Die Nahrung 34 (1990) 3, 273-277
Biology Department of Sciences and Arts, Anadolu University, EskiSehir, Turkey
Antagonistic action of lactic cultures toward spoilage and pathogenic microorganisms in food MERIHKIVANC
The antibacterial properties of cell-free filtrate from lactic cultures were assessed against 10 bacterial cultures. All the five species of lactic culture examin;d showed antimicrobial activity against tested bacteria. S. uuretls was least sensitive of the tested bacteria, followed by E. coli and S.typhosa. E. aerogenes was the most sensitive one. L. casei had the greatest antimicrobial activity. Leu. rnesenteroides weakly inhibited the growth of the tested bacteria. In general, inoculum density had little effect on inhibition.
Introduction
Streptococcus lactis, Streptococcus cremoris and Lactobacillus casei are known to dominate other lactic acid bacteria in mixed cheese starter cultures. Lactobacillus plantarum is useful in the manufacture of extremely different food products, especially meat products, and Lactobacillus mesenteroides was more common especially in pickling [14, 20,211. Lactic acid bacteria are widely used to produce a variety of foods with desirable flavor, texture or other characteristics. An additional benefit which may result from use of these bacteria is the inhibition and/or inactivation of certain microorganisms able to cause spoilage of foodborn illness. That lactic acid bacteria produce acid and possibly other substances which can influence growth and/or survival of other bacteria is well recognized [ l l , 151. Several investigators [3, 7 , 9 , 10, 16, 19,241have reported that lactic acid bacteria inhibits a wide variety of spoilage and pathogenic organisms in a variety of food products such as skim milk, butter, vanilla creamfilling, ham sandwiches, bread soy milk and ground beef, sausage and beefburger. Meat and dairy products are suitable media for growth of many kinds of bacteria, including certain pathogens, and because the bacteria may enter the food, the environment or the food Pseudomonas fluorescens, Pseudomonas fragi, Alcaligenes metalcaligenes, Vibrio parahaemolyticus, Pseudomonas aeruginosa, Clostridium perfringens, Shigella sonnei, Escherichia market dealer, occasional outbreaks of disease traceable to dairy and meat products still occur in spite of advances in food manufacturing processes [5, 121. The spent medium as well as washed cells of lactic acid bacteria inhibit the growth of coli and Salmonella hennessee [5, 61. Several investigators have used different methods for estimating antimicrobial substances produced by lactic acid bacteria [5, 13,211. The purpose of this study was to determine antibacterial activity of cellfree filtrate from lactic cultures against spoilage and pathogenic organisms in a variety of food products.
274
Die Nahrung 34 (1990) 3
Material and methods Source of cultures Five species of lactic acid bacteria, including Streptococcus lactis, Streptococcus crernoris, Lactobacillus casei, Lactobacillus plantarum, Leuconostoc mesenteroides were obtained from the USDA, Agricultural Research Service, Midwest Area, Northern Reeional Research Center, Peoria, Ill. USA. Bacillus cereus, Bacillus rnegaterium, Bacillus subtilis, Escherichia coli, Enterobacter aerogenes, Salmonella typhimurium, Staphylococcus aureus, Streptococcus faecali.5, Pseudornonas aeroginosa, Proteus vulgaris were obtained from Bundesanstalt fur Fleischforschung (Kulmbach, FRG). All lactic cultures were maintained in litmus milk by routine weekly transfer. Pathogenic bacterial cultures were maintained on brain heart infusion agar slants, other bacterial cultures were maintained on nutrient agar slants.
Media The following media were used in this study:(a) AFT broth, (b) AFT agar, (c) nutrient broth (d) nutrient agar (e) brain heart infusion agar (0 litmus milk. All the above media except litmus milk, were autoclaved at 103 kPa for 20 min, litmus milk was steamed for 30 min on three consecutive days.
Fermentation A 16-h culture of lactic acid bacteria were inoculated (1 % by volume) into 100 ml conical flasks containing 50 ml of APT broth and incubated for 24,48 and 72 h at 30 "C. The cell-free filtrate was obtained by centrifuging cultures at 15000 x g for 15 min. The pH of the cellfree filtrate was adjusted to 4.5 and the filtrate was autoclaved at 103 kPa for 20 min.
Well assay method The assay medium was melted, tempered to 45 2 "C and 2 04Tween 80 was added and thoroughly mixed. To this medim, 16-hwashedcells of bacteria were addedto giveafinalinoculum of lo6 and lo3 cells/ml of nutrient agar. lOml of the inoculated medium were transferred to petri plates and allowed to solidify. The petri plates were placed in a refrigerator for, 1 h to facilitate the boring of wells in the medium. Five wells (6 mm diam.) were made in each petri plate using a sterile steel borer. Sterile culture filtrate (0.05 ml) was added to each well and the petri plates were left undisturbed for 1 h to facilitate diffusion of culture filtrate into the medium. The petri plates were then incubated at 37 "C for 16 to 24 h and the diameter of inhibitory zones was measured. Control assays were done using sterile APT broth instead of culture filtrates. All data presented are means of three seperate trials.
Results and discussion All the five species of lactic acid bacteria examined showed antibacterial activity against tested bacteria (Table 1). S. aureus was least sensitive of the tested followed by E. coli and S. typhosa. Whereas E. aerogenes was most sensitive. These results confirm the earlier observations of other researchers [l, 2, 5 , 61. ABDEL-BAR et al. [ l ] reported that S. aureus was not totally inhibited by Lactobacillus bulgaricus. ANGELO et al. [2] reported that a strain of S. lactis var. diacetilactis exhibited little inhibitory activity against S. aureus. S . diacetilactis and Lactobacillus citrovorum were not shown to inhibit S. aureus [5]. However, BASTEPE 141 reported that Streptococcus lactis, L. bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus inhibited the growth of S. aureus. The inhibitory activity of L . pluritarium
215
KIVANC:Action of lactic cultures
Table 1 Estimation of antibacterial activity of cell-free filtrate from lactic cultures Test Organisms Diameter of zone of inhibition [mm] ~~
S. lactis
24h
B. cereus
A
B B. megaterium A B B.subtilis A B S. aureus A B S. faecalis A B E. coli A B E. aerogenes A B P.aeroginosa A B P. vulgaris A B S. typhimurium A
B
L. casei
S. cremoris
48 h
10.3 10.7 11.0 11.3 12.7 13.0 16.0 16.3 10.0 10.7 10.3 11.0 7.0 8.3 7.3 7.7 15.0 15.7 15.3 15.3 8.3 10.3 9.0 10.7 17.3 18.0 20.0 20.7 11.3 11.7 12.0 12.3 13.7 14.0 20.0 20.7 8.0 8.0 9.0 9.0
72h
24h
L. plantarum
Leu. mesenterodes
24h
48 h
72 h
48 h
72 h
24 h
48 h
72 h
24h
48 h
72h
9.7 14.0 9.3 14.7 12.0 12.0 14.0 15.0 8.7 10.3 9.3 10.7 7.0 6.0 7.3 6.3 14.7 11.7 15.0 12.0 7.0 9.3 7.3 10.0 17.0 15.0 17.3 20.0 10.7 10.3 11.0 12.0 13.0 14.7 18.0 15.0 8.0 8.7 8.0 13.3
14.3 14.7 12.3 15.3 10.7 11.0 6.3 6.7 15.6 16.0 11.0 11.3 18.0 18.7 11.7 12.3 14.7 15.3 8.7 13.7
14.0 13.0 13.7 14.3 13.3 14.0 11.7 14.3 14.7 14.7 15.0 15.3 6.7 10.3 10.7 7.3 10.7 11.0 6.7 9.3 6.0 6.7 9.7 6.0 10.0 13.0 15.0 11.3 13.7 15.7 7.0 11.0 12.0 7.3 11.3 12.7 12.3 17.3 17.7 16.0 20.0 18.0 10.7 13.0 13.7 11.0 13.3 14.0 13.0 16.7 17.0 13.7 17.3 20.0 9.3 11.0 8.0 11.0 13.0 13.0
12.7 13.0 13.7 14.3 7.0 7.3 6.0 6.3 12.3 12.7 7.6 8.3 14.0 14.7 11.7 12.0 16.0 17.3 9.0 12.3
10.0 13.0 12.7 14.0 11.0 12.0 7.0 7.0 7.0 7.3 12.0 12.3 11.3 11.7 13.7 14.0 15.0 17.0 12.7 13.0
11.0 13.7 13.0 15.7 11.0 12.3 7.3 7.3 11.0 12.0 13.0 13.0 13.7 13.7 14.0 14.3 15.7 17.7 13.0 13.3
10.3 10.0 10.3 8.0 11.0 10.3 10.3 8.0 10.0 9.3 9.7 8.0 12.7 10.0 10.3 10.0 10.3 10.0 10.3 9.7 12.0 11.0 11.3 10.7 7.0 9.0 6.7 6.7 9.3 7.0 6.7 7.3 7.3 11.0 12.0 10.7 7.7 12.0 12.3 11.0 8.7 11.7 9.7 10.0 13.0 10.0 10.3 9.7 11.0 10.7 14.0 10.0 11.3 21.7 23.0 20.7 12.7 10.0 10.3 18.7 14.0 11.0 11.0 9.7 15.0 9.0 9.7 8.0 16.3 9.7 10.0 8.3 9.0 11.0 8.7 7.0 9.3 8.7 12.7 9.0
A 106 cell/ml B 103 celliml
against S. aureus was also reported by RACCACH et al. [20]. The extent of inhibition of microorganisms by lactic culture varies depending on the strain and other factors. We observed that, among the lactic culture L . casei had the greatest antimicrobial activity, whereas Leu. mesenteroides weakly inhibited growth of tested bacteria. Other lactic culture showed varying degrees of antimicrobial activity. PULUSANI et al. [17] reported that S. lactis weakly inhibited the growth of the P . aeroginosa and B. subtilis. Growth of Enterobacter cloacae and E. aerogenes was markedly inhibited by S. lactis and S. crernoris [24]. The antimicrobial activity of Leu. rnesenteroides and L . casei was not reported in the literature previously. In general, inoculum density had little effect on inhibition. The antimicrobial activity of cell-free filtrate from lactic cultures was generally greater against the gram negative than the gram positive organisms tested. These observations agree with those of other investigators [8,23]. However, GILLIAND et al. [l 11 reported that the gram positive bacteria were more sensitive to the inhibitory action of L . acidophilus than were the gram negative species, contrary to our results. It may be due to differences in the nature of strains or the type of suspending medium. Antimicrobial activity of lactic culture was maximum after 48 h of incubation and the activity dropped upon further incubation. This observation confirms an earlier report [5, 181. RAOet al. [18] reported that antimicrobial activity of S. therrnophilus grown in whole milk at 50 "C was maximum after 48 h of incubation. Inhibitory activity of various lactic cultures [4, 20-221 against the spoilage bacteria in foods apparently is due to the metabolites released by the lactic cultures, as has been suggested previously by GILLIAND et al. [12].
276
Die Nahrung 34 (1990) 3
Results of this investigation indicate that antimicrobial compound(s) are produced by lactic cultures. Apparently the antimicrobial substances are metabolites of lactic cultures rather than structural components of the lactic cultures. Therefore, the use of these organisms appears to have great potential for controlling the growth of food spoilage and pathogenic microorganisms in food. Zusammenfassung MERIHKIVANC : Antagonistische Wirkung von Milchsaurekulturen gegenuber Verderb hervorrufenden und pathogen wirkenden Mikroorganismen in Nahrungsmitteln Die antibakteriellen Eigenschaften zellfreier Filtrate von Milchsaurekulturen werden gegenuber 10 Bakterienkulturen gepriift. Alle 5 Species der gepriiften Milchsaurekulturen zeigen antimikrobielle Aktivitat gegenuber den getesteten Bakterh. S.aureus wird am wenigsten beeinflu& gefolgt von E. coli und S. typhosa. E. aerogenes erweist sich als am empfindlichsten. L. casei zeigt die hochste antimikrobielle Aktivitat. Leu. mesenteroides hemmt das Wachstum der gepriiften Bakterien nur schwach. Die Inokulum-Dichte hat im allgemeinen nur wenig EinfluD auf die Hemmung. Pem~e
References [l] ABDEL-BAR, N . M., and N. D. HARRIS,J. Food Protect. 47, 61-64 (1984). [2] ANGELO,I. A., K. M. SHAHANI and A. D. AYELO,J. Dairy Sci. 63 (Supplement), 52,(1980). [3] BABEL,F. J., J. Dairy Sci. 60,815-821 (1977). [4] BGTEPE,S. Bazi sut mamullerinden ayrilan koagulaz-pazitif Stafilococcus’ lar ve bunlafin gelismeleri iizerine siit asidi bakterilerinin etkisi (Doktora Tezi) Ankara. [5] BRANEN, A. L., H. C. Go and R. P. GENSKE,J. Food Sci. 40,446-450 (1975). [6] DALY,C., W. E. SANDINE and P. R. ELLIKER, J. Milk Food Technol. 35, 349-357 (1972). [7] EL-KHATBLB, T., and H. A. EL-RAHMAN, J. Food Protect. 50, 310-311 (1987). [8] GENSKE, R. P., and A. L. BRANEN, Modern Dairy 52, 12-14 (1973). [9] GILLILAND, S. E., and M. L. SPECK,J. Milk Food Technol. 35, 307-310 (1972). [lo] GILLILAND, S. E., and M. L. SPECK,J. Food Sci. 40, 903-905 (1975). [ l l ] GILLILAND, S. E., and M. L. SPECK,J. Food Prot. 40, 820-823 (1977). [I21 KEOGH,B. P., J. Dairy Res. 38, 91-111 (1971). [13] MARTIN,D. R., and S. E. GILLIAND, J. Food Protect. 43, 675-678 (1980). [I41 PAMIR,H., Fermentation microbiology (in Turkish), Ankara Univ. Fac. Agric. Publ. No. 936, Ankara 1985. [I51 PARK,H. S., and E. H. MARTH,J. Milk Food Technol. 35, 482-483 (1972). [I61 PRICE,R. J., and J. S. LEE.J. Milk Food Technol. 33, 13-18 (1970). S. R., D. R. RAOand G. R. SUNKI,J. Food Sci. 44,575-578 (1979). [17] PULUSANI, [18] RAO,D. R., and S. R. PULUSANI, J. Food Sci. 46,630-632 (1981).
KIVANG: Action of lactic cultures
277
RACCACH, M., and R. C. BAKER,J. Food Sci. 44, 90-92 (1979). RACCACH, M., R. C. BAKER,J. M. REGENSTEIN and E. J. MILNIX,J. Food Sci. 44, 43-46 (1979). REDDY,S. G., R. L. HENRICKSON and H. C. OLSON,J. Food Sci. 35, 787-789 (1970). REDDY,S. G., M. L. CHENand P. J. PATEL,,J. Food Sci. 40,314-316 (1975). REDDY,N. S., and B. RANGANATHAN, J. Food Protect. 46,222-225 (1983). RUTZINSKI, J. L., and E. H. MARTH,J. Food Protect. 43, 720-728 (1980). Dr. MERIHKIVANC,Biology Department, Faculty of Sciences and Arts, Anadolu University, EskiSehir, Turkey Received May 17, 1989
Biology Department of Sciences and Arts, Anadolu University, EskiSehir, Turkey
Antagonistic action of lactic cultures toward spoilage and pathogenic microorganisms in food MERIHKIVANC
The antibacterial properties of cell-free filtrate from lactic cultures were assessed against 10 bacterial cultures. All the five species of lactic culture examin;d showed antimicrobial activity against tested bacteria. S. uuretls was least sensitive of the tested bacteria, followed by E. coli and S.typhosa. E. aerogenes was the most sensitive one. L. casei had the greatest antimicrobial activity. Leu. rnesenteroides weakly inhibited the growth of the tested bacteria. In general, inoculum density had little effect on inhibition.
Introduction
Streptococcus lactis, Streptococcus cremoris and Lactobacillus casei are known to dominate other lactic acid bacteria in mixed cheese starter cultures. Lactobacillus plantarum is useful in the manufacture of extremely different food products, especially meat products, and Lactobacillus mesenteroides was more common especially in pickling [14, 20,211. Lactic acid bacteria are widely used to produce a variety of foods with desirable flavor, texture or other characteristics. An additional benefit which may result from use of these bacteria is the inhibition and/or inactivation of certain microorganisms able to cause spoilage of foodborn illness. That lactic acid bacteria produce acid and possibly other substances which can influence growth and/or survival of other bacteria is well recognized [ l l , 151. Several investigators [3, 7 , 9 , 10, 16, 19,241have reported that lactic acid bacteria inhibits a wide variety of spoilage and pathogenic organisms in a variety of food products such as skim milk, butter, vanilla creamfilling, ham sandwiches, bread soy milk and ground beef, sausage and beefburger. Meat and dairy products are suitable media for growth of many kinds of bacteria, including certain pathogens, and because the bacteria may enter the food, the environment or the food Pseudomonas fluorescens, Pseudomonas fragi, Alcaligenes metalcaligenes, Vibrio parahaemolyticus, Pseudomonas aeruginosa, Clostridium perfringens, Shigella sonnei, Escherichia market dealer, occasional outbreaks of disease traceable to dairy and meat products still occur in spite of advances in food manufacturing processes [5, 121. The spent medium as well as washed cells of lactic acid bacteria inhibit the growth of coli and Salmonella hennessee [5, 61. Several investigators have used different methods for estimating antimicrobial substances produced by lactic acid bacteria [5, 13,211. The purpose of this study was to determine antibacterial activity of cellfree filtrate from lactic cultures against spoilage and pathogenic organisms in a variety of food products.
274
Die Nahrung 34 (1990) 3
Material and methods Source of cultures Five species of lactic acid bacteria, including Streptococcus lactis, Streptococcus crernoris, Lactobacillus casei, Lactobacillus plantarum, Leuconostoc mesenteroides were obtained from the USDA, Agricultural Research Service, Midwest Area, Northern Reeional Research Center, Peoria, Ill. USA. Bacillus cereus, Bacillus rnegaterium, Bacillus subtilis, Escherichia coli, Enterobacter aerogenes, Salmonella typhimurium, Staphylococcus aureus, Streptococcus faecali.5, Pseudornonas aeroginosa, Proteus vulgaris were obtained from Bundesanstalt fur Fleischforschung (Kulmbach, FRG). All lactic cultures were maintained in litmus milk by routine weekly transfer. Pathogenic bacterial cultures were maintained on brain heart infusion agar slants, other bacterial cultures were maintained on nutrient agar slants.
Media The following media were used in this study:(a) AFT broth, (b) AFT agar, (c) nutrient broth (d) nutrient agar (e) brain heart infusion agar (0 litmus milk. All the above media except litmus milk, were autoclaved at 103 kPa for 20 min, litmus milk was steamed for 30 min on three consecutive days.
Fermentation A 16-h culture of lactic acid bacteria were inoculated (1 % by volume) into 100 ml conical flasks containing 50 ml of APT broth and incubated for 24,48 and 72 h at 30 "C. The cell-free filtrate was obtained by centrifuging cultures at 15000 x g for 15 min. The pH of the cellfree filtrate was adjusted to 4.5 and the filtrate was autoclaved at 103 kPa for 20 min.
Well assay method The assay medium was melted, tempered to 45 2 "C and 2 04Tween 80 was added and thoroughly mixed. To this medim, 16-hwashedcells of bacteria were addedto giveafinalinoculum of lo6 and lo3 cells/ml of nutrient agar. lOml of the inoculated medium were transferred to petri plates and allowed to solidify. The petri plates were placed in a refrigerator for, 1 h to facilitate the boring of wells in the medium. Five wells (6 mm diam.) were made in each petri plate using a sterile steel borer. Sterile culture filtrate (0.05 ml) was added to each well and the petri plates were left undisturbed for 1 h to facilitate diffusion of culture filtrate into the medium. The petri plates were then incubated at 37 "C for 16 to 24 h and the diameter of inhibitory zones was measured. Control assays were done using sterile APT broth instead of culture filtrates. All data presented are means of three seperate trials.
Results and discussion All the five species of lactic acid bacteria examined showed antibacterial activity against tested bacteria (Table 1). S. aureus was least sensitive of the tested followed by E. coli and S. typhosa. Whereas E. aerogenes was most sensitive. These results confirm the earlier observations of other researchers [l, 2, 5 , 61. ABDEL-BAR et al. [ l ] reported that S. aureus was not totally inhibited by Lactobacillus bulgaricus. ANGELO et al. [2] reported that a strain of S. lactis var. diacetilactis exhibited little inhibitory activity against S. aureus. S . diacetilactis and Lactobacillus citrovorum were not shown to inhibit S. aureus [5]. However, BASTEPE 141 reported that Streptococcus lactis, L. bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus inhibited the growth of S. aureus. The inhibitory activity of L . pluritarium
215
KIVANC:Action of lactic cultures
Table 1 Estimation of antibacterial activity of cell-free filtrate from lactic cultures Test Organisms Diameter of zone of inhibition [mm] ~~
S. lactis
24h
B. cereus
A
B B. megaterium A B B.subtilis A B S. aureus A B S. faecalis A B E. coli A B E. aerogenes A B P.aeroginosa A B P. vulgaris A B S. typhimurium A
B
L. casei
S. cremoris
48 h
10.3 10.7 11.0 11.3 12.7 13.0 16.0 16.3 10.0 10.7 10.3 11.0 7.0 8.3 7.3 7.7 15.0 15.7 15.3 15.3 8.3 10.3 9.0 10.7 17.3 18.0 20.0 20.7 11.3 11.7 12.0 12.3 13.7 14.0 20.0 20.7 8.0 8.0 9.0 9.0
72h
24h
L. plantarum
Leu. mesenterodes
24h
48 h
72 h
48 h
72 h
24 h
48 h
72 h
24h
48 h
72h
9.7 14.0 9.3 14.7 12.0 12.0 14.0 15.0 8.7 10.3 9.3 10.7 7.0 6.0 7.3 6.3 14.7 11.7 15.0 12.0 7.0 9.3 7.3 10.0 17.0 15.0 17.3 20.0 10.7 10.3 11.0 12.0 13.0 14.7 18.0 15.0 8.0 8.7 8.0 13.3
14.3 14.7 12.3 15.3 10.7 11.0 6.3 6.7 15.6 16.0 11.0 11.3 18.0 18.7 11.7 12.3 14.7 15.3 8.7 13.7
14.0 13.0 13.7 14.3 13.3 14.0 11.7 14.3 14.7 14.7 15.0 15.3 6.7 10.3 10.7 7.3 10.7 11.0 6.7 9.3 6.0 6.7 9.7 6.0 10.0 13.0 15.0 11.3 13.7 15.7 7.0 11.0 12.0 7.3 11.3 12.7 12.3 17.3 17.7 16.0 20.0 18.0 10.7 13.0 13.7 11.0 13.3 14.0 13.0 16.7 17.0 13.7 17.3 20.0 9.3 11.0 8.0 11.0 13.0 13.0
12.7 13.0 13.7 14.3 7.0 7.3 6.0 6.3 12.3 12.7 7.6 8.3 14.0 14.7 11.7 12.0 16.0 17.3 9.0 12.3
10.0 13.0 12.7 14.0 11.0 12.0 7.0 7.0 7.0 7.3 12.0 12.3 11.3 11.7 13.7 14.0 15.0 17.0 12.7 13.0
11.0 13.7 13.0 15.7 11.0 12.3 7.3 7.3 11.0 12.0 13.0 13.0 13.7 13.7 14.0 14.3 15.7 17.7 13.0 13.3
10.3 10.0 10.3 8.0 11.0 10.3 10.3 8.0 10.0 9.3 9.7 8.0 12.7 10.0 10.3 10.0 10.3 10.0 10.3 9.7 12.0 11.0 11.3 10.7 7.0 9.0 6.7 6.7 9.3 7.0 6.7 7.3 7.3 11.0 12.0 10.7 7.7 12.0 12.3 11.0 8.7 11.7 9.7 10.0 13.0 10.0 10.3 9.7 11.0 10.7 14.0 10.0 11.3 21.7 23.0 20.7 12.7 10.0 10.3 18.7 14.0 11.0 11.0 9.7 15.0 9.0 9.7 8.0 16.3 9.7 10.0 8.3 9.0 11.0 8.7 7.0 9.3 8.7 12.7 9.0
A 106 cell/ml B 103 celliml
against S. aureus was also reported by RACCACH et al. [20]. The extent of inhibition of microorganisms by lactic culture varies depending on the strain and other factors. We observed that, among the lactic culture L . casei had the greatest antimicrobial activity, whereas Leu. mesenteroides weakly inhibited growth of tested bacteria. Other lactic culture showed varying degrees of antimicrobial activity. PULUSANI et al. [17] reported that S. lactis weakly inhibited the growth of the P . aeroginosa and B. subtilis. Growth of Enterobacter cloacae and E. aerogenes was markedly inhibited by S. lactis and S. crernoris [24]. The antimicrobial activity of Leu. rnesenteroides and L . casei was not reported in the literature previously. In general, inoculum density had little effect on inhibition. The antimicrobial activity of cell-free filtrate from lactic cultures was generally greater against the gram negative than the gram positive organisms tested. These observations agree with those of other investigators [8,23]. However, GILLIAND et al. [l 11 reported that the gram positive bacteria were more sensitive to the inhibitory action of L . acidophilus than were the gram negative species, contrary to our results. It may be due to differences in the nature of strains or the type of suspending medium. Antimicrobial activity of lactic culture was maximum after 48 h of incubation and the activity dropped upon further incubation. This observation confirms an earlier report [5, 181. RAOet al. [18] reported that antimicrobial activity of S. therrnophilus grown in whole milk at 50 "C was maximum after 48 h of incubation. Inhibitory activity of various lactic cultures [4, 20-221 against the spoilage bacteria in foods apparently is due to the metabolites released by the lactic cultures, as has been suggested previously by GILLIAND et al. [12].
276
Die Nahrung 34 (1990) 3
Results of this investigation indicate that antimicrobial compound(s) are produced by lactic cultures. Apparently the antimicrobial substances are metabolites of lactic cultures rather than structural components of the lactic cultures. Therefore, the use of these organisms appears to have great potential for controlling the growth of food spoilage and pathogenic microorganisms in food. Zusammenfassung MERIHKIVANC : Antagonistische Wirkung von Milchsaurekulturen gegenuber Verderb hervorrufenden und pathogen wirkenden Mikroorganismen in Nahrungsmitteln Die antibakteriellen Eigenschaften zellfreier Filtrate von Milchsaurekulturen werden gegenuber 10 Bakterienkulturen gepriift. Alle 5 Species der gepriiften Milchsaurekulturen zeigen antimikrobielle Aktivitat gegenuber den getesteten Bakterh. S.aureus wird am wenigsten beeinflu& gefolgt von E. coli und S. typhosa. E. aerogenes erweist sich als am empfindlichsten. L. casei zeigt die hochste antimikrobielle Aktivitat. Leu. mesenteroides hemmt das Wachstum der gepriiften Bakterien nur schwach. Die Inokulum-Dichte hat im allgemeinen nur wenig EinfluD auf die Hemmung. Pem~e
References [l] ABDEL-BAR, N . M., and N. D. HARRIS,J. Food Protect. 47, 61-64 (1984). [2] ANGELO,I. A., K. M. SHAHANI and A. D. AYELO,J. Dairy Sci. 63 (Supplement), 52,(1980). [3] BABEL,F. J., J. Dairy Sci. 60,815-821 (1977). [4] BGTEPE,S. Bazi sut mamullerinden ayrilan koagulaz-pazitif Stafilococcus’ lar ve bunlafin gelismeleri iizerine siit asidi bakterilerinin etkisi (Doktora Tezi) Ankara. [5] BRANEN, A. L., H. C. Go and R. P. GENSKE,J. Food Sci. 40,446-450 (1975). [6] DALY,C., W. E. SANDINE and P. R. ELLIKER, J. Milk Food Technol. 35, 349-357 (1972). [7] EL-KHATBLB, T., and H. A. EL-RAHMAN, J. Food Protect. 50, 310-311 (1987). [8] GENSKE, R. P., and A. L. BRANEN, Modern Dairy 52, 12-14 (1973). [9] GILLILAND, S. E., and M. L. SPECK,J. Milk Food Technol. 35, 307-310 (1972). [lo] GILLILAND, S. E., and M. L. SPECK,J. Food Sci. 40, 903-905 (1975). [ l l ] GILLILAND, S. E., and M. L. SPECK,J. Food Prot. 40, 820-823 (1977). [I21 KEOGH,B. P., J. Dairy Res. 38, 91-111 (1971). [13] MARTIN,D. R., and S. E. GILLIAND, J. Food Protect. 43, 675-678 (1980). [I41 PAMIR,H., Fermentation microbiology (in Turkish), Ankara Univ. Fac. Agric. Publ. No. 936, Ankara 1985. [I51 PARK,H. S., and E. H. MARTH,J. Milk Food Technol. 35, 482-483 (1972). [I61 PRICE,R. J., and J. S. LEE.J. Milk Food Technol. 33, 13-18 (1970). S. R., D. R. RAOand G. R. SUNKI,J. Food Sci. 44,575-578 (1979). [17] PULUSANI, [18] RAO,D. R., and S. R. PULUSANI, J. Food Sci. 46,630-632 (1981).
KIVANG: Action of lactic cultures
277
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