Identification and Characterization of Staphylococcus aureus 16S rRNA gene isolated from different Food Specimens from South Indian Region

Abstract

Staphylococcus aureus (S. aureus) associated food-borne diseases have global impact on human health. Genome wide analyses have shown that S. aureus contains specific endotoxin expressing gene and produce toxic proteins which is responsible for food contamination. Appropriate detection of pathogens is one of the major tool to avoid infection rate and reduce the health and socio-economic burden to human being. In addition, inappropriate handing the specimens, misdiagnosis and limited standard medical support could directly influence the infection rate.
 The objective of this study was to identify S. aureus from different food specimens from Hyderabad, India. A total of 70 random bacterial nutrient agar medium pure plates were made based on different morphological appearance of bacterial colonies. Preliminary identification of S. aureus based on standardized morphological method showed specific golden yellow colonies. Biochemical assay also verified bacterial specimens. Furthermore, molecular characterization was performed on the basis of polymerase chain reaction (PCR) and sequencing of 16S rRNA gene of S. aureus. Newly sequenced 16S rRNA gene sequences showed 100% homology to S. aureus, analyzed using NCBI-BLAST tool.
 The phylogenetic analysis and nucleotide base composition studies performed using 39 sequences of 16S rRNA gene from different isolates of Staphylococcus, including Staphylococcus aureus. For the purpose, 16S rRNA gene sequences were retrieved from the NCBI in FASTA format. The phylogenetic analysis was performed using Maximum Likelihood method and revealed the relationships and percent similarity of Staphylococcus aureus 16S rRNA gene. 
 Keywords: Food-borne diseases; 16S rRNA gene; Maximum Likelihood; Phylogenetic analysis; Staphylococcus aureus.