Akademik Veri Yönetim Sistemi
Turk Hijyen ve Deneysel Biyoloji Dergisi, cilt.81, sa.2, ss.121-134, 2024 (Scopus)
Objective: Methicillin-resistant Staphylococcus aureus (MRSA) is a clinically common and has a high mortality rate pathogen, as well as a bacterium that causes infection through food. To combat with pathogens, it is commonly preferred to create osmotic stress in their environment but S. aureus is able to synthesize some osmoprotectant substances such as betaine. There is limited literature about the synthesis pathways and gene expressions of these substances. This study aims to search the metabolic pathways of osmoprotectan production of S. aureus by comparing the bacterial behaviour with the expression of genes responsible for betaine. Methods: In the current study, different concentrations of NaCl and KCl salts (0.5, 1.0, 1.5, 2.0 and 3.0 M) were applied to Staphylococcus aureus ATCC 43300, changes in the number of viable cells of the bacteria were monitored and associated with osmoprotectant production. Bacterial numbers treated with salt were counted by culturel and spectrophotometric methods and viability graphs were created. Simultaneously, metabolic pathways under stress conditions were determined by monitoring the expression of genes responsible for betaine in RT-PCR. Results: When the growth curve of the bacterium is examined in NaCl or KCl salt stress, it was observed that the bacteria exited the logarithmic phase and was more affected by the stress conditions, especially at 12–24 time interval which is critical in the development of bacteria. The most notable results in the RT-PCR trials of the study were obtained when 1.5 M NaCl was present in the growth media at 36th hour of incubation. Under these conditions, a significant decrease of (-2.37-fold) in the betA gene was observed. Contrary to this result, 2.57-fold increase in the betA gene and 3.25-fold increase in the betB-gbsA gene was observed when 2 M KCl was present in the medium at 48th hour of incubation. Conclusion: During the 48-hour incubation period in which the bacterial growth was followed, it was observed that the bacteria exhibited a fluctuating growth curve against the salt stress and exhibited a different behavior than expected in the growth kinetics.