vieira CRW. 2010. Antimicrobial activity of Lactobacillus reuteri against food interest bacteria. Rev Inst Adolfo Lutz. 69:584–587. Tamanini RT, Beloti V, Silva LCC, Angela HL, Yamad AK, Battaglini APP, Fagnani R, Monteiro AA. 2012. Antagonistic activity against Listeria monocytogenes and Escherichia coli from lactic acid bacteria isolated from raw milk. Sem Ci Agra. 33:1877– 1886. Va´squez SM, Suarez HY, Zapata S. 2009. Use of antimicrobial substances produced by lactic acid bacteria in meat preservation. Rev Chil Nutr. 36:64–71.
Natural Product Research: Formerly Natural Product Letters Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gnpl20
Nature of the antimicrobial activity of Lactobacillus caseiBifidobacterium bifidum and Bifidobacterium animalis against foodborne pathogenic and spoilage microorganisms a
b
Cybelle Pereira de Oliveira , João Andrade da Silva & José Pinto de Siqueira-Júnior
a
a
Click for updates
Laboratory of Genetics of Microorganisms, DBM, CCEN, UFPB, João Pessoa, Brazil b
DTA, CTDR, UFPB, João Pessoa, Brazil Published online: 23 Dec 2014.
To cite this article: Cybelle Pereira de Oliveira, João Andrade da Silva & José Pinto de SiqueiraJúnior (2014): Nature of the antimicrobial activity of Lactobacillus caseiBifidobacterium bifidum and Bifidobacterium animalis against foodborne pathogenic and spoilage microorganisms, Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2014.989844 To link to this article: http://dx.doi.org/10.1080/14786419.2014.989844
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
Natural Product Research, 2014 http://dx.doi.org/10.1080/14786419.2014.989844
SHORT COMMUNICATION Nature of the antimicrobial activity of Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium animalis against foodborne pathogenic and spoilage microorganisms
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
Cybelle Pereira de Oliveiraa*, Joa˜o Andrade da Silvab and Jose´ Pinto de Siqueira-Ju´niora a Laboratory of Genetics of Microorganisms, DBM, CCEN, UFPB, Joa˜o Pessoa, Brazil; bDTA, CTDR, UFPB, Joa˜o Pessoa, Brazil
(Received 22 July 2014; final version received 13 November 2014)
The antimicrobial activities as well as the nature of the inhibitory compounds obtained from Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium animalis strains were assayed on foodborne pathogenic – Staphyloccoccus aureus subsp. aureus (CCUG ATCCw 25926e) and Escherichia coli (ATCCw 25922e) – and spoilage microorganisms – Pseudomonas aeruginosa (ATCCw 27853e). Test producer strains showed inhibitory effect on all indicator microorganisms in diffusion of cell-free concentrated supernatant by agar in well methods (10.0 –22.5 mm) in periods of 24, 48 and 72 h. Inhibitory compounds showed no sensitivity to the action of proteolytic enzyme trypsin and were completely inactivated by adjusting the pH of the cell-free 20 £ concentrated supernatant to 7.0. The results demonstrated that antimicrobial substances do not have proteinaceous nature and are caused by the action of organic acids with decreasing medium pH. Keywords: antimicrobial compounds; Lactobacillus; Bifidobacterium; organic acids
1. Introduction Lactic acid bacteria (LAB), usually represented by the genus Lactobacillus, are an important heterogeneous group of non-sporulated Gram-positive microorganisms widespread in nature. Many of these species have applications in the food industry and are used in the fermentation and as starter cultures in dairy and meat products, being related with pH reduction and with the production of an aroma-generating effect due to their metabolism, as well as the production of enzymes for catalytic and/or hydrolysis processes in food, especially proteases and lipases, which influence the maturation of some products (Pereira & Go´mez 2007; Va´squez et al. 2009).
*Corresponding author. Email: [email protected] q 2014 Taylor & Francis
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
2
C.P. de Oliveira et al.
Bifidobacteria (genus Bifidobacterium) are commonly accepted as a member of the LAB group, although phylogenetically distant from this group due to the presence of fructose 6phosphate fosfocetolase (P6PPK), responsible for the fermentation of hexoses and production of lactic acid and acetic acid in the ratio of 2:3, while in the metabolism of Lactobacillus, mainly lactic acid production occurs. In addition, the highest content (% by mol) of guanine and cytosine in the DNA of bifidobacteria is particularly different from the content in the DNA of Lactobacillus (Costa et al. 2012). The ability to reduce or eliminate enteropathogens demonstrated by many Lactobacillus and Bifidobacterium strains is one of the most important characteristics attributed to these bacteria, arousing interest in the biopreservation of foods with inhibitory activity against other microorganisms due to their potential antibacterial properties attributed to the end-products of their metabolism. In general, this effect is associated with the production of organic acids, hydrogen peroxide (H2O2), bacteriocins, bacterial peptides or active proteins (Va´squez et al. 2009; Costa et al. 2012). Thus, there is a great practical interest in the continuity of research for the identification of these bacterial strains (Pereira & Go´mez 2007). Thus, this study aimed to evaluate the in vitro antimicrobial activity of two LAB strains of the genus Lactobacillus casei, one Bifidobacterium bifidum strain and one Bifidobacterium animalis strain against pathogenic – Staphyloccoccus aureus subsp. aureus (CCUG ATCCw 25926e) and Escherichia coli (ATCCw 25922e) – and food spoilage – Pseudomonas aeruginosa (ATCCw 27853e) – microorganisms, as well to evaluate the nature of the compound responsible for such inhibition. 2. Results and discussion When evaluating the diffusion of antimicrobial activity of cell-free 20 £ concentrated supernatant by lyophilisation and resuspended in 3-(Nmorpholino-propanesulfonic acid) buffer using the agar diffusion wells method, the presence of antimicrobial activity of all producer strains on indicator strains was verified, even after separation of the biomass contained in the culture broth by means of centrifugation or filtration. Concentrating the supernatant 20 times was required because the inhibitory antimicrobial activity against pathogens and food spoilage microorganisms was not detected when using only the cell-free supernatant, centrifuged and filtered, or even concentrating it 10 £ by lyophilisation followed by resuspension in buffer. The data presented showed no statistically significant difference in the diameters of inhibition halos of the test producer strains on all four indicator strains in the periods of 24, 48 and 72 h, verifying, in this case, the influence of factor time on the production of antimicrobial compounds. These halos ranged in millimetres from 10.0 to 16.5 in L. casei lyophilised (Lc-l), from 14.0 to 18.0 in L. casei isolated (Lc-i), from 12.5 to 22.5 in B. bifidum lyophilised (Bb-l) and from 11.5 to 20.0 in B. animalis isolated (Ba-i), in the period up to 72 h (Table S1). Silva et al. (2010) evaluated the antimicrobial activity of Lactobacillus reuteri against food interest bacteria by the agar diffusion method and found positive inhibition results for E. coli and S. aureus indicator strains, with average inhibition halos of 2.3 and 4.3 mm, respectively. However, they used a supernatant free from cells by centrifugation and filtration, without the need for lyophilisation or concentration, which explains the formation of smaller halos. The antimicrobial activities performed by producer strains may be related to the action of various compounds such as organic acids, H2O2 and bacteriocins. According to Prado et al. (2000), the lyophilisation process itself promotes the removal of oxygen metabolites and H2O2. Rodriguez et al. (1997) emphasise that H2O2 is a compound rapidly degraded in the de Man, Rogosa and Sharpe (MRS) broth. Therefore, the possibility of the antimicrobial activity demonstrated here by the four test producer strains related to the action of H2O2 is excluded, since MRS was the medium used for growth of test producer strains and lyophilisation was the
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
Natural Product Research
3
technique used to concentrate the supernatant for later resuspension in the buffer. Antimicrobial compounds of proteinaceous nature such as bacteriocins can both be sensitive to various enzymes and resistant to one or the other (Pereira & Go´mez 2007). However, digestive enzymes trypsin and pepsin are commonly used to verify the proteolytic enzyme action on these compounds, since it is said that bacteriocins are digested by digestive enzymes (Moreno & Franco 2002). The antimicrobial activity related to the action of organic acids can be determined by adjusting the pH of the concentrated supernatant to 7.0. Experimental data (Table S2) demonstrated that the antimicrobial compounds produced are not affected by the enzymatic action of trypsin, not linking these compounds to a protein nature. The absence of inhibition zones resulting from the action of the enzyme solution as a control and the presence of inhibition zones related to the action of the supernatant solution as a control justify the antibacterial activity detected, as the antibacterial compounds in the supernatant were concentrated 20 £ , excluding the possibility of trypsin as an antimicrobial agent as well as the inhibition of possible proteinaceous compounds in the supernatant by this enzyme. In this research, the concentrated supernatants from all test producer strains were sensitive to neutralisation with 4 M NaOH solution in periods of 24, 48 and 72 h, completely losing their inhibitory capacity against S. aureus, E. coli and P. aeruginosa strains (Table S3). Thus, the antimicrobial activities observed in this experiment are related to the action of organic acids by acidification of the medium. The same result was presented by Pereira and Go´mez (2007), when evaluating the antimicrobial potential of a commercial L. acidophilus strain on foodborne E. coli and S. aureus. Organic acids contribute to the control of microorganisms, reducing the pH of foods, which is unfavourable to the survival and proliferation of Gram-positive and Gramnegative bacteria as well as fungi and yeasts (Tamanini et al. 2012). It is emphasised that the antimicrobial activity of LAB strains on food interest microorganisms occurs primarily by the production of organic acids. The production of bacteriocins by LAB strains is well studied; however, studies on the production of compounds of proteinaceous nature are less frequent (Gonza´lez et al. 2007; Pereira & Go´mez 2007; Castro et al. 2011).
3. Conclusions The four strains evaluated, two L. casei, one B. bifidum and one B. animalis, demonstrated antibacterial potential once they showed activity against S. aureus subsp. aureus (CCUG ATCCw 25926e), E. coli (ATCCw 25922e) and P. aeruginosa (ATCCw 27853e) for periods of 24, 48 and 72 h in diffusion of cell-free concentrated supernatant by agar in wells. However, the inhibitory compounds in 20 £ concentrated supernatant seemed to be unaffected by the proteolytic action of the trypsin enzyme, showing no protein origin such as bacteriocins or similar compounds. By adjusting the pH of the cell-free concentrated supernatants to 7.0, antimicrobial compounds had their activities inhibited, relating the nature of these substances to organic acids.
Supplementary material Experimental details relating to this article are available online, alongside Tables S1 –S3.
References Castro MP, Palavecino NZ, Herman C, Garro OA, Campos CA. 2011. Lactic acid bacteria isolated from artisanal dry sausages: characterization of antibacterial compounds and study of the factors affecting bacteriocin production. Meat Sci. 87:321–329.
Downloaded by [University of Wyoming Libraries] at 05:20 30 March 2015
4
C.P. de Oliveira et al.
Costa GNC, Suguimoto HH, Miglioranza LHS, Go´mez RJHC. 2012. Antimicrobial activity of Lactobacillus and Bifidobacterium against pathogenic microorganisms ‘in vitro’. Sem Ci Agra. 33:1839–1846. Gonza´lez L, Sandoval H, Sacrista´n N, Castro JM, Fresno JM, Tornadijo ME. 2007. Identification of lactic acid bacteria isolated from Genestoso cheese throughout ripening and study of their antimicrobial activity. Food Control. 18:716–722. Moreno CR, Franco BDGM. 2002. Bacteriocins of lactic acid bacteria. ConScientie Sau´de. 1:9–15. Pereira VG, Go´mez RJHC. 2007. Antimicrobial activity of Lactobacillus acidophilus against foodborne pathogens. Sem Ci Agra. 28:229–240. Prado CS, Santos WLM, Carvalho CR, Moreira EC, Costa JO. 2000. Antimicrobial activity of lactic acid bacteria cured built against Listeria monocytogenes. Arq Bras Med Vet Zootec. 52:417–423. Rodriguez JM, Martinez MI, Sua´rez AM, Martı´nez JM, Herna´ndez PE. 1997. Research note: unsuitability of the MRS medium for the screening of hydrogen peroxide-producing lactic bacteria. Lett Appl Microbiol. 25:73–74. Silva HS, Ramos RJ, Cirolini A, Miotto M, Bassegio AM, Vieira CRW. 2010. Antimicrobial activity of Lactobacillus reuteri against food interest bacteria. Rev Inst Adolfo Lutz. 69:584–587. Tamanini RT, Beloti V, Silva LCC, Angela HL, Yamad AK, Battaglini APP, Fagnani R, Monteiro AA. 2012. Antagonistic activity against Listeria monocytogenes and Escherichia coli from lactic acid bacteria isolated from raw milk. Sem Ci Agra. 33:1877– 1886. Va´squez SM, Suarez HY, Zapata S. 2009. Use of antimicrobial substances produced by lactic acid bacteria in meat preservation. Rev Chil Nutr. 36:64–71.
