ABSTRACT
We investigated the chemical and microbiological compositions of three types of whey to be used for kefir fermentation as well as the inhibitory capacity of their subsequent fermentation products against 100 Salmonella sp. and 100 Escherichia coli pathogenic isolates. All the wheys after fermentation with 10% (wt/vol) kefir grains showed inhibition against all 200 isolates. The content of lactic acid bacteria in fermented whey ranged from 1.04 × 10(7) to 1.17 × 10(7) CFU/ml and the level of yeasts from 2.05 × 10(6) to 4.23 × 10(6) CFU/ml. The main changes in the chemical composition during fermentation were a decrease in lactose content by 41 to 48% along with a corresponding lactic acid production to a final level of 0.84 to 1.20% of the total reaction products. The MIC was a 30% dilution of the fermentation products for most of the isolates, while the MBC varied between 40 and 70%, depending on the isolate. The pathogenic isolates Salmonella enterica serovar Enteritidis 2713 and E. coli 2710 in the fermented whey lost their viability after 2 to 7 h of incubation. When pathogens were deliberately inoculated into whey before fermentation, the CFU were reduced by 2 log cycles for E. coli and 4 log cycles for Salmonella sp. after 24 h of incubation. The inhibition was mainly related to lactic acid production. This work demonstrated the possibility of using kefir grains to ferment an industrial by-product in order to obtain a natural acidic preparation with strong bacterial inhibitory properties that also contains potentially probiotic microorganisms.
Subject(s)
Cultured Milk Products/microbiology , Escherichia coli/drug effects , Food Microbiology , Milk Proteins/pharmacology , Salmonella/drug effects , Cheese/microbiology , Colony Count, Microbial , Consumer Product Safety , Escherichia coli/growth & development , Fermentation , Food Contamination/analysis , Food Contamination/prevention & control , Humans , Probiotics , Salmonella/growth & development , Whey ProteinsABSTRACT
The circadian rhythm of alpha-amylase, E.C. 3.2.1.1. alpha-1,4-glucan-4-glucanohydrolase) in the parotid glands of 25-day-old rats were studied under different experimental designs (fasting, reversed photoperiod, constant lighting conditions and treatment with reserpine and alpha-methyl-p-tyrosine). The rhythm of fasted rats did not change. There were modifications in the rhythm of rats submitted to a reversed photoperiod or treated with reserpine or alpha-methyl-p-tyrosine. The rhythm was present, with changes in the acrophase, in parotids of rats kept during their gestation and postnatal life in constant light or dark. Results suggest that the circadian rhythm of alpha-amylase in parotid gland of young rats is endogenous, synchronized by the photoperiod, and with maternal coordination.
Subject(s)
Aging/physiology , Circadian Rhythm/physiology , Parotid Gland/enzymology , alpha-Amylases/physiology , Aging/drug effects , Aging/radiation effects , Animals , Circadian Rhythm/drug effects , Circadian Rhythm/radiation effects , Female , Food Deprivation/physiology , Light , Male , Methyltyrosines/pharmacology , Parotid Gland/drug effects , Parotid Gland/radiation effects , Pregnancy , Prenatal Exposure Delayed Effects , Rats , Rats, Inbred Strains , Reserpine/pharmacology , alpha-Amylases/drug effects , alpha-Amylases/radiation effects , alpha-MethyltyrosineABSTRACT
Starch gel electrophoretic zymograms were used for the taxonomic separation of mosquitoes of the genus Culex, possible vectors of encephalitis in Argentina. Catalase, hexokinase, malic enzyme, isocitrate and malate dehydrogenases, and leucine aminopeptidase were species markers that allowed the clear identification of individual Culex apicinus Philippi, Cx. bidens Dyar, Cx. brethesi Dyar, Cx. declarator Dyar and Knab, Cx. dolosus Arribalzaga, Cx. maxi Dyar, Cx. quinquefasciatus Say, Cx. saltanensis Dyar, and Cx. tatoi Casal & García. Intraspecific polymorphism was revealed but did not preclude species separation. On the basis of allele frequencies, an index of genetic distance between species was calculated. Genetic affinities determined by electrophoretic data agreed with taxonomic affinities ascertained by conventional systematics. Thus, electrophoretic zymograms proved to be a powerful tool for the study of the genus Culex in Argentina.
Subject(s)
Culex/classification , Insect Vectors/classification , Alleles , Animals , Argentina , Culex/genetics , Electrophoresis, Starch Gel , Female , Insect Vectors/genetics , MaleABSTRACT
The circadian rhythm of alpha-amylase, E.C. 3.2.1.1. (alpha-1,4-glucan-4-glucanohydrolase) in parotid gland of 25 day old rats was studied under different experimental conditions (fast, reversed photoperiod, constant light or darkness and treatment with reserpine and alpha-methyl-p-tyrosine). The rhythm of rats fasted or exposed for 7 days to constant darkness did not change. There were modifications in the rhythm of rats submitted to a reversed photoperiod and it disappeared in animals submitted to constant light or darkness for 15 days or treated with reserpine or alpha-methyl-p-tyrosine. The rhythm persisted, with minor changes in the acrophase, in parotids of rats kept during their gestation and post-natal life in constant light or darkness. Results suggest that the circadian rhythm of alpha-amylase in parotid gland of young rats is endogenous, synchronized by the photoperiod, under autonomous nervous system control and maternal coordination. This model appears to be useful in the study of sympathetic nervous system control of target organs and circadian rhythms in general.
Subject(s)
Parotid Gland/enzymology , alpha-Amylases/metabolism , Age Factors , Animals , Circadian Rhythm , Fasting , Light , Male , Methyltyrosines/pharmacology , Rats , Rats, Inbred Strains , Regression Analysis , Reserpine/pharmacology , Sympathetic Nervous System/physiology , alpha-MethyltyrosineABSTRACT
The circadian rhythm of alpha-amylase, E.C. 3.2.1.1. (alpha-1,4-glucan-4-glucanohydrolase) in parotid gland of 25 day old rats was studied under different experimental conditions (fast, reversed photoperiod, constant light or darkness and treatment with reserpine and alpha-methyl-p-tyrosine). The rhythm of rats fasted or exposed for 7 days to constant darkness did not change. There were modifications in the rhythm of rats submitted to a reversed photoperiod and it disappeared in animals submitted to constant light or darkness for 15 days or treated with reserpine or alpha-methyl-p-tyrosine. The rhythm persisted, with minor changes in the acrophase, in parotids of rats kept during their gestation and post-natal life in constant light or darkness. Results suggest that the circadian rhythm of alpha-amylase in parotid gland of young rats is endogenous, synchronized by the photoperiod, under autonomous nervous system control and maternal coordination. This model appears to be useful in the study of sympathetic nervous system control of target organs and circadian rhythms in general.
ABSTRACT
The circadian rhythm of alpha-amylase, E.C. 3.2.1.1. (alpha-1,4-glucan-4-glucanohydrolase) in parotid gland of 25 day old rats was studied under different experimental conditions (fast, reversed photoperiod, constant light or darkness and treatment with reserpine and alpha-methyl-p-tyrosine). The rhythm of rats fasted or exposed for 7 days to constant darkness did not change. There were modifications in the rhythm of rats submitted to a reversed photoperiod and it disappeared in animals submitted to constant light or darkness for 15 days or treated with reserpine or alpha-methyl-p-tyrosine. The rhythm persisted, with minor changes in the acrophase, in parotids of rats kept during their gestation and post-natal life in constant light or darkness. Results suggest that the circadian rhythm of alpha-amylase in parotid gland of young rats is endogenous, synchronized by the photoperiod, under autonomous nervous system control and maternal coordination. This model appears to be useful in the study of sympathetic nervous system control of target organs and circadian rhythms in general.