Utilization of n-alkanes by a newly isolated strain of Acinetobacter venetianus: the role of two AlkB-type alkane hydroxylases

Abstract

A bacterial strain capable of utilizing n-alkanes with chain lengths ranging from decane (C10H22) to tetracontane (C40H82) as a sole carbon source was isolated using a system for screening microorganisms able to grow on paraffin (mixed long-chain n-alkanes). The isolate, identified according to its 16S rRNA sequence as Acinetobacter venetianus, was designated A. venetianus 6A2. Two DNA fragments encoding parts of AlkB-type alkane hydroxylase homologues, designated alkMa and alkMb, were polymerase chain reaction-amplified from the genome of A. venetianus 6A2. To study the roles of these two alkM paralogues in n-alkane utilization in A. venetianus 6A2, we constructed alkMa, alkMb, and alkMa/alkMb disruption mutants. Studies on the growth patterns of the disruption mutants using n-alkanes with different chain lengths as sole carbon source demonstrated central roles for the alkMa and alkMb genes in utilization of C10 to C18 n-alkanes. Comparative analysis of these patterns also suggested different substrate preferences for AlkMa and AlkMb in n-alkane utilization. Because both single and double mutants were able to grow on n-alkanes with chain lengths of C20 and longer, we concluded that yet another enzyme(s) for the utilization of these n-alkanes must exist in A. venetianus 6A2.

Involvement of an Alkane Hydroxylase System of Gordonia sp. Strain SoCg in Degradation of Solid n -Alkanes

“…Consumption of n-triacontane is more rapid than that of n-hexadecane, in contrast with lower biomass accumulation on the longest alkane. It appears that the efficiency of the AH system is reduced with increasing chain length, as previously reported for other strains (5,20,21,24,28).…”

“…Growth of SoCg on triacontane would be poorer that that on hexadecane for this reason and also because a second, unknown system, that is functional on C 16 but not on C 30 , would contribute to overcome the limiting step of n-alkane degradation on C 16 . The alkane hydroxylase, in fact, catalyzes the initial attack and determines the size range of n-alkanes to be degraded; its specific activity is generally reduced with increasing chain length (5,20,21,24,28).…”

“…Many bacterial strains contain multiple, and quite divergent, integral membrane AlkBs (31) that have different substrate ranges (23,24) or are activated during different growth phases (13). The strategy of Gordonia SoCg seems to be based on a single alkB gene, which is induced by a wide range of long and solid n-alkanes throughout the time course of growth (L. Lo Piccolo, unpublished results), encoding an enzyme with highest activity on hexadecane and reduced activity on triacontane.…”

EliA is required for inducing the stearyl alcohol-mediated expression of secretory proteins and production of polyester in Ralstonia sp. NT80

“…This observation suggested that stearyl alcohol induces expression of many extracellular proteins and prompted us to investigate the multiple aspects of NT80 cells' response to stearyl alcohol. Several previous studies reported the effects of methanol and ethanol on bacterial cells (Hendrickson et al, 2010;Lu et al, 2012) and several other studies examined the mechanism of assimilation of n-alkanes by bacteria (Bouchez Naïtali et al, 1999;Tani et al, 2001;Throne-Holst et al, 2006). The effects of fatty alcohols on bacterial cells, however, have hardly been explored.…”

Isolation and Characterization of a Novel Medium-Long Alkane-Degrading Strain

“…S14-10 [19] 、Geobacillus thermodenitrificans NG80 [20] 等菌株的烷烃降解酶系和相关基因。已 报道的 AlkBs 和 CYP153s 都是负责中等链长烷烃 (C 5~C12 )的降解，对于长链烷烃羟化酶 AlmA 和 LadA 的报道却不多见。Maier T 等人 [21] 从 Acinetobacter calcoaceticus EB104 克隆到了参与烷烃羟化的 P450 基 因。Mimmi Throne-Holst 等人 [22,23] …”