Inhibitory Effect of Lactobacillus bulgaricus on Psychrotrophic Bacteria in Associative Cultures and in Refrigerated Foods

1984 ◽  
Vol 47 (1) ◽  
pp. 61-64 ◽  
Author(s):  
NADIA M. ABDEL-BAR ◽  
NATHOLYN D. HARRIS
Keyword(s):  
Growth Inhibition ◽  
Inhibitory Effect ◽  
Lactobacillus Bulgaricus ◽  
Pseudomonas Fragi ◽  
Psychrotrophic Bacteria ◽  
The Third ◽  
Control Growth ◽  
Natural Flora ◽  
Test Organisms ◽  
Total Growth

The purposes of this study were two-fold: (a) to determine growth inhibition of Pseudomonas fragi, Achromobacter liquefaciens and Staphylococcus aureus due to Lactobacillus bulgaricus in associative cultures, and (b) to evaluate use of L. bulgaricus to control growth of natural flora in refrigerated tuna and potato salads and ground beef. The antagonistic effects of three concentrations of L. bulgaricus were studied after storage for 5 d at 6°C. Data were analyzed using a Student t Test. Pronounced inhibition was observed toward test organisms. Total growth inhibition of P. fragi and A. liquefaciens was attained due to the third level of L. bulgaricus (1.4 × 106 − 5.7 × 106 cells/ml). Natural flora in test foods were also greatly inhibited. Total growth inhibition of bacteria was attained in potato salad due to the third level of L. bulgaricus (3.9 × 106 cells/g). It was suggested that organic acids and hydrogen peroxide were partially responsible for the inhibition.

The Automated Pyruvate Method as a Quality Test for Grade A Milk

1978 ◽  
Vol 41 (3) ◽  
pp. 168-177 ◽  
Author(s):  
R. T. MARSHALL ◽  
C. C. HARMON
Keyword(s):  
Incubation Temperature ◽  
Micrococcus Luteus ◽  
Raw Milk ◽  
Salmonella Typhi ◽  
Pseudomonas Fragi ◽  
Pasteurized Milk ◽  
Psychrotrophic Bacteria ◽  
Natural Flora ◽  
Pure Cultures ◽  
Plate Counts

Concentrations of pyruvate in Grade A raw and pasteurized milks were determined by an automated procedure. The method was sensitive to 0.1 mg of pyruvate per liter and the coefficient of variation of the method was 1.6% for a sample of milk containing 3 mg/1. Since about twice as much pyruvate was produced in samples incubated 24 h at 20 C compared with 15 C, the higher temperature is suggested for the pyruvate difference test (ΔP); however, psychrotrophs would more likely be detected with an incubation temperature of 15 C. Pyruvate difference tests of pure cultures in steamed milk distinguished between concentrations approximating 102 and 103 Pseudomonas fragi, 103 and 104 Pseudomonas fluorescens, and between 104 and 105 Escherichia coli, Streptococcus faecalis, Lactobacillus acidophilus and Micrococcus luteus, but did not distinguish between 104 and 105 initial concentrations of six other gram-positive bacteria and Salmonella typhi. Both the initial pyruvate (IP) concentration and the ΔP in raw milk were correlated with the logarithm of the Wisconsin Mastitis Test score, suggesting that somatic cells contribute to pyruvate content. Correlations of IP and ΔP with Standard Plate Counts of raw and pasteurized milks were low or insignificant and only with raw milk from normal quarters was there a significant correlation of IP and ΔP with initial Psychrotrophic Plate Counts (PPC). Rates of pyruvate production by pure cultures in steamed milk and by the mixed natural flora of pasteurized milk were consistent with rates of growth. However, certain psychrotrophic bacteria reduced the concentration of pyruvate to undetectable levels after producing 10 or more mg/1. Suggestions are made regarding applicability of the test in controlling keeping quality of pasteurized milk and in receiving of bulk raw milk.

Antibacterial Activity of Yogurt Starter in Cow and Buffalo Milk

1979 ◽  
Vol 42 (8) ◽  
pp. 664-665 ◽  
Author(s):  
JASJIT SINGH ◽  
ADARSH KHANNA ◽  
BARISH CHANDER
Keyword(s):  
Antibacterial Activity ◽  
Streptococcus Thermophilus ◽  
Buffalo Milk ◽  
Comparative Assessment ◽  
Lactobacillus Bulgaricus ◽  
Cow Milk ◽  
Antagonistic Action ◽  
Pseudomonas Fragi ◽  
Test Organisms ◽  
Pronounced Inhibition

A comparative assessment of the antibacterial activity of pure and mixed-strain cultures of Streptococcus thermophilus and Lactobacillus bulgaricus against Escherichia coli. Staphylococcus aureus, Pseudomonas fragi and Micrococcus flavus was made using cow and buffalo milk. A culture filtrate from S. thermophilus exhibited no antagonistic action against any of the test organisms, irrespective of the type of milk used and the period of incubation. Culture filtrates from L. bulgaricus and the mixed culture caused pronounced inhibition of all the test organisms used. Antibacterial activity of yogurt culture was greater in buffalo than cow milk.

Inhibition of Psychrotrophic Bacteria in Refrigerated Milk by Lactobacilli Isolated from Yogurt1

1980 ◽  
Vol 43 (9) ◽  
pp. 675-678 ◽  
Author(s):  
D. R. MARTIN ◽  
S. E. GILLILAND
Keyword(s):  
Hydrogen Peroxide ◽  
Agar Medium ◽  
Raw Milk ◽  
Inhibitory Effect ◽  
Significant Inhibition ◽  
Lactobacillus Bulgaricus ◽  
C Cells ◽  
Psychrotrophic Bacteria ◽  
Colored Zone

A “milk-peroxidase” agar was prepared to select cultures of lactobacilli that most actively produce hydrogen peroxide. O-tolidine and peroxidase contained in the medium reacted with hydrogen peroxide produced by the bacteria to form a colored zone around the colonies during their formation on the agar at 37 C. There appeared to be no relationship between the size of zones surrounding the colonies on the agar medium and the amount of peroxide produced in milk at 5.5 C. Cells from frozen concentrated cultures of selected lactobacilli were added to milk to achieve desired populations in the interaction experiments. A significant inhibition of a psychrotrophic culture in autoclaved milk at 5.5 C occurred when at least 2.5 × 107 lactobacilli were added per ml. Larger numbers of lactobacilli resulted in greater inhibition of the psychrotroph. The intensity of inhibition of a psychrotrophic culture in autoclaved milk varied among the cultures of lactobacilli tested. In most instances, the more active inhibitory cultures produced more peroxide in refrigerated milk than less inhibitory ones. In preliminary experiments, a culture of Lactobacillus bulgaricus selected by the above procedure produced no inhibitory effect against the growth of psychrotrophic bacteria in non-agitated raw milk at 5.5 C.

Growth Inhibition of Microorganisms in Refrigerated Milk by added Maillard Reaction Products1

1985 ◽  
Vol 48 (2) ◽  
pp. 138-141 ◽  
Author(s):  
ROSA C. DE LARA ◽  
S. E. GILLILAND
Keyword(s):  
Growth Inhibition ◽  
Maillard Reaction ◽  
Raw Milk ◽  
Bactericidal Effect ◽  
Refrigerated Storage ◽  
Pseudomonas Fragi ◽  
Nonfat Milk ◽  
Natural Flora ◽  
Micro Organisms ◽  
Milk Solids

Maillard Reaction Product (MRP) prepared by heating (2 h at 121°C) a solution of 0.2 M glucose and 0.2 M histidine was added at different concentrations (0.23, 0.47 and 0.70%) to cold milk (either autoclaved reconstituted 10% nonfat milk solids inoculated with Pseudomonas fragi or raw milk) and stored at 5°C to evaluate its effect on growth of psychrotrophic microorganisms during refrigerated storage. Growth of micro-organisms decreased as the percentage MRP increased. P. fragi in autoclaved nonfat milk was inhibited more than was the natural flora in raw milk. An apparent bactericidal effect was observed at higher MRP concentration in autoclaved milk; however, this was not evident for raw milk.

scholarly journals Anti-trypanosomal activity of pentacyclic triterpenes isolated from Austroplenckia populnea (Celastraceae)

2002 ◽  
Vol 44 (2) ◽  
pp. 109-112 ◽  
Author(s):  
Lucienir Pains DUARTE ◽  
Sidney Augusto VIEIRA FILHO ◽  
Grácia Divina de Fátima SILVA ◽  
José Rego de SOUSA ◽  
Artur da Silveira PINTO
Keyword(s):  
Growth Inhibition ◽  
High Activity ◽  
Incubation Time ◽  
Inhibitory Effect ◽  
Suitable Model ◽  
Pentacyclic Triterpenes ◽  
Total Growth ◽  
Dose Dependent

Four pentacyclic triterpenes isolated from Austroplenckia populnea and four compounds of known anti T. cruzi or anti-malarial activity were tested. Of those triterpenes tested 20alpha-hydroxy-tingenone showed high activity, epikatonic acid was less active, while populnilic and populninic acids were inactive against the trypanosome of the subgenus Schizotrypanum tested. Benzonidazole, nifurtimox, ketoconazole and primaquine presented a remarkable dose-dependent inhibitory effect reaching practically to a total growth inhibition of the parasite at the end of incubation time. The trypanosome tested appear to be a suitable model for preliminary screen for anti T. (S.) cruzi compounds.

scholarly journals Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽  
1990 ◽  
Vol 76 (6) ◽  
pp. 1250-1255 ◽  
Author(s):  
S Whitehead ◽  
TE Peto
Keyword(s):  
Plasmodium Falciparum ◽  
Growth Inhibition ◽  
Antimalarial Activity ◽  
Clinical Malaria ◽  
Inhibitory Effect ◽  
Parasite Development ◽  
And Control ◽  
Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

SYNTHESIS AND ANTICANCER ACTIVITY EVALUATION OF SOME SCHIFF BASES OF 1, 3, 4-OXADIAZOLE

INDIAN DRUGS ◽  
2019 ◽  
Vol 56 (03) ◽  
pp. 12-17
Author(s):  
Manpreet Kaur ◽  
S. Singh ◽  
Keyword(s):  
Schiff Base ◽  
Growth Inhibition ◽  
Anticancer Activity ◽  
Maximum Growth ◽  
Schiff Base Derivatives ◽  
Control Growth ◽  
Anti Cancer ◽  
Oxadiazole Derivatives ◽  
Cancer Activity ◽  
Mcf 7

A new series of 2,5-disubstituted-1,3,4-oxadiazole derivatives has been synthesized with the help of different aromatic benzaldehydes and final compounds were characterized by FTIR and 1H NMR. 2,5- disubstituted-1,3,4-oxadiazole derivatives were synthesized by the reaction of Schiff base derivatives with 2,5-disubstituted-1,3,4-oxadiazoles. All the synthesized compounds were screened for their anticancer activity. These compounds were evaluated for their anticancer activity against various cancer cell lines. Five of the compounds possessed good to moderate anti-cancer activity. Three of the synthesized compounds i.e. 6a, 6f and 6g were found to possess maximum growth inhibition. The order for the % control growth inhibition of MCF-7 was found to be 6a>6f>6g>5b>6h, as shown in Table II-VI.

Bioaerosol Exposure Method for Package Integrity Testing†

1996 ◽  
Vol 59 (7) ◽  
pp. 768-771 ◽  
Author(s):  
SCOTT W. KELLER ◽  
JOSEPH E. MARCY ◽  
BARBARA A. BLAKISTONE ◽  
GEORGE H. LACY ◽  
CAMERON R. HACKNEY ◽  
...  
Keyword(s):  
Particle Size ◽  
Test Organism ◽  
Hole Diameter ◽  
Pseudomonas Fragi ◽  
Integrity Testing ◽  
Aerosol Exposure ◽  
Exposure Method ◽  
Test Organisms ◽  
Organism Growth ◽  
Bioaerosol Exposure

Test organism motility, concentration, aerosol exposure time, hole diameter and length were evaluated to determine their influence on microbial ingress into a flexible plastic pouch. Microtubes with 10- and 20-μm hole diameters and of 5- and 10-mm lengths were used as defects in 128 flexible pouches. A bioaerosol with a 2.68-μm mean particle size comprised of 102 or 106 CFU/ml source concentrations of motile or nonmotile Pseudomonas fragi TM 849 was introduced into a 119,911-cm3 chamber for exposures of 15 or 30 minutes. Six pouches showed test organism growth after a 72-h incubation period. Microbial ingress was significant (P < .05) for motile test organisms with source concentrations of 106 CFU/ml.

Effect of Ozone on the Inactivation of Yersinia enterocolitica and the Reduction of Natural Flora on Potatoes

2006 ◽  
Vol 69 (10) ◽  
pp. 2357-2363 ◽  
Author(s):  
MARÍA VICTORIA SELMA ◽  
DAVID BELTRÁN ◽  
ELISEO CHACÓN-VERA ◽  
MARÍA ISABEL GIL
Keyword(s):  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Disease Outbreaks ◽  
Wash Water ◽  
Foodborne Disease ◽  
Pathogenic Microorganisms ◽  
Psychrotrophic Bacteria ◽  
Fresh Vegetables ◽  
Natural Flora ◽  
Soil Irrigation

Fresh vegetables contaminated with Yersinia enterocolitica have been implicated in foodborne disease outbreaks. Surfaces of vegetables can become contaminated with pathogenic microorganisms through contact with soil, irrigation water, fertilizers, equipment, humans, and animals. One approach to reduce this contamination is to treat fresh produce with sanitizers. In this study, the ability of ozone to inactivate Y. enterocolitica inoculated in water and on potato surfaces was evaluated. Furthermore, the efficacy of ozone in reducing natural flora on whole potato was determined. Total aerobic mesophilic and psychrotrophic bacteria, total coliforms, and Listeria monocytogenes were enumerated. Finally, several disinfection kinetic models were considered to predict Y. enterocolitica inactivation with ozone. Treatments with ozone (1.4 and 1.9 ppm) for 1 min decreased the Y. enterocolitica population in water by 4.6 and 6.2 log CFU ml−1, respectively. Furthermore, ozonated water (5 ppm) for 1 min decreased Y. enterocolitica and L. monocytogenes from potato surfaces by 1.6 and 0.8 log CFU g−1, respectively. Therefore, ozone can be an effective treatment for disinfection of wash water and for reduction of potato surface contamination.

Yeasts as Primary Contaminants in Yogurts Produced Commercially in Lagos, Nigeria

1987 ◽  
Vol 50 (3) ◽  
pp. 193-198 ◽  
Author(s):  
MINABELEMA DUBLIN GREEN ◽  
STELLA N. IBE
Keyword(s):  
Streptococcus Thermophilus ◽  
Maximum Growth ◽  
Starter Cultures ◽  
Lactobacillus Bulgaricus ◽  
Contamination Level ◽  
Psychrotrophic Bacteria ◽  
Retail Outlets ◽  
Candida Lusitaniae ◽  
Aspergillus Sp ◽  
Initial Contamination

Yogurt samples purchased from a dairy industry, retail outlets, and hawkers in Lagos, Nigeria, were plated on potato dextrose agar containing 100 μg of chloramphenicol/ml and found to contain Candida lusitaniae, C krusei, C rugosa, Kluveromyces fragilis, and Saccharomyces cerevisiae as the primary yeast contaminants. Sixty-seven percent of the samples had yeast counts in the range of 104–106 cfu/ml. C. lusitaniae, K. fragilis and C. krusei had the highest counts and occurrence of 65, 48 and 51%, respectively, in 100 random yogurt samples. C. lusitaniae attained the highest count in yogurts stored at 10°C and C. krusei in those at 30°C. Ninety percent of the samples had less than 10 coliforms or staphylococci per ml, whereas 20% had over 103 psychrotrophic bacteria per ml. Molds of Aspergillus sp. and Neurospora sp. were isolated mainly from the strawberry-fluid yogurt. The starter cultures, Lactobacillus bulgaricus and Streptococcus thermophilus, were present in the ratio of 1:1 and reached maximum growth levels of 107 to 108 cfu/ml after 4 to 8 d of storage at 10°C, whereas the yeast continued to increase beyond this level by the 12th day. The extent of contamination observed suggests high initial contamination level and improper refrigeration of yogurts marketed.

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