Characterization of 3-chlorobenzoate degrading aerobic bacteria isolated under various environmental conditions

Abstract

The rates of bacterial growth in nature are often restricted by low concentrations of oxygen or carbon substrates. In the present study the metabolic properties of 24 isolates that had been isolated using various concentrations of 3-chlorobenzoate, benzoate and oxygen as well as using continuous culture at high and low growth rates were determined to investigate the effects of these parameters on the metabolism of monoaromatic compounds. Bacteria were enriched from different sampling sites and subsequently isolated. In batch culture this was done both under low oxygen (2% O(2)) and air-saturated concentrations. Chemostat enrichments were performed under either oxygen or 3-chlorobenzoate limiting conditions. Bacteria metabolizing aromatics with gentisate or protocatechuate as intermediates (gp bacteria) as well as bacteria metabolizing aromatic compounds via catechols (cat bacteria) were isolated from batch cultures when either benzoate or 3CBA were used as C sources, regardless of the enrichment conditions applied. In contrast, enrichments performed in chemostats at low dilution rates resulted in gp-type organisms only, whereas at high dilution rates cat-type organisms were enriched, irrespective of the oxygen and 3-chlorobenzoate concentration used during enrichment. It is noteworthy that the gp-type of bacteria possessed relatively low µ(max) values on 3CBA and benzoate along with relatively high substrate and oxygen affinities for these compounds. This is in contrast with cat-type of bacteria, which seemed to be characterized by high maximum specific growth rates on the aromatic substrates and relatively high apparent half saturation constants. In contrast, bacteria degrading chlorobenzoate via gentisate or protocatechuate may possibly be better adapted to conditions leading to growth at reduced rates such as low oxygen and low substrate concentrations.

Naphthalene metabolism and growth inhibition by naphthalene in Polaromonas naphthalenivorans strain CJ2

“…Metabolism of aromatics via gentisate has been studied less extensively than metabolism via catechol, and it is not clear whether one pathway has an advantage over the other. A study investigating bacteria that metabolize 3-chlorobenzoate suggested that micro-organisms using the gentisate pathway have lower maximum specific growth rates and lower apparent half-saturation constants for oxygen and 3-chlorobenzoate; thus, they may be well adapted to substrate-and/or oxygen-limited conditions (Krooneman et al, 2000). If these same characteristics are applicable to strain CJ2, they could help explain why it is successful in naphthalene-contaminated sediments despite being sensitive to inhibitory effects of naphthalene.…”

Analysis of a Bacterial Community in 3-Chlorobenzoate-Contaminated Soil by PCR-DGGE Targeting the 16S rRNA Gene and Benzoate 1,2-Dioxygenase Gene (benA)

“…The benA PCR-DGGE was not designed for monitoring such a degrader (gp-type bacteria). Krooneman et al pointed out the possibility that gp-type bacteria play an important role in the degradation of 3CB, especially under conditions of low oxygen and low substrate concentrations 17) . So far as the present study is concerned, however, we thought that any contribution of gp-type bacteria to the degradation would be small, because the soil was aerobic and the concentration of 3CB was relatively high.…”

Optimizing the Biodegradation of 3,4-Dichlorobenzoic Acid by Corynebacterium jeikeium

“…6, No. 3;2014 Figure 5. The effect of adaptation on 3,4-DCBA biodegradation on the bacterial cells (C. jeikeium).…”

“…A huge number of bacterial and fungal genera possess the ability to degrade organic pollutants and these microorganisms are of particular relevance for the biodegradation of such compounds and are exemplarily described with reference to the degradation of aliphatic and aromatic hydrocarbons as well as their chlorinated derivatives. The most rapid and complete degradation of the majority of pollutants is brought about under aerobic conditions (Krooneman et al, 2000). The first dechlorination step of 3,4-DCB is catalyzed by the 4-CB dehalogenase, while a soluble dehalogenase was responsible for dechlorination of 3-C-4-OHB.…”