Thirty-one Acetobacter strains obtained from culture collections and 45 Acetobacter strains isolated from Indonesian sources were investigated for their phenotypic characteristics, ubiquinone systems, DNA base compositions, and levels of DNA-DNA relatedness. Of 31 reference strains, six showed the presence of ubiquinone 10 (Q-10). These strains were eliminated from the genus Acetobacter. The other 25 reference strains and 45 Indonesian isolates were subjected to a systematic study and separated into 8 distinct groups on the basis of DNA-DNA relatedness. The known species, Acetobacter aceti, A. pasteurianus, and A. peroxydans are retained for three of these groups. New combinations, A. orleanensis (Henneberg 1906) comb. nov., A. lovaniensis (Frateur 1950) comb. nov., and A. estunensis (Carr 1958) comb. nov. are proposed for three other groups. Two new species, A. indonesiensis sp. nov. and A. tropicalis sp. nov. are proposed for the remaining two. No Indonesian isolates were identified as A. aceti, A. estunensis, and A. peroxydans. Phylogenetic analysis on the basis of 16S rDNA sequences was carried out for representative strains from each of the groups. This supported that the eight species belonged to the genus Acetobacter. Several strains previously assigned to the species of A. aceti and A. pasteurianus were scattered over the different species. It is evident that the value of DNA-DNA relatedness between strains comprising a new species should be determined for the establishment of the species. Thus current bacterial species without data of DNA-DNA relatedness should be reexamined for the stability of bacterial nomenclature.

Forty-six strains of acetic acid bacteria newly isolated from flowers, fruits, and fermented foods collected in Indonesia were taxonomically studied. They were Gram-negative rods, produced acetic acid from ethanol, oxidized acetate and lactate to CO2 and H2O, and had Q-9 as the major ubiquinone system. On the basis of DNA-DNA similarity, all strains studied, including type strains and reference strains of the genus Acetobacter, were separated into eleven groups (Groups I to XI). Of the 46 isolates, two isolates were included in Group II and identified as Acetobacter pasteurianus, five in Group IV as A. orleanensis, 16 in Group V as A. lovaniensis, five in Group VII as A. indonesiensis, and three in Group VIII as A. tropicalis. The remaining 15 isolates constituted three new groups based on DNA-DNA similarity; four isolates were included in Group IX, two in Group X, and nine in Group XI. No isolates were identified as A. aceti (Group I), A. peroxydans (Group III), and A. estunensis (Group VI). Phylogenetic analysis based on 16S rDNA sequences of representative strains of the Groups indicated belonging to the strains of the genus Acetobacter. On the basis of DNA base composition, DNA-DNA similarity, and 16S rDNA sequences, three new species of the genus Acetobacter are proposed: Acetobacter syzygii sp. nov. for Group IX, Acetobacter cibinongensis sp. nov. for Group X, and Acetobacter orientalis sp. nov. for Group XI. The distribution of Acetobacter strains in Indonesia is discussed in light of isolation sources.

Ten strains previously assigned toAcetobacter hansenii(=Gluconacetobacter hansenii),Acetobacter pasteurianusLMG 1584 and eight reference strains of the genusGluconacetobacterwere reclassified by 16S rRNA gene sequencing, DNA–DNA similarity, DNA base composition and phenotypic characteristics. TheA. hanseniistrains andA. pasteurianusLMG 1584 were included in the cluster of acetic acid bacteria (familyAcetobacteraceae) by 16S rRNA gene sequences. Further, they were separated into seven distinct groups by DNA–DNA similarity. DNA–DNA similarity group I was identified asG. hansenii. DNA–DNA similarity group II was retained asGluconacetobactersp., because DNA–DNA similarity between the strain andGluconacetobacter entaniiLTH 4560^Tcould not be determined. This was due to a lack of availability of the type strain from any source. DNA–DNA similarity group III was regarded as a novel species, for which the nameGluconacetobacter saccharivoranssp. nov. (type strain, LMG 1582^T=NRIC 0614^T) is proposed. DNA–DNA similarity group IV included the type strains ofGluconacetobacter oboediensandGluconacetobacter intermedius, and threeA. hanseniistrains. This group was identified asG. oboediensbecause high values of DNA–DNA similarity were obtained between the type strains andG. oboedienshas priority overG. intermedius. DNA–DNA similarity group V was identified asGluconacetobacter europaeus. DNA–DNA similarity group VI was regarded as a novel species, for which the nameGluconacetobacter nataicolasp. nov. (type strain, LMG 1536^T=NRIC 0616^T) is proposed. DNA–DNA similarity group VII was reclassified asGluconacetobacter xylinus. The description ofG. hanseniiis emended.

A novel, regular to irregular, coccoid-shaped, anaerobic, Fe(III)-reducing microorganism was isolated from the Guaymas Basin hydrothermal system at a depth of 2000 m. Isolation was carried out with a new technique using Fe(III) oxide as the electron acceptor for the recovery of colonies on solid medium. The isolate, designated strain 234T, was strictly anaerobic and exhibited a tumbling motility. The cells had a single flagellum. Strain 234T grew at temperatures between 65 and 90 degrees C, with an optimum at about 88 degrees C. The optimal salt concentration for growth was around 19 g l(-1). The isolate was capable of growth with H2 as the sole electron donor coupled to the reduction of Fe(III) without the need for an organic carbon source. This is the first example of a dissimilatory Fe(III)-reducing micro-organism capable of growing autotrophically on hydrogen. In addition to molecular hydrogen, strain 234T oxidizes pyruvate, acetate, malate, succinate, peptone, formate, fumarate, yeast extract, glycerol, isoleucine, arginine, serine, glutamine, asparagine, stearate, palmitate, valerate, butyrate and propionate with the reduction of Fe(III). This isolate is the first example of a hyperthermophile capable of oxidizing long-chain fatty acids anaerobically. Isolate 234T grew exclusively with Fe(III) as the sole electron acceptor. The G+C content was 58.7 mol%. Based on detailed analysis of its 16S rDNA sequence, G+C content, distinguishing physiological features and metabolism, strain 234T is proposed to represent a novel genus within the Archaeoglobales. The name proposed for strain 234T is Geoglobus ahangari gen. nov., sp. nov..

Six actinomycete strains isolated from soil and plant-litter samples in Indonesia were studied for their taxonomic position by using a polyphasic approach. Phylogenetically, all the strains were located in the broad cluster of the genus Actinokineospora. Chemotaxonomic data [cell-wall diamino acid, meso-diaminopimelic acid; cell-wall peptidoglycan, type III (A1γ); major sugars, galactose and arabinose; major menaquinone, MK-9(H₄); major fatty acid, iso-C_16 : 0; major phospholipid, phosphatidylethanolamine] supported the affiliation of all six strains to the genus Actinokineospora. The results of DNA–DNA hybridization with DNA from type strains of Actinokineospora species with validly published names revealed three DNA–DNA relatedness groups. Group I (ID03-0561^T) showed low relatedness to the other strains studied. The three strains in group II (ID03-0784^T, ID03-0808 and ID03-0809) formed a group with high relatedness (98–100 %) and showed low relatedness to the other strains studied. The two strains in group III (ID03-0810^T and ID03-0813) showed 58–68 % relatedness to Actinokineospora terrae NBRC 15668^T and showed low relatedness (2–24 %) to the other strains studied. The description of three novel species is proposed: Actinokineospora baliensis sp. nov., for the single strain in group I (type strain ID03-0561^T =BTCC B-554^T =NBRC 104211^T), Actinokineospora cibodasensis sp. nov., for the strains in group II (type strain ID03-0784^T =BTCC B-555^T =NBRC 104212^T), and Actinokineospora cianjurensis sp. nov., for the strains in group III (type strain ID03-0810^T =BTCC B-558^T =NBRC 105526^T).

Mannan endo-1,4-β-mannosidase (commonly known as β-mannanase) catalyzes a random cleavage of the β-d-1,4-mannopyranosyl linkage in mannan polymers. The enzyme has been utilized in biofuel production from lignocellulose biomass, as well as in production of mannooligosaccharides (MOS) for applications in feed and food industries. We aimed to obtain a β-mannanase, for such mannan polymer utilization, from actinomycetes strains isolated in Indonesia. Strains exhibiting high mannanase activity were screened, and one strain belonging to the genus Kitasatospora was selected. We obtained a β-mannanase from this strain, and an amino acid sequence of this Kitasatospora β-mannanase showed a 58–71% similarity with the amino acid sequences of Streptomyces β-mannanases. The Kitasatospora β-mannanase showed a significant level of activity (944 U/mg) against locust bean gum (0.5% w/v) and a potential for oligosaccharide production from various mannan polymers. The β-mannanase might be beneficial particularly in the enzymatic production of MOS for applications of mannan utilization.