Dwi Susilaningsih

Tropicibacter naphthalenivorans gen. nov., sp. nov., a polycyclic aromatic hydrocarbon-degrading bacterium isolated from Semarang Port in Indonesia

An aerobic, Gram-negative, motile bacterium, strain C02(T), was isolated from seawater obtained from Semarang Port in Indonesia. Cells of strain C02(T) were peritrichously flagellated and rod-shaped. Strain C02(T) was able to degrade naphthalene, alkylnaphthalenes and phenanthrene. 16S rRNA gene sequence analysis revealed that this strain was affiliated with the family Rhodobacteraceae in the class Alphaproteobacteria and was related most closely to Marinovum algicola FF3(T) (95.7 % similarity) and Thalassobius aestuarii JC2049(T) (95.2 %). The DNA G+C content of strain C02(T) was 64.6 mol%. The major cellular fatty acids were C(18 : 1)omega7c (50.9 % of the total), C(16 : 0) (17.9 %), 11 methyl C(18 : 1)omega7c (14.7 %), C(18 : 1)omega9c (2.9 %) and C(19 : 0) cyclo omega8c (2.4 %), and the predominant respiratory lipoquinone was ubiquinone-10. Based on physiological, chemotaxonomic and phylogenetic data, strain C02(T) is suggested to represent a novel species of a new genus, for which the name Tropicibacter naphthalenivorans gen. nov., sp. nov. is proposed. The type strain of Tropicibacter naphthalenivorans is C02(T) (=JCM 14838(T)=DSM 19561(T)).

Tropicimonas isoalkanivorans gen. nov., sp. nov., a branched-alkane-degrading bacterium isolated from Semarang Port in Indonesia

An aerobic, Gram-negative, motile bacterium, strain B51(T), was isolated from seawater obtained from Semarang Port in Indonesia. Cells of strain B51(T) were peritrichously flagellated and rod-shaped. Strain B51(T) was able to degrade alkanes, branched alkanes and alkylnaphthalenes. 16S rRNA gene sequence analysis revealed that strain B51(T) was affiliated with the family Rhodobacteraceae, and was related most closely to Thioclava pacifica TL 2(T) (94.6 % similarity). The DNA G+C content of strain B51(T) was 66.5 mol%. The major cellular fatty acids were C(18 : 1)omega7c (84.9 %), C(18 : 1)omega9c (13.8 %), C(16 : 0) (8.7 %), C(18 : 0) (6.4 %) and anteiso-C(15 : 0) (5.8 %) and the major quinone was ubiquinone-10. Based on its phenotypic and phylogenetic characteristics, strain B51(T) is considered to represent a novel species of a new genus, for which the name Tropicimonas isoalcanivorans gen. nov., sp. nov. is proposed. The type strain of the type species is B51(T) (=JCM 14837(T)=DSM 19548(T)).

Isolation and Screening of Surfactant-producing Bacteria from Indonesian Marine Environments and Its Application on Bioremediation

Isolation and screening have been undertaken on oil-degrading microbes from Indonesian marine environments. During screening process it has been found many bacterial isolates capable of degrading crude oil. Hence, study has been focused on the biodiversity of biosurfactant-producing bacterial species in Indonesian marine environment and its function for remedial the pollutant in marine and soil areas. A total of 103 out of 463 isolates showed positive surfactant-degrading properties. By means of partial 16S rRNA gene analyses, it has been found that the majority of taxa are related to Alcanivorax, Pseudomonas, Bacillus, Bortetela, Brucella, Acenitobacter, Staphia, Lysobacter, and Talasosophira . Biosurfactant properties assay showed that they were capable of lowering the surface- and interfacial water tension from 74 mN/m to 40-65 mN/m and from 24 mN/m to 6-10 mN/m, respectively. In addition, most of the surfactants were capable of emulsifying hydrocarbon (crude oil) of 0.01 to 0.15 units, comparable to 0.08 units of synthetic surfactant (20% Tween). Further observation showed that the majority of the surfactants were able to degrade a long chain of alkane, but not branched alkane, with a recovering rate of 20-80%. The application of the surfactant towards oil polluted model beach was done in laboratory scale and showing the surfactant obtained from microbial broth cultures capable for recovering the oil pollutant significantly, compared to the control (without addition microbial broth).