Petroleum-hydrocarbon-degrading bacteria were obtained after enrichment on crude oil (as a 'chocolate mousse') in a continuous supply of Indonesian seawater amended with nitrogen, phosphorus and iron nutrients. They were related to Alcanivorax and Marinobacter strains, which are ubiquitous petroleum-hydrocarbon-degrading bacteria in marine environments, and to Oceanobacter kriegii (96.4-96.5 % similarities in almost full-length 16S rRNA gene sequences). The Oceanobacter-related bacteria showed high n-alkane-degrading activity, comparable to that of Alcanivorax borkumensis strain SK2. On the other hand, Alcanivorax strains exhibited high activity for branched-alkane degradation and thus could be key bacteria for branched-alkane biodegradation in tropical seas. Oceanobacter-related bacteria became most dominant in microcosms that simulated a crude oil spill event with Indonesian seawater. The dominance was observed in microcosms that were unamended or amended with fertilizer, suggesting that the Oceanobacter-related strains could become dominant in the natural tropical marine environment after an accidental oil spill, and would continue to dominate in the environment after biostimulation. These results suggest that Oceanobacter-related bacteria could be major degraders of petroleum n-alkanes spilt in the tropical sea. INTRODUCTIONA wide variety of micro-organisms are known to degrade petroleum hydrocarbons (Head et al., 2006;Prince, 2005). Most hydrocarbonoclastic bacteria metabolize either aliphatic or aromatic hydrocarbons, although some bacteria such as strains of Pseudomonas (Whyte et al., 1997) and Rhodococcus (Andreoni et al., 2000) have been shown to degrade both types of hydrocarbons. Among hydrocarbonoclastic bacteria, Alcanivorax (Hara et al., 2003;Kasai et al., 2001;Roling et al., 2004;Yakimov et al., 1998Yakimov et al., , 2005 and Cycloclasticus (Dyksterhouse et al., 1995;Kasai et al., 2002a;Maruyama et al., 2003) strains have been identified as key micro-organisms in the degradation of aliphatic and aromatic hydrocarbons, respectively, in marine environments (Harayama et al., 2004). Alcanivorax strains are distributed in natural marine environments around the world . The ability of Alcanivorax strains to use branched alkanes is high (Hara et al., 2003;McKew et al., 2007), and this could be one of the reasons why these strains predominate in crude-oil-impacted temperate marine environments (Cappello et al., 2007;Hara et al., 2003;Kasai et al., 2001;Roling et al., 2002Roling et al., , 2004Yakimov et al., 2005). Thalassolituus oleivorans has been reported to degrade aliphatic hydrocarbons (Yakimov et al., 2004), and Thalassolituus strains have recently been shown to dominate in n-alkane-containing temperate seawater microcosms (McKew et al., 2007;Yakimov et al., 2005) and in crude-oil-containing temperate estuarine seawater microcosms (Coulon et al., 2007;McKew et al., 2007).In addition to these 'professional' hydrocarbonoclastic bacteria, many 'non-professional' hydrocarbonoclastic bacteria such as Mar...

Three Gram-negative, motile, mesophilic, aerobic, rod-shaped bacterial strains, designated 2O1T, 1O14 and 1O18, were isolated from Indonesian seawater after enrichment with crude oil and a continuous supply of supplemented seawater. The strains exhibited high n-alkane-degrading activity, which indicated that the strains were important degraders of petroleum aliphatic hydrocarbons in tropical marine environments. Phylogenetic analyses based on 16S rRNA gene sequences of members of the Gammaproteobacteria showed that the isolates formed a coherent and distinct cluster in a stable lineage containing Oceanobacter kriegii IFO 15467T (96.4–96.5 % 16S rRNA gene sequence similarity) and Thalassolituus oleivorans MIL-1T. DNA G +C content was 53.0–53.1 mol%. The major fatty acids were C16 : 0, C16 : 1 ω7 and C18 : 1 ω9 and the hydroxy fatty acids were C12 : 0 3-OH and C10 : 0 3-OH. The polar lipids were phosphatidylglycerol, a ninhydrin-positive phospholipid(s) and glycolipids. The major quinone was Q-9 (97–99 %), which distinguished the isolates from Oceanobacter kriegii NBRC 15467T (Q-8; 91 %). On the basis of phenotypic, genotypic and chemotaxonomic data, including DNA–DNA hybridization, the isolates represent a novel genus and species, for which the name Oleibacter marinus gen. nov., sp. nov. is proposed. The type strain of Oleibacter marinus is 2O1T (=NBRC 105760T =BTCC B-675T).

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Jakarta Bay has been known as one of the most polluted marine environment in Indonesia, with no exception by oil. Seribu Islands waters, located in the north of Jakarta Bay may have been impacted by this polluted condition.It’s sometimes also hit by oil spillage from pipe leakage. The purpose of this study is to isolate and identify hydrocarbonoclastic bacteria (oil and Polyaromatic Hydrocarbon degrading bacteria) from Jakarta Bay and Seribu Island waters. The bacteria were isolated from water and sediment/sand. Isolation was prepared by enriched samples in SWP medium with Arabian Light Crude Oil (ALCO). Screening for PAH degrading bacteria has been completed by using sublimation plate method in ONR7a medium and screening for oil degrading bacteria were conducted by using oil plated method with the same medium. Bacteria identifications were done based on l6sRNA gene. The results were analyzed using BLAST and showed that 131 potential hydrocarbonoclastic bacteria have been isolated from Jakarta Bay and Seribu Island waters. Most of them were oil degrading bacteria (41.98%) and the rest were PAH degrading bacteria. Oil pollution level may impact the number of strain of hydrocarbonoclastic bacteria isolated. Among the hydrocarbonoclastic bacteria isolated from Jakarta Bay and Seribu Islands, Alcanivorax, Marinobacter, Achromobacter and Bacillus were common hydrocarbonoclastic genera in Jakarta Bay and its surrounding waters. Alcanivorax spp. is important oil and PAH-degrader found not only in temperate waters, but in tropical waters as well.

<p>An investigation of bacteria as holothurians’s feed carried out from May until June 2006 in Medane Bay and Kombal Bay, Lombok, Indonesia. The aims of this study are to know whether holothurians eat bacteria, to observe that bacteria are the key for holothurians’ habitat preference, and to understand the functions of bacteria in holothurians intestine. The results showed there are many kind of bacteria in the substrates and inside intestine of sea cucumber. There are no specificity in performance, species and number of bacteria which found in anterior or posterior of intestine, as well in their substrates. Therefore, the holothurians do not choose specific bacteria for their feed. Bacteria are the consequence of substrates ingested. Some of them can be microflora in holothurians intestine. Bacteria inside holothurians produce some enzymes such as protease, amylase and agarase. This function was proven by the increasing of Total Organic Matters (TOM) in their feces. This evidence supporting Wiedmeyer (1992) statement that sea cucumber adds organic matters in the sediment. So this also firm holothurians’ function in their habitat, as supplier for organic matters. The conclusion is that bacteria are eaten by holothurians by absorption, bacteria is not the key for microhabitat preference for holothurians, and inside the intestine of holothurians, digestion and degradation are the function of bacteria by producing their enzymes.</p><p>Keywords: bacteria, holothurians, microhabitat preference, function</p>