Screening, isolation and characterization of large bacteriophages for use in biocontrol of a wide-range of pathogenic bacteria

概要

The continuous decline in the effectiveness of antibiotics and increased rates of bacterial
resistance represents a public health challenge universally (Lin et al., 2017). It has been suggested
that by 2050, around 10 million people could die per year due to antimicrobial resistance (O'neill,
2014). Focus must be turned towards alternative approaches for treating infections. One of the
most promising strategy is the use of bacterial viruses, the natural predators of bacteria known as
bacteriophages or phages (Ghosn et al., 2019). Bacteriophages represent the major biological
organisms on the earth with an estimated 1031 bacteriophages (Hendrix et al., 1999; Keen, 2015).
They are capable of killing bacteria as effectively as antibiotics and are far more flexible in their
capabilities (Drulis-Kawa et al., 2012), as they can overcome almost all disadvantages of
antibiotics.
Bacteriophages can be classified according to their genome sizes into small and large phages.
To date reported sizes of all isolated and characterized phages were varied between 3,300 base of
ssRNA viruses of Escherichia coli (small phages) to almost 500 kbp of dsDNA genome phage G
of Bacillus megaterium (jumbo phages) (Hatfull and Hendrix, 2011; Yuan and Gao, 2017).
Interestingly, jumbo phages with genome sizes more than 200 kbp are characterized by their wider
host range (Bhunchoth et al., 2015), sustainability and long-lasting lytic infection (Yamada et al.,
2010).
Unfortunately, there was no specific method to isolate large phages. As almost all of large
phages have been isolated by chance (Yuan and Gao, 2017) by using classical methods for
screening of bacteriophages. My first goal in this study is to develop a specific method for selective
screening of large phages. To investigate the host range of isolated large phages, we prepared
several hosts including Gram positive and Gram negative bacteria with focus on members of
the Enterobacteriaceae. As gastrointestinal infections caused by pathogenic strains of
Enterobacteriaceae are considered as serious economic and public health problem worldwide
(Logan and Weinstein, 2017). They are leading causes of death among human beings especially
young children because of severe diarrhea (Humphrey et al., 2015). Moreover, they were reported
in the list of global priority pathogens (Tacconelli et al., 2018). ...

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