Genetic diversity of Bacillus sp producers of amylase isolated from the soil.

The microorganisms are the best source of extracellular enzymes since they allow an economical technology with low-resource consumption compared to animals and plants. The amylases are among the most important enzymes being the genus Bacillus one of the most investigated due to its ability to produce this enzyme. The objective of this study was to isolate and analyze the genetic diversity among bacteria of the genus Bacillus sp producer of amylase originated from the soil. To this end, soil samples were collected and submitted to the condition of extreme temperature. The serial dilution procedure followed by seeding on solid medium containing starch was used for isolation of strains that produce amylase. The microorganisms isolated were subjected to standard morphological methods for presumptive identification of the genus Bacillus. The PCR assay with the universal genetic marker 16S rDNA was used for confirmation of bacterial strain. All the 10 isolates presumptively identified as bacteria amplified a fragment of 370 bp corresponding to the 16S rDNA gene. The enzymatic activity was expressed as an enzymatic index (EI), after 24 h of incubation. All isolate producers of amylase exhibited EI ≥ 2.0. The determination of the genetic profile and the clonal relationship among the isolates were performed by the method of ERIC-PCR polymorphism. The isolates of Bacillus spp were divided into 2 groups (I and II). Through this method, the discriminatory capacity of this analysis of polymorphisms was verified in differing producer strains from those not producing amylase.

Phenotypic and genotypic characterization of Staphylococcus aureus isolates in milk from flocks diagnosed with subclinical mastitis.

The Staphylococcus aureus is the most common isolated microorganism in ruminant animal species diagnostic with clinical or subclinical mastitis. Dairy herds with these diseases can transfer S. aureus into the milk supply, which can lead to food poisoning in humans. The objective of this study was to evaluate the profile of antimicrobial susceptibility, the presence of femA gene, the genetic relationships among isolates of S. aureus obtained from milk originating from flocks diagnosed with subclinical mastitis in nine rural properties in the northern of Minas Gerais State. To this end, 498 samples of bovine milk tested positive for the California mastitis test (CMT) were subjected to morphological methods and biochemical patterns for microbiological presumptive identification of S. aureus. The PCR test with the genetic marker femA was used to confirm the species S. aureus. All the 26 isolates presumptively identified as S. aureus amplified a fragment of 132 bp corresponding to the femA gene. The profile of antimicrobial susceptibility was performed according to the disk-diffusion methodology and two isolates were susceptible to all the antibiotics tested. The drug multiresistence was found in 80.76% of the isolates. The determination of the genetic profile and the clonal relationship among the isolates was performed by the method of DNA RAPD-PCR polymorphism. The S. aureus isolates were divided into two groups with 26 distinct subgroups. The analysis of RAPD-PCR showed no genetic diversity among them, heterogeneous profile and absence of clonality.