scholarly journals Genetic characterization of the microbiota of artisan fresh cheese from the Papaloapan region

2021 ◽  
Vol 6 (2) ◽  
pp. 61-85
Author(s):  
Miguel A. García-Muñoz ◽  
◽  
Nancy Cruz-Velazco ◽  
América Chávez-Martínez ◽  
Cirilo Nolasco-Hipólito ◽  
...  

The population of the Papaloapan region consume artisan fresh cheeses and no pathogen outbreaks have been reported recently. The microbiota is responsible to develop desirable characteristics of cheeses and undesirable characteristics due to the presence of certain pathogens microorganisms. Therefore, to identify the microorganisms of fresh cheeses is an important issue for the producers, consumers, and authorities. 11 Artisan fresh cheese samples from the Papaloapan region were collected in the summer and 11 samples in winter to characterize their microbiota. Traditional microbial techniques were used to identify the fungus and the amplification of the 16S rRNA gene and PCR-denaturing gradient gel electrophoresis (DGGE) The population of the Papaloapan region consume artisan fresh cheeses and no pathogen outbreaks have been reported recently. The microbiota is responsible to develop desirable characteristics of cheeses and undesirable characteristics due to the presence of certain pathogens microorganisms. Therefore, to identify the microorganisms of fresh cheeses is an important issue for the producers, consumers, and authorities. 11 Artisan fresh cheese samples from the Papaloapan region were collected in the summer and 11 samples in winter to characterize their microbiota. Traditional microbial techniques were used to identify the fungus and the amplification of the 16S rRNA gene and PCR-denaturing gradient gel electrophoresis (DGGE) The population of the Papaloapan region consume artisan fresh cheeses and no pathogen outbreaks have been reported recently. The microbiota is responsible to develop desirable characteristics of cheeses and undesirable characteristics due to the presence of certain pathogens microorganisms. Therefore, to identify the microorganisms of fresh cheeses is an important issue for the producers, consumers, and authorities. 11 Artisan fresh cheese samples from the Papaloapan region were collected in the summer and 11 samples in winter to characterize their microbiota. Traditional microbial techniques were used to identify the fungus and the amplification of the 16S rRNA gene and PCR-denaturing gradient gel electrophoresis (DGGE) method was used for bacteria identification. For all the samples, the presence of aerobic mesophiles, Streptococcus mesophiles and thermophiles, Lactobacillus mesophiles, Leuconostoc, total coliforms, Staphylococcus aureus, molds, and yeasts were identified. The complexity and variety of microorganisms in the summer and winter seasons samples were not significantly different. In conclusion, all samples of fresh artisan cheeses were under high microbial loads. Lactic Acid Bacteria (LAB) were in a typical load, as established by the quality and safety standards in the food industry. Conversely, pathogenic bacteria exceeded this limit. The microorganisms present in the fresh artisanal cheeses of the Papaloapan region were identified with precision, regarding the count and their diversity. A recommendation for the cheese manufacturers is to prepare starter cultures by selecting the appropriate microorganisms to produce the desirable characteristics such as aroma and flavor and reduce the risk of microbial infections by using pasteurized milk.

2005 ◽  
Vol 71 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Anne-Ga�lle Le Bourhis ◽  
Katiana Saunier ◽  
Jo�l Dor� ◽  
Jean-Philippe Carlier ◽  
Jean-Fran�ois Chamba ◽  
...  

ABSTRACT A nested-PCR temporal temperature gradient gel electrophoresis (TTGE) approach was developed for the detection of bacteria belonging to phylogenetic cluster I of the genus Clostridium (the largest clostridial group, which represents 25% of the currently cultured clostridial species) in cheese suspected of late blowing. Primers were designed based on the 16S rRNA gene sequence, and the specificity was confirmed in PCRs performed with DNAs from cluster I and non-cluster I species as the templates. TTGE profiles of the PCR products, comprising the V5-V6 region of the 16S rRNA gene, allowed us to distinguish the majority of cluster I species. PCR-TTGE was applied to analyze commercial cheeses with defects. All cheeses gave a signal after nested PCR, and on the basis of band comigration with TTGE profiles of reference strains, all the bands could be assigned to a clostridial species. The direct identification of Clostridium spp. was confirmed by sequencing of excised bands. C. tyrobutyricum and C. beijerinckii contaminated 15 and 14 of the 20 cheese samples tested, respectively, and C. butyricum and C. sporogenes were detected in one cheese sample. Most-probable-number counts and volatile fatty acid were determined for comparison purposes. Results obtained were in agreement, but only two species, C. tyrobutyricum and C. sporogenes, could be isolated by the plating method. In all cheeses with a high amount of butyric acid (>100 mg/100 g), the presence of C. tyrobutyricum DNA was confirmed by PCR-TTGE, suggesting the involvement of this species in butyric acid fermentation. These results demonstrated the efficacy of the PCR-TTGE method to identify Clostridium in cheeses. The sensitivity of the method was estimated to be 100 CFU/g.


2004 ◽  
Vol 70 (11) ◽  
pp. 6920-6926 ◽  
Author(s):  
Laura Villanueva ◽  
Antoni Navarrete ◽  
Jordi Urmeneta ◽  
David C. White ◽  
Ricardo Guerrero

ABSTRACT A combined lipid biomarker-16S rRNA gene denaturing gradient gel electrophoresis analysis was used to monitor changes in the physiological status, biomass, and microbial composition of a microbial mat. In the morning hours, an increase in the biomass of layers containing a high density of phototrophs and a decrease in the growth rate in the deep layers were observed. The combined approach also revealed differences in major groups of microorganisms, including green nonsulfur, gram-positive, and heterotrophic bacteria.


2013 ◽  
Vol 726-731 ◽  
pp. 3680-3684
Author(s):  
Ying Zhang ◽  
Cheng You Cao ◽  
Peng Zhang

The purpose of this study is to assess the application of denaturing gradient gel electrophoresis (DGGE) for analyzing the bacterial and cyanobacterial diversities of biological soil crusts (BSCs) in sandy land. Soil microbial DNA was extracted from BSCs under different plantations in Horqin Sandy Land of Northeast China. 16S rRNA gene fragments from bacteria and cyanobacteria were amplified by universal bacterial and cyanobacteria-specific primers. Fourteen and six prominent bands were detected in the bacterial and cyanobacterial DGGE profiles, respectively. These bands were excised, cloned and sequenced. Phylogenetic analysis classified the bacterial sequences into the following main groups:Escherichia,Bacillus,Paenibacillus,Shigella, andPseudomonas. The cyanobacterial sequences were classified asMicrocoleus,LeptolyngbyaandHaslea. Our study suggests that DGGE is a useful technique for detecting dominant species compositions of bacterial and cyanobacterial communities in biological soil crusts, and specific primers are recommended for PCR of 16S rRNA gene fragments.


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