Protease-, Pectinase- and Amylase- Producing Bacteria from a Kenyan Soda Lake
Kevin Raymond Oluoch1, 2, *, Patrick Wafula Okanya2, Rajni Hatti-Kaul1, Bo Mattiasson1, Francis Jakim Mulaa2
Identifiers and Pagination:Year: 2018
First Page: 33
Last Page: 45
Publisher Id: TOBIOTJ-12-33
Article History:Received Date: 2/2/2018
Revision Received Date: 3/3/2018
Acceptance Date: 28/3/2018
Electronic publication date: 30/04/2018
Collection year: 2018
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Alkaline enzymes are stable biocatalysts with potential applications in industrial technologies that offer high quality products.
The growing demand for alkaline enzymes in industry has enhanced the search for microorganisms that produce these enzymes.
Eighteen bacterial isolates from Lake Bogoria, Kenya, were screened for alkaline proteases, pectinases and amylases; characterized and subjected to quantitative analysis of the enzymes they produced.
The screening analysis ranked 14, 16 and 18 of the bacterial isolates as potent producers of alkaline proteases, pectinases and amylases, respectively. The isolates were classified into two groups: Group 1 (16 isolates) were facultatively alkaliphilic B. halodurans while group 2 (2 isolates) were obligately alkaliphilic B. pseudofirmus. Further analysis revealed that group 1 isolates were divided into two sub-groups, with sub-group I (4 isolates) being a phenotypic variant sub-population of sub-group II (12 isolates). Variation between the two populations was also observed in their enzymatic production profiles e.g. sub-group I isolates did not produce alkaline proteolytic enzymes while those in sub-group II did so (0.01-0.36 U/ml). Furthermore, they produced higher levels of the alkaline pectinolytic enzyme polygalacturonase (0.12-0.46 U/ml) compared to sub-group II isolates (0.05-0.10 U/ml), which also produced another pectinolytic enzyme - pectate lyase (0.01 U/ml). No clear distinction was however, observed in the production profiles of alkaline amylolytic enzymes by the isolates in the two sub-populations [0.20-0.40 U/ml (amylases), 0.24-0.68 U/ml (pullulanases) and 0.01-0.03 U/ml (cyclodextrin glycosyl transferases)]. On the other hand, group 2 isolates were phenotypically identical to one another and also produced similar amounts of proteolytic (0.38, 0.40 U/ml) and amylolytic [amylases (0.06, 0.1 U/ml), pullulanases (0.06, 0.09 U/ml) and cyclodextrin glycosyl transferases (0.01, 0.02 U/ml)] enzymes.
The facultatively alkaliphilic B. halodurans and obligately alkaliphilic B. pseudofirmus isolates are attractive biotechnological sources of industrially important alkaline enzymes.