ISSN 2348-313X (Print) International Journal of Life Sciences Research ISSN 2348-3148 (online) Vol. 8, Issue 3, pp: (20-26), Month: July - September 2020, Available at: www.researchpublish.com
NEWLY ISOLATED VIBRIO CHOLERAE BACTERIOPHAGES FROM ENVIRONMENTAL WATERS OF KENYA Alice Nyambura Maina1,2, Francis B. Mwaura1, Miriam Jumba1, Peter Muturi3, Kering Kimutai3, David Goulding4, Derek Pickard4, Ana L. Toribio4, Julius M. Mathara5 1
University of Nairobi, School of Biological Sciences, P.O Box 30297-00100 Nairobi, Kenya 2
The Technical University of Kenya, P.O Box 52428-00200 Nairobi, Kenya
3
Kenya Medical Research Institute, P.O Box 54840-00200, Nairobi, Kenya
4
Wellcome Sanger Institute, Genome Campus, Hinxton, Cambridgeshire CB10 ISA, UK
5
Jomo Kenyatta University of Agriculture and Technology, P.O Box 62000-00200 Nairobi Kenya
Abstract: Viruses that infect bacteria are known as bacteriophages and can be used as biocontrol agents to complement antibiotics. The aim of the study was to isolate Vibrio cholerae lytic bacteriophages from environmental waters of different regions in Kenya that included: Lake Victoria, Coast, Nairobi and Central. A total of 140 environmental water samples were collected from ponds, rivers, lake, beaches, springs, boreholes, wells and Indian Ocean. Pathogenic Vibrio cholerae strains isolated from some these sources were used as respective propagating strains for isolation of vibriophages. Identification of the Vibrio cholerae bacterial strains by Polymerase Chain reaction was through amplification and sequencing of partial 16S ribosomal RNA gene. In total, 15 Vibrio cholerae bacteriophages were isolated; nine from rivers, three from beaches and three from ponds using the double layer method of purification. Lytic spectrum confirmed that all the 15 bacteriophages were infective to both environmental and clinical Vibrio cholerae isolates. Further characterization by Transmission Electron Microscope assigned the vibriophages to order Caudovirales of Myoviridae family owing to their icosahedral capsid and contractile tails. The average tail length, head diameter were 90nm and 79nm respectively. The current study has proved that vibriophages have established a niche in Kenyan environmental waters. The bacteriophages may have the potential for biocontrol of Vibrio cholerae bacterium. Keywords: Vibrio cholerae, vibriophages, cholera, biocontrol, Myoviridae.
I. INTRODUCTION Kenyan republic has suffered from cholera outbreaks for more than a decade due to heavy rains, poor sanitation and lack of access to clean, potable drinking water especially the low-income poor communities. Since December 2014, a cumulative total of 10,568 cases were reported in 2015 and 6,448 in 2016 [1]. In 2017, Kenya experienced a surge in cholera cases across the country, including urban outbreaks in the capital city, Nairobi. A total of 3,967 cases including 76 deaths were reported across 20 of 47 counties (43%) in the country. By the end of the year, seven counties continued to have active cholera outbreaks. There have also been cholera outbreaks in refugee camps in Kenya like Dadaab, Kakuma and Kalobeyei camps. In 2018, March to May long rains in Kenya were the heaviest in the past 55 years. A total of 5,756 cholera cases and 78 deaths were reported in 2018 [1]. Out of 47 counties, 20 were affected including: Mombasa, Kirinyaga, Garissa, Siaya, Tharaka Nithi, Meru, Tana River, and Turkana. There has been occurrence and persistence of V. cholerae in various aquatic systems like lakes and rivers. V.cholerae is discharged directly into the environment during an outbreak through the human excretions and waste water effluent from municipal councils [2]. Considering that cholera
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