IMR Press / FBE / Volume 14 / Issue 2 / DOI: 10.31083/j.fbe1402015
Open Access Original Research
Specificity of Rhodococcus opacus 1CP cells’ responses to benzoate and 3-chlorobenzoate
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1 G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Pushchino, 142290 Moscow Region, Russian Federation
*Correspondence: (Inna P. Solyanikova)
These authors contributed equally.
Academic Editor: Yasuhito Shimada
Front. Biosci. (Elite Ed) 2022, 14(2), 15;
Submitted: 11 November 2021 | Revised: 21 January 2022 | Accepted: 24 January 2022 | Published: 2 June 2022
Copyright: © 2022 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license.

Background: Halogenated aromatic compounds are more resistant to microbial degradation than non-halogenated aromatic compounds. Microbial degradation of sodium benzoate in the presence of sodium 3-chlorobenzoate is of interest. The ability to degrade aromatic compounds is largely determined by the substrate specificity of the first enzyme that initiates degradation, namely, benzoate 1,2-dioxygenase for benzoate degradation, and 3-chlorobenzoate 1,2-dioxygenase for 3-chlorobenzoate degradation. In this study, the perspective of immobilized cells of Rhodococcus opacus 1CP actinobacterium for degradation of benzoate and 3-chlorobenzoate was explored. Methods: The biosensor approach (a membrane microbial sensor based on immobilized cells of Rhodococcus opacus 1CP and the Clark-type oxygen electrode as a transducer) was applied to evaluate the actinobacterial cells’ responses to benzoate and 3-chlorobenzoate in the absence of both enzymes, benzoate 1,2-dioxygenase and 3-chlorobenzoate 1,2-dioxygenase, or in the presence of one of the said enzymes. Results: Data obtained show that 1CP actinobacterium possessed a constitutive system for the transport of benzoate and 3-chlorobenzoate into culture cells. The affinity of the transport system for benzoate was higher than that for 3-chlorobenzoate. Moreover, adaptation to one substrate did not preclude the use of the second substrate. Probably, porins facilitated the penetration of benzoate and 3-chlorobenzoate into 1CP cells. Analyzing V vs. S dependencies, negative cooperativity was found, when benzoate 1,2-dioxygenase bound substrate (3-chlorobenzoate), while positive cooperativity was determined at benzoate binding. The observed difference could be associated with the presence of at least two systems of 3-chlorobenzoate transport into actinobacterial cells and allosteric interaction of active sites of benzoate 1,2-dioxygenase in the presence of 3-chlorobenzoate. Conclusions: The membrane microbial sensor based on immobilized Rhodococcus opacus 1CP cells could be useful as a perspective tool for comparative evaluation of enzymes of complex structure such as benzoate- and 3-chlorobenzoate 1,2-dioxygenase.

Rhodococcus opacus 1CP actinobacterium
benzoate 1
3-chlorobenzoate 1
immobilized cells
membrane microbial sensor
Fig. 1.
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