Few studies have screened fresh orange juice for the presence of foodborne pathogens. This study therefore evaluated the microbiological quality and occurrence of Salmonella, Shigella, Escherichia coli, and diarrheagenic E. coli pathotypes (DEP) in fresh-squeezed orange juice purchased from street vendors in Morelia, Michoacan, Mexico. The general hygienic practices of street vendors were poor. All 100 samples analyzed were positive for aerobic mesophilic bacteria, with concentrations ranging from 2.41 to 6.03 log CFU/mL. A total of 90 (90%), 35 (35%), and 14 (14%) samples were positive for total coliforms, fecal coliforms, and E. coli, respectively, present with concentrations ranging from < 1 to 4.84 log CFU/mL, < 3 to > 1,100 MPN/mL, and < 3 to 210 MPN/mL, respectively. Salmonella was not detected in any of the samples, whereas Shigella sonnei was isolated from one sample. Two samples were positive for DEP; one harbored ETEC strains and the other STEC strains. Our results highlight the elevated risk for consumer health associated with the ingestion of fresh-squeezed orange juice.

This study investigated the presence of nontuberculous mycobacteria (NTM) for the first time in two types of unpasteurized fresh cheese produced in the state of Michoacan, Mexico. We tested for this pathogen along with the others to broaden the study of microbiological quality in a total of 60 samples of cheese, 30 fresh and 30 adobera, which were collected from six artisanal cheese factories (ACF). The hygienic conditions of these establishments and the practices of cheese manufacture were generally poor. Although Mycobacterium bovis was not detected, four cheese samples harbored NTM isolates. The four NTM isolates were identified using three molecular markers (hsp65, rrs and rpoB genes) which corresponded to Mycolicibacterium fortuitum (n=3) and Mycolicibacterium mageritense (n=1). All 60 cheese samples analyzed had unsatisfactory microbiological quality according to the Mexican Official Guideline. Regarding fresh cheeses, all 30 samples analyzed were positive for aerobic mesophilic bacteria (AMB), total coliforms (TC), fecal coliforms (FC) and yeasts and moulds. Escherichia coli and Staphylococcus aureus were present in 23 and 21 samples, respectively. Listeria monocytogenes was identified in a sample and was isolated from a bulk milk tank in the same ACF. With regard to adobera cheeses, all samples were positive for AMB, TC, FC, yeasts and moulds and S. aureus. E. coli was isolated from 28 samples. Salmonella was isolated from a sample and also from a wooden shovel used in the manufacture of the cheeses in the same ACF. Thus, the consumption of unpasteurized fresh cheese may represent a public health risk. Because of this, health authorities should enforce the legislation that forbids the processing of cheese with unpasteurized milk and encourage producers to follow good manufacturing practices from original ingredients all the way through the production process of the cheese to its sale, in order to assure a safe product.

Streptomyces species have been successfully used in diverse biotechnological processes; however, little is known about actinobacterial biofilm formation and its use as a biofilmed inoculant. The present study assessed and compared the ability of some plant growth-promoting actinobacterial strains to form biofilms on a carrier to improve microbial survival and colonize the rhizosphere and roots of Triticum aestivum, resulting in positive interactions and benefits to the plant. Forty-one actinobacterial isolates from Persea americana organic rhizosphere farms were tested on plant growth and biofilm-forming capacities, showing their potential use as bio-fertilizers in agriculture. Three Streptomyces strains were selected and tested for biofilm formation and plant growth-promoting (PGP) features. Biofilms were induced on the perlite carrier and used to inoculate seven treatments with T. aestivum in pot essays, resulting in a >200% increase in root weight and a >400% increase in total biomass. Endophytic colonization was achieved in all the treatments. Microbial survival ranged between 108 and 109 CFU/g after 12 weeks of treatment, indicating actinobacterial permanence on the carrier. Successful consortia formation was observed for mixed-strain treatments, suggesting long-term plant recolonization.