El objetivo del presente trabajo fue evaluar el efecto de la deshidratación de los lodos en lecho de secado sobre las características fisicoquímicas de estos subproductos y la actividad biológica de los microorganismos. Se determinó que después de cinco meses de secado disminuyó la concentración de carbono orgánico, los metales pesados se mantuvieron por debajo del límite permisible y el nitrógeno y fósforo total se mantuvieron constantes. Se evidenció disminución de los aerobios mesófilos, hongos y amilolíticos de siete, seis y una unidad logarítmica de UFC/g respectivamente. La presencia de microorganismos funcionales celulolíticos y solubilizadores de fosfato fue <10 UFC/g. Por otro lado, el 3 % (n=8040) de las cepas evaluadas, fueron productoras de PHA en por lo menos una de las fuentes de carbono evaluadas (sacarosa o glucosa). Los resultados demuestran que el tratamiento de deshidratación en lecho de secado permitió conservar las características fisicoquímicas de los lodos, no obstante, disminuyó la actividad biológica de los microrganismos aerobios mesófilos, amilolíticos y hongos, celulolíticos, solubilizadores de fosfato.
Background: Paipa cheese is a traditional, semi-ripened cheese made from raw cow’s milk in Colombia. The aim of this work was to gain insights on the microbiota of Paipa cheese by using a culture-independent approach. Method: two batches of Paipa cheese from three formal producers were sampled during ripening for 28 days. Total DNA from the cheese samples was used to obtain 16S rRNA gene sequences by using Illumina technology. Results: Firmicutes was the main phylum found in the cheeses (relative abundances: 59.2–82.0%), followed by Proteobacteria, Actinobacteria and Bacteroidetes. Lactococcus was the main genus, but other lactic acid bacteria (Enterococcus, Leuconostoc and Streptococcus) were also detected. Stapylococcus was also relevant in some cheese samples. The most important Proteobacteria were Enterobacteriaceae, Aeromonadaceae and Moraxellaceae. Enterobacter and Enterobacteriaceae (others) were detected in all cheese samples. Serratia and Citrobacter were detected in some samples. Aeromonas and Acinetobacter were also relevant. Other minor genera detected were Marinomonas, Corynebacterium 1 and Chryseobacterium. The principal coordinates analysis suggested that there were producer-dependent differences in the microbiota of Paipa cheeses. Conclusions: lactic acid bacteria are the main bacterial group in Paipa cheeses. However, other bacterial groups, including spoilage bacteria, potentially toxin producers, and bacteria potentially pathogenic to humans and/or prone to carry antimicrobial resistance genes are also relevant in the cheeses.
The objective of this work was to evaluate the microbiological quality of cheese produced by formal and informal microenterprises in Paipa, Colombia, to isolate potentially pathogenic bacteria and to determine their prevalence and resistance to antimicrobials such as antibiotics and biocides. Sixteen micro-enterprises of the seventy existing in the region were sampled during 3 years. Viable concentrations of aerobic mesophiles, total and fecal coliforms, Salmonella sp., Listeria monocytogenes, Staphylococcus sp., yeasts, and molds were determined. Seventy-three bacterial isolates were identified by 16S rRNA gene sequencing. The susceptibility of the isolates to antibiotics and biocides was determined. The results indicated that between 98 and 100% of the cheese samples (n = 48 samples) of formal and informal micro-enterprises presented populations of total and fecal coliforms and Staphylococcus sp. above the limits established by Colombian regulations and varied according to the micro-enterprise. The results also indicated that 56% of Staphylococcus isolates were S. aureus. L. monocytogenes was positive in 38% of the samples. Salmonella sp. was not detected. The coliforms that prevailed were Escherichia coli (25%), Citrobacter freundii (14%), and Proteus mirabilis (8%). All L. monocytogenes were sensitive to ampicillin but resistant to erythromycin and trimethoprim-sulfamethoxazole. S. aureus isolates were susceptible to most antibiotics, except tetracycline and erythromycin (7% resistance). Likewise, 30% of coliforms (n = 36) were multidrug-resistant to antibiotics but susceptible to biocides.
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