Evaluation of Antimicrobial Activity in Enterobacter, Paenibacillus and Brevibacillus Species Isolated in Soil Samples From Lakes Magadi, Bogoria and Elementaita
Abstract
Species of genera Enterobacter, Paenibacillus and Brevibacillus are widely distributed
throughout the globe and they have been isolated in different habitats i.e. soil, saline and
alkaline water bodies, decaying plant materials, clinical materials and from the gut of animals
and human microbiota. Most species of these genera are known to produce antimicrobial
secondary metabolites with wide application in pharmaceutical, agricultural and food
industries. The emergence of pathogenic microorganisms with multiple drugs resistance has
raised the need to find more alternatives of potential active biological compounds from
natural resources. In this study, various species of genera Enterobacter, Paenibacillus and
Brevibacillus were isolated in soil samples from Lakes Magadi, Bogoria and Elementaita,
characterized and tested for their antimicrobial activity against various pathogenic
microorganisms with the aim of finding new antimicrobial compounds. Twenty-four isolates
of these genera were isolated and fermented in CY broth with amberlite XAD 16 (adsorbent
resin) for 7 days at 30o C. The antimicrobial compounds were extracted using methanol and
concentrated in rotary evaporator. Nine isolates presented antimicrobial activity against test
pathogenic bacteria (Salmonella spp., E. coli, Pseudomonas spp., K. pneumonia, S. aureus
and L. monocytogenes). Isolates Enterobacter sp. strain MC dung, Enterobacter sp. strain BC
dung, Brevibacillus sp. Strain BC/5BC, FU78CB, Enterobacter sp. strain FU 103BA and
Brevibacillus sp. strain ELHPS3H13 expressed broad spectrum against the test pathogenic
bacteria while Paenibacillus sp. Strain FU 75 BC, Enterobacter sp. FU 104C and BC5AC
showed narrow spectrum against Gram-negative bacteria (Salmonella spp., K. pneumonia,
Pseudomonas spp., and E. coli). Among the isolates, Enterobacter sp. strain BC dung had
significantly (P< 0.05) higher antibacterial activity against Pseudomonas spp. (Md=16mm),
S. aureus (Md= 35mm), Listeria monocytogenes (Md= 34mm) and K. pneumoniae (Md
=30mm). The morphological, biochemical and molecular characterization revealed that
isolates BC dung, MC dung, FU 104 C and FU 103 BA belong to genus Enterobacter,
BC/5BC and ELHPS3H13 belong to genus Brevibacillus, while isolates FU 75 BC, FU 78CB
and BC5AC belong to genera Paenibacillus, Providencia and Lysinibacillus respectively.
The isolated species of genera Enterobacter, Paenibacillus and Brevibacillus possessed
antimicrobial compounds which were active against the selected pathogenic bacteria.
Publisher
University of Nairobi
Rights
Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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