Alkanindiges illinoisensis gen. nov., sp. nov., an obligately hydrocarbonoclastic, aerobic squalane-degrading bacterium isolated from oilfield soils

Abstract

Alkanindiges illinoisensis gen. nov., sp. nov., an obligately hydrocarbonoclastic, aerobic squalanedegrading bacterium isolated from oilfield soils An alkane-degrading bacterium, designated GTI MVAB Hex1 T , was isolated from chronically crude oil-contaminated soil from an oilfield in southern Illinois. The isolate grew very weakly or not at all in minimal or rich media without hydrocarbons. Straight-chain aliphatic hydrocarbons, such as hexadecane and heptadecane, greatly stimulated growth; shorter-chain (¡C 15 ) hydrocarbons did not (with decane as the sole exception). Growth was also greatly enhanced by the branched aliphatic hydrocarbons pristane and squalane. The latter of these was most intriguing, as catabolism of squalane has hitherto been reported only for Mycobacterium species. Although unable to utilize mono-or polycyclic aromatic hydrocarbons as sole carbon sources, the isolate did show slight fluorene-mineralizing capability in Luria-Bertani medium, which was partially repressed by hexadecane. In contrast, hexadecane supplementation greatly increased mineralization of 14 C-dodecane, which was not a growth substrate. Further testing emphasized the isolate's extremely narrow substrate range, as only Tween 40 and Tween 80 supported significant growth. Microscopic examination (by scanning and transmission electron microscopy) revealed a slightly polymorphic coccoidal to bacillar morphology, with hydrocarbon-grown cells tending to be more elongated. When grown with hexadecane, GTI MVAB Hex1 T accumulated a large number of electron-transparent intracytoplasmic inclusion bodies. These were also prevalent during growth in the presence of squalane. Smaller inclusion bodies were observed occasionally with pristane supplementation; they were, however, absent during growth on crude oil. On the basis of 16S rRNA gene sequence data and range of growth substrates, classification of this isolate as the type strain of Alkanindiges illinoisensis gen. nov., sp. nov. is proposed, which is most closely related (approx. 94 % sequence similarity) to Acinetobacter junii.Bacterial biodegradation of crude oil first gained widespread attention as a potential remediation approach in the 1970s (Atlas & Bartha, 1972;Soli & Bens, 1972). Many bacteria degrade aliphatic constituents of crude oils, including straight-chain aliphatic hydrocarbons up to C 44 (Sakai et al., 1994;Radwan et al., 1996). Branched-chain alkanes, particularly those with anteiso-terminal branching [substitution on carbon atoms that are immediately adjacent to the terminal carbon atom(s)], are much less susceptible to b-oxidation (Schaeffer et al., 1979), and thus more recalcitrant, than their unbranched counterparts. Thus, pristane (2,6,10,14-tetramethylpentadecane) was often used as an internal standard to determine biodegradation and weathering of other oil fractions (Alvarez et al., 2001). More recently, however, species of several genera have been shown to biodegrade pristane (McKenna & Kallio, 1971;Pirnik et al., 1974;Nakajima & Sato, 1983;Lal & Khanna, ...

Physiological and molecular characterization of a microbial community established in unsaturated, petroleum‐contaminated soil

“…It has been reported that this type of methanotrophic bacteria was strongly associated with the oxic–anoxic interface in water columns or sediments, implying that oxic and anoxic zones were present in the SC soil. Another group (phylotypes BSC40 and BSC46) was related to Alkanindiges illinoisensis (91.3%), an aerobic squalane‐degrading bacterium recently isolated from oilfield soil (Bogan et al ., 2003). This bacterium has been reported to grow on long aliphatic hydrocarbons, including straight and branched ones, implying that organisms related to Alkanindiges may play a role in the aerobic degradation of petroleum hydrocarbons.…”

Alkane-degrading bacteria at the soil-litter interface: comparing isolates with T-RFLP-based community profiles

“…For instance, some oligotrophic bacteria (i.e. Their life strategy might be similar to that of the hydrocarbonoclastic bacteria (Bogan et al, 2003;Rojo, 2009), which have high environmental relevance in case of contamination. In contrast, many copiotrophs (e.g.…”

A Novel Lineage of Proteobacteria Involved in Formation of Marine Fe-Oxidizing Microbial Mat Communities

“…Next the cells were washed with distilled water and stained with 1% aqueous uranyl acetate, then dehydrated in an ethanol series and embedded in Spurr resin. Thin sections were cut on an LKB Nova ultramicrotome, post-stained with uranyl acetate and lead citrate, and observed and photographed in a Zeiss EM-10CA TEM [43].…”