Biotechnological Applications of Two Novel Lytic Bacteriophages of Streptococcus mutans in Tooth Decay Bio-Controlling

Isolation of the Bacteriophages Inhibiting the Expression of the Genes Involved in Biofilm Formation by Streptococcus mutans

Background: The potential of Streptococcus mutans for biofilm formation makes it one of the main organisms causing dental caries. Various preventive strategies have been applied to reduce tooth decay. Objectives: In the current study, we aimed to isolate S. mutans bacteriophages from sewage and to investigate their effects on the expression of the genes involved in bacterial biofilm formation in dental caries. Methods: Eighty-one dental plaque samples were collected. Then to isolate and identify S. mutans, bacterial culture media and molecular tests were used. Moreover, the biofilm formation capability of the isolated S. mutans was determined. Also, lytic bacteriophages were isolated from raw urban sewage, and phage morphology was determined by transmission electron microscopy (TEM). Real-time PCR was used to assess the effects of the isolated bacteriophages on the expression of the genes involved in biofilm formation. Results: Overall, 32 (39.5%) samples were positive for the presence of S. mutans. All of the isolates contained the gtfD gene. The frequencies of other genes were as follows: gtfB (17, 53.12%), gtfC (19, 53.37%), SpaP (13, 40.62%), and luxS (23, 17.87%). The isolated S. mutans bacteria presented different ranges of biofilm formation ability. Based on TEM results, two sewage-isolated bacteriophages, belonging to Siphoviridae and Tectiviridae families, were able to prevent biofilm formation up to 97%. Conclusions: Our findings indicate that phage therapy can be an optional way for controlling biofilm development and reducing the colonization of teeth surface by S. mutans.

Novel lytic bacteriophages of Klebsiella oxytoca ABG-IAUF-1 as the potential agents for mastitis phage therapy

Mastitis is an inflammation of the mammary gland that occurs when pathogenic microorganisms enter the udder. Even though tremendous advancements in veterinary diagnosis and therapeutics, mastitis is still the most frequent and costly disease of dairy herds overall the world. The purpose of this research was to isolate and identify the lytic phages as a potential method for biological control of bovine mastitis. In this study Klebsiella oxytoca was isolated from contaminated milk samples of Isfahan dairy herds, Isfahan, Iran and characterized as K. oxytoca ABG-IAUF-1 and its 16s-rRNA sequence was deposited in GenBank under the accession numbers of MF175803.1. Then, the four novel specific lytic bacteriophages of K. oxytoca ABG-IAUF-1 from Isfahan public wastewater were isolated and identified. The results of transmission electron microscopy indicated that theses isolated phages were related to Myoviridae and Podoviridae families of bacteriophages. Also the analysis of the growth curve of K. oxytoca ABG-IAUF-1 before and after treatment with lytic phage showed the 97% success rate of the phages in preventing of bacterial growth. This is the first report indicating the use of bacteriophages as the potential agents for eliminating the pathogenic bacteria responsible for bovine mastitis in Iran. The applications of these lytic phages could be an asset for biocontrolling of pathogenic agents in medical and veterinary biotechnology.