Genome sequencing reveals complex secondary metabolome in the marine actinomycete Salinispora tropica

Recent fermentation studies have identified actinomycetes of the marine-dwelling genus Salinispora as prolific natural product producers. To further evaluate their biosynthetic potential, we sequenced the 5,183,331-bp S. tropica CNB-440 circular genome and analyzed all identifiable secondary natural product gene clusters. Our analysis shows that S. tropica dedicates a large percentage of its genome ( approximately 9.9%) to natural product assembly, which is greater than previous Streptomyces genome sequences as well as other natural product-producing actinomycetes. The S. tropica genome features polyketide synthase systems of every known formally classified family, nonribosomal peptide synthetases, and several hybrid clusters. Although a few clusters appear to encode molecules previously identified in Streptomyces species, the majority of the 17 biosynthetic loci are novel. Specific chemical information about putative and observed natural product molecules is presented and discussed. In addition, our bioinformatic analysis not only was critical for the structure elucidation of the polyene macrolactam salinilactam A, but its structural analysis aided the genome assembly of the highly repetitive slm loci. This study firmly establishes the genus Salinispora as a rich source of drug-like molecules and importantly reveals the powerful interplay between genomic analysis and traditional natural product isolation studies.

Luedemannella gen. nov., a new member of the family Micromonosporaceae and description of Luedemannella helvata sp. nov. and Luedemannella flava sp. nov

Three actinomycete strains were isolated from soil samples collected in Bangladesh. The cultures formed spherical sporangia on short sporangiophores directly above the surface of the substrate mycelium. The sporangia developed singly or in clusters and each sporangium contained several nonmotile spherical to oval spores with a smooth surface. The strains 3-9(24)(T), 3-21(27) and 7-40(26)(T) contained meso-diaminopimelic acid in the cell walls, predominant menaquinone MK-9(H(6)) and MK-9(H(4)) and glucose, xylose, galactose, mannose, rhamnose, ribose and arabinose in the whole-cell hydrolysates. Diagnostic phospholipid is phosphatidylethanolamine and branched anteiso-C(17 : 0) (30.0-38.0%), anteiso-C(15 : 0) (12.5-14.0%), iso-C(16 : 0) (10.0-15.0%) and iso-C(15 : 0) (10.0-12.0%) were detected as the major cellular fatty acids. The acyl type of the peptidoglycan was glycolyl and mycolic acids were not detected. The G+C content of the DNA was 71 mol%. The chemotaxonomic data indicate that these strains belong to the family Micromonosporaceae. Phylogenetic analysis based on 16S rRNA gene sequence data suggested that the strains 3-9(24)(T), 3-21(27) and 7-40(26)(T) fall within the family Micromonosporaceae. On the basis of phylogenetic analysis and characteristic patterns of signature nucleotides as well as morphological and chemotaxonomic data, Luedemannella gen. nov. is proposed for our 3 isolates. DNA-DNA hybridization experiment and phenotypic characterization indicated that the new genus was constituted of 2 species, as Luedemannella helvata sp. nov. for the strain 3-9(24)(T) (=JCM 13249(T)=MTCC 8091(T)) and Luedemannella flava for the strain 7-40(26)(T) (=JCM 13250(T)=MTCC 8095(T)) in the family Micromonosporaceae.

Unique butyric acid incorporation patterns for salinosporamides A and B reveal distinct biosynthetic origins

Feeding sodium butyrate (0.25-1 mg/ml) to cultures of Salinispora tropica NPS21184 enhanced the production of salinosporamide B (NPI-0047) by 319% while inhibiting the production of salinosporamide A (NPI-0052) by 26%. Liquid chromatography mass spectrometry analysis of the crude extract from the strain NPS21184 fed with 0.5 mg/ml sodium [U-(13)C(4)]butyrate indicated that butyrate was incorporated as a contiguous four-carbon unit into NPI-0047 but not into NPI-0052. Nuclear magnetic resonance analysis of NPI-0047 and NPI-0052 purified from the sodium [U-(13)C(4)]butyrate-supplemented culture extract confirmed this incorporation pattern. The above finding is the first direct evidence to demonstrate that the biosynthesis of NPI-0047 is different from NPI-0052, and NPI-0047 is not a precursor of NPI-0052.

Biosynthetic convergence of salinosporamides A and B in the marine actinomycete Salinispora tropica

[structure: see text] Feeding experiments with stable isotopes established that the potent 20S-proteasome inhibitors salinosporamide A and B are biosynthesized in the marine bacterium Salinispora tropica from three biosynthetic building blocks, namely, acetate, beta-hydroxy-2'-cyclohexenylalanine, and either butyrate or a tetrose-derived chlorinated molecule. The unexpected observation that the chlorinated four-carbon residue in salinosporamide A is derived from a different metabolic origin than the non-chlorinated four-carbon unit in salinosporamide B is suggestive of a convergent biosynthesis to these two anticancer natural products.

Sequencing and analysis of the biosynthetic gene cluster of the lipopeptide antibiotic Friulimicin in Actinoplanes friuliensis

Actinoplanes friuliensis produces the lipopeptide antibiotic friulimicin, which is a cyclic peptide with one exocyclic amino acid linked to a branched-chain fatty acid acyl residue. The structural relationship to daptomycin and the excellent antibacterial performance of friulimicin make the antibiotic an attractive drug candidate. The complete friulimicin biosynthetic gene cluster of 24 open reading frames from A. friuliensis was sequenced and analyzed. In addition to genes for regulation, self-resistance, and transport, the cluster contains genes encoding peptide synthetases, proteins involved in the synthesis and linkage of the fatty acid component of the antibiotic, and proteins involved in the synthesis of the nonproteinogenic amino acids pipecolinic acid, methylaspartic acid, and 2,3-diaminobutyric acid. By using heterologous gene expression in Escherichia coli, we provide biochemical evidence for the stereoselective synthesis of L-pipecolinic acid by the deduced protein of the lysine cyclodeaminase gene pip. Furthermore, we show the involvement of the dabA and dabB genes in the biosynthesis of 2,3-diaminobutyric acid by gene inactivation and subsequent feeding experiments.

Species-specific secondary metabolite production in marine actinomycetes of the genus Salinispora

Here we report associations between secondary metabolite production and phylogenetically distinct but closely related marine actinomycete species belonging to the genus Salinispora. The pattern emerged in a study that included global collection sites, and it indicates that secondary metabolite production can be a species-specific, phenotypic trait associated with broadly distributed bacterial populations. Associations between actinomycete phylotype and chemotype revealed an effective, diversity-based approach to natural product discovery that contradicts the conventional wisdom that secondary metabolite production is strain specific. The structural diversity of the metabolites observed, coupled with gene probing and phylogenetic analyses, implicates lateral gene transfer as a source of the biosynthetic genes responsible for compound production. These results conform to a model of selection-driven pathway fixation occurring subsequent to gene acquisition and provide a rare example in which demonstrable physiological traits have been correlated to the fine-scale phylogenetic architecture of an environmental bacterial community.

Actinoplanes liguriensis sp. nov. and Actinoplanes teichomyceticus sp. nov

The taxonomic status of ‘Actinoplanes liguriae’ A/6353 and ‘Actinoplanes teichomyceticus’ AB8327 was established by using a polyphasic approach. Strains A/6353 and AB8327 form distinct phylogenetic lineages in the 16S rRNA gene tree of members of the genus Actinoplanes and are related moderately and closely to Actinoplanes rectilineatus and Actinoplanes cyaneus, respectively. Morphological, cultural and physiological properties indicated that strains A/6353 and AB8327 represent separate, novel species of the genus Actinoplanes, Actinoplanes liguriensis sp. nov. (type strain A/6353T=FH 2244T=DSM 43865T=ATCC 31048T=BCRC 12121T=CBS 355.75T=IMSNU 22127T=JCM 3250T=KCTC 9536T=KCC A-0250T=NBRC 13997T=NCIMB 12636T=NRRL B-16723T=SANK 62178T) and Actinoplanes teichomyceticus sp. nov. (type strain AB8327T=FH 2149T=DSM 43866T=ATCC 31121T=BCRC 12106T=FERM P-3462T=IMSNU 20043T=IMET 9254T=JCM 3252T=KCC A-0252T=KCTC 9543T=NBRC 13999T=NCIMB 12640T=NRRL B-16726T=SANK 60479T).

APPLICATION OF BIOCATALYSIS TO DRUG METABOLISM: PREPARATION OF MAMMALIAN METABOLITES OF A BIARYL-BIS-SULFONAMIDE AMPA (α-AMINO-3-HYDROXY-5-METHYLISOXAZOLE-4-PROPIONIC ACID) RECEPTOR POTENTIATOR USING Actinoplanes missouriensis

LY451395 (2-propanesulfonamide, N-[(2R)-2-[4'-[2-[methylsulfonyl)amino]ethyl][1,1'-biphenyl]-4-yl]propyl]-) is a potent and highly selective potentiator of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors. It is a biaryl-bis-sulfonamide and is known to be highly metabolized in preclinical species. In those metabolism studies, the metabolite structures were proposed exclusively by the analysis of mass spectrometric data. Although mass spectrometry is clearly a technique of choice for rapid identification of drug metabolites, occasionally, nuclear magnetic resonance spectroscopy is required to unambiguously assign and characterize, particularly, the regio- and stereochemistry of metabolic changes. Nuclear magnetic resonance spectroscopy, in general, is less sensitive than other detection methods and demands several micrograms of material for the analysis. To support full structure characterization of metabolites by NMR, in this study we demonstrated the application of a microbial-based surrogate biocatalytic system to produce sufficient amounts of the mammalian metabolites of LY451395. The results revealed that incubation of LY451395 with Actinoplanes missouriensis NRRL B3342 generated several metabolites that were previously detected in the in vivo metabolism studies of the preclinical species. Subsequent large-scale bioconversion resulted in the isolation of seven mammalian metabolites in milligram quantities for structural characterization by nuclear magnetic resonance spectroscopy. Furthermore, a selected group of metabolites generated from the microbial conversion served as analytical standards to monitor and quantify drug metabolites during clinical investigations.

Identification of linear plasmid pAM1 in the flavonoid degrading strain Actinoplanes missouriensis(T) (DSM 43046)

By pulsed-field gel electrophoresis, a linear DNA element of about 100 kb was identified in Actinoplanes missouriensis(T) DSM 43046, which grows on the flavonoids hesperidin, rutin and quercetin, and which contains a CO forming quercetinase. Among six Actinoplanes species and strains tested, including A. globisporus(T) DSM 43857, A. philippinensis(T) DSM 43019, A. brasiliensis(T) DSM 43805, A. auranticolor(T) DSM 43031, and A. utahensis(T) DSM 43147, only the A. missouriensis strain exhibited such a genetic element. The linear plasmid, named pAM1, has proteins covalently attached to its 5'-ends like other linear replicons of actinomycetes. Attempts to cure pAM1 failed, however a mutant with reduced plasmid content was obtained, which showed reduced ability to degrade the flavonoid rutinosides rutin and hesperidin. Plasmid pAM1 is the first extrachromosomal genetic element identified in an Actinoplanes species and may be useful to develop genetic tools for biotechnologically important Actinoplanes strains.

Characterization of maltose and maltotriose transport in the acarbose-producing bacterium Actinoplanes sp

Acarbose, a pseudomaltotetraose, is produced by strains of the genus Actinoplanes. The compound is an inhibitor of alpha-glucosidases and is used in the treatment of patients suffering from type II diabetes. The benefits of acarbose for the producer are not known; however, a role as carbophor has been proposed. Acarbose synthesis is induced in the presence of maltose and maltotriose. We have investigated the transport activities for these sugars in Actinoplanes sp. strain SN 223/29 grown on different carbon sources, including acarbose. Under the conditions used, Actinoplanes sp. utilized acarbose as sole source of carbon and energy, although growth ceased after 24 h, possibly due to the accumulation of a toxic degradation product in the cytosol. Maltose transport was observed in cells grown on each of the substrates tested except glucose. Maltose transport of acarbose-grown cells was inhibited by sucrose and trehalose and, to a lesser extent, by maltodextrins but not by acarbose. In contrast, in maltose/maltotriose-grown cells maltose uptake was inhibited by acarbose. Maltotriose uptake in these cells was less inhibited by maltose but was more sensitive to acarbose than in acarbose-grown cells. The Km and Vmax values of maltose uptake are in the range of those reported for binding protein-dependent sugar ATP-binding cassette (ABC) transport systems. A maltose-binding protein that does not bind acarbose was isolated from cells grown on either acarbose, glycerol or maltose. These results suggest that an acarbose-insensitive maltose/sucrose/trehalose transporter that also accepts maltodextrins operates in acarbose-grown cells while a maltodextrin transporter that accepts maltose/sucrose/trehalose and is moderately sensitive to acarbose is found in cells grown in maltose/maltotriose-containing media.

New Cytotoxic Salinosporamides from the Marine ActinomyceteSalinisporatropica

An extensive study of the secondary metabolites produced by the obligate marine actinomycete Salinispora tropica (strain CNB-392), the producing microbe of the potent proteasome inhibitor salinosporamide A (1), has led to the isolation of seven related gamma-lactams. The most important of these compounds were salinosporamide B (3), which is the deschloro-analogue of 1, and salinosporamide C (4), which is a decarboxylated pyrrole analogue. New SAR data for all eight compounds, derived from extensive testing against the human colon carcinoma HCT-116 and the 60-cell-line panel at the NCI, indicate that the chloroethyl moiety plays a major role in the enhanced activity of 1.

Influence of Leucine and Valine on Ramoplanin Production by Actinoplanes sp. ATCC 33076

Ramoplanin is a glycolipodepsipeptide antibiotic obtained by fermentation of the Actinoplanes sp. ATCC 33076, isolated as a complex of three closely related components A1, A2 and A3, which differ in their fatty acid moiety. We have investigated the influence of L-leucine and L-valine, the biosynthetic precursors of the fatty acids in A2 and A3 factors, on the complex composition and antibiotic productivity. Addition of 5 g/litre of L-leucine at the time of inoculation increases antibiotic production and improves the production of A2 factor, which represents the active principle component under clinical development. Addition of L-valine in the same conditions modifies the composition of the complex towards the A3 factor but does not improve total antibiotic productivity. A possible explanation for the different actions of the two amino acids is presented.

Marine actinomycetes as a source of novel secondary metabolites

A set of 600 actinomycetes strains which were isolated from marine sediments from various sites in the Pacific and Atlantic Oceans were screened for the production of bioactive secondary metabolites. Marine streptomycete strains were found to be producers of well known chemically diverse antibiotics isolated from terrestrial streptomycetes, as in the case of marine Micromonospora strains. New marine members of the rare genus Verrucosispora seem to be a promising source for novel bioactive secondary metabolites as shown in the case of the abyssomicin producing strain AB-18-032.

Degradation of keratin and collagen containing wastes by newly isolated thermoactinomycetes or by alkaline hydrolysis

AIMS

The aim of this study was to develop a method for microbial degradation of indigenous keratin wastes and to compare it with a method of alkaline hydrolysis.

METHODS AND RESULTS

Native sheep skin and wool were chosen as a model mixture of collagen and keratin wastes discarded by the leather and fur industries. Suitable conditions were found for hydrolysis of this mixture by four newly isolated thermoactinomycete strains. Another set of experiments was carried out using alkaline hydrolysis of keratin wastes. It was shown that microbial hydrolysates contained predominantly low molecular peptides and amino acids, including essential ones, while the alkaline hydrolysis produced predominantly peptides of higher molecular weight.

CONCLUSION

A simple and a low-cost method was proposed for rapid and effective biodegradation of keratin wastes using Thermoactinomyces strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

The proposed method could find application in agriculture for preparing mixtures containing valuable peptides and amino acids.

Non-Frankia actinomycetes isolated from surface-sterilized roots of Casuarina equisetifolia fix nitrogen

Based on partial 16S sequences, we previously described a novel group of nonsymbiotic, acetylene reduction activity-positive actinomycetes which were isolated from surface-sterilized roots of Casuarina equisetifolia growing in Mexico. An amplified rRNA restriction analysis confirmed that these actinomycetes are distinct from Frankia, a finding substantiated by a 16S rRNA gene phylogenetic analysis of two of the Mexican isolates. Further support for these actinomycetes being separate from Frankia comes from the very low DNA-DNA homology that was found. Nevertheless, the Mexican isolates may be diazotrophs based not only on their ability to grow in N-free medium and reduce acetylene to ethylene but also on the results from (15)N isotope dilution analysis and the finding that a nifH gene was PCR amplified. A comparison of the nifH sequences from the various isolates showed that they are closely related to nifH from Frankia; the similarity was 84 to 98% depending on the host specificity group. An analysis of complete 16S rRNA gene sequences demonstrated that the two strains analyzed in detail are most closely related to actinobacteria in the Thermomonosporaceae and the Micromonosporaceae.

The acbH gene of Actinoplanes sp. encodes a solute receptor with binding activities for acarbose and longer homologs

Acarbose, a pseudomaltotetraose, is produced by strains of the genus Actinoplanes and is a potent inhibitor of alpha-glucosidases, including those from the human intestine. Therefore, it is used in the treatment of patients suffering from type 2 diabetes. The benefits of acarbose for the producer are not known; however, besides acting as an inhibitor of alpha-amylases secreted by competitors, a role as a 'carbophor' has been proposed. This would require a transport system mediating its uptake into the cytoplasm of Actinoplanes sp. A putative sugar ATP binding cassette (ABC) transport system, the genes of which are included within the biosynthetic gene cluster for acarbose, was suggested to be a possible candidate. The genes acbHFG encode a possible sugar binding protein (AcbH) and two membrane integral subunits (AcbFG). A gene coding for an ATPase component is missing. Since Actinoplanes sp. cannot yet be genetically manipulated we performed experiments to identify the substrate(s) of the putative transporter by assessing the substrate specificity of AcbH. The protein was overproduced in Escherichia coli as His10-fusion protein, purified under denaturating conditions and renatured. Refolding was verified by circular dichroism spectroscopy. Surface plasmon resonance studies revealed that AcbH binds acarbose and longer derivatives, but not maltodextrins, maltose or sucrose. Immunoblot analysis revealed the association of AcbH with the membrane fraction of Actinoplanes cells that were grown in the presence of maltose, maltodextrins or acarbose. Together, these findings suggest that the AcbHFG complex might be involved in the uptake of acarbose and are consistent with a role for acarbose as a 'carbophor'.

Isolation and characterization of novel marine-derived actinomycete taxa rich in bioactive metabolites

A unique selective enrichment procedure has resulted in the isolation and identification of two new genera of marine-derived actinobacteria. Approximately 90% of the microorganisms cultured by using the presented method were from the prospective new genera, a result indicative of its high selectivity. In this study, 102 actinomycetes were isolated from subtidal marine sediments collected from the Bismarck Sea and the Solomon Sea off the coast of Papua New Guinea. A combination of physiological parameters, chemotaxonomic characteristics, distinguishing 16S rRNA gene sequences, and phylogenetic analysis based on 16S rRNA genes provided strong evidence for the two new genera (represented by strains of the PNG1 clade and strain UMM518) within the family Micromonosporaceae. Biological activity testing of fermentation products from the new marine-derived actinomycetes revealed that several had activities against multidrug-resistant gram-positive pathogens, malignant cells, and vaccinia virus replication.

Glycopeptide resistance determinants from the teicoplanin producerActinoplanes teichomyceticus

In enterococci and other pathogenic bacteria, high-level resistance to vancomycin and other glycopeptide antibiotics requires the action of the van genes, which direct the synthesis of peptidoglycan terminating in the depsipeptide D-alanyl-D-lactate, in place of the usual D-Ala-D-Ala. The Actinoplanes teichomyceticus tcp cluster, devoted to the biosynthesis of the glycopeptide antibiotic teicoplanin, contains van genes associated to a murF-like sequence (murF2). We show that A. teichomyceticus contains also a house-keeping murF1 gene, capable of complementing a temperature sensitive Escherichia coli murF mutant. MurF1, expressed in Streptomyces lividans, can catalyze the addition of either D-Ala-D-Ala or D-Ala-D-Lac to the UDP-N-acetyl-muramyl-L-Ala-D-Glu-d-Lys. However, similarly expressed MurF2 shows a small enzymatic activity only with D-Ala-D-lactate. Introduction of a single copy of the entire set of van genes confers resistance to teicoplanin-type glycopeptides to S. coelicolor.

Organization of the teicoplanin gene cluster in Actinoplanes teichomyceticus

The glycopeptide teicoplanin is used for the treatment of serious infections caused by Gram-positive pathogens. The tcp gene cluster, devoted to teicoplanin biosynthesis in the actinomycete Actinoplanes teichomyceticus, was isolated and characterized. From sequence analysis, the tcp cluster spans approximately 73 kb and includes 39 ORFs participating in teicoplanin biosynthesis, regulation, resistance and export. Of these, 34 ORFs find a match in at least one of the five glycopeptide gene clusters previously characterized. Putative roles could be assigned for most of the tcp genes. The two glycosyltransferases responsible for attaching amino sugars to amino acids 4 and 6 of the teicoplanin aglycon were overexpressed in Escherichia coli and characterized. They both recognize N-acetylglucosamine as the substrate. tGtfA can add a sugar residue in the presence or absence of N-acetylglucosamine at amino acid 4, while tGtfB can only glycosylate the teicoplanin aglycon.

Patterns of antimicrobial activities from soil actinomycetes isolated under different conditions of pH and salinity

AIMS

To evaluate the patterns of the production of antimicrobial compounds by diverse collection of actinomycetes isolated from different geographies under alternative conditions of pH and salinity in the media.

METHODS AND RESULTS

Actinomycetes were grouped based on their method of isolation and their phenotype diversity was determined by total fatty acid analysis. A total of 335 representative isolates, including 235 Streptomyces species and 100 actinomycetes from other taxa, were screened for the production of antimicrobial activities against a panel of bacteria, filamentous fungi and yeasts, including some of clinical relevance. Production of antimicrobial activities was detected in 230 strains. In the case of the genus Streptomyces, 181 antimicrobial activities (77% of the tested isolates) were recorded. The activities observed among the other actinomycetes taxa were lower (49% of the tested isolates).

CONCLUSIONS

The results of this study support the idea that species of actinomycetes isolated in alternative selective conditions of pH and salinity present a significant capacity to produce compounds with antibacterial or antifungal activity. The best group of isolates in terms of production of active secondary metabolites was the one isolated in saline conditions.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results demonstrate that these actinomycetes strains isolated in alternative selective conditions of pH and salinity and collected from diverse geographical locations present a significant capacity to produce compounds with antibacterial or antifungal activity.

Biotechnology and molecular biology of the alpha-glucosidase inhibitor acarbose

The alpha-glucosidase inhibitor acarbose, O-[4,6-dideoxy-4[1 s-(1,4,6/5)-4,5,6-trihydroxy-3-hydroxymethyl-2-cyclohexen-1-yl]-amino-alpha-D-glucopyranosyl]-(1-->4)- O-alpha-D-glucopyranosyl-(1-->4)-D-glucopyranose, is produced in large-scale fermentation by the use of strains derived from Actinoplanes sp. SE50. It has been used since 1990 in many countries in the therapy of diabetes type II, in order to enable patients to better control blood sugar contents while living with starch-containing diets. Thus, it is one of the latest successful products of bacterial secondary metabolism to be introduced into the pharmaceutical world market. Cultures of Actinoplanes sp. also produce various other acarbose-like components, of which component C is hard to separate during downstream processing, which is one of the most modern work-up processes developed to date. The physiology, genetics and enzymology of acarbose biosynthesis and metabolism in the producer have been studied to some extent, leading to the proposal of a new pathway and metabolic cycle, the "carbophore". These data could give clues for further biotechnological developments, such as the suppression of side-products, enzymological or biocombinatorial production of new metabolites and the engineering of production rates via genetic regulation in future.

Reduced Formation of Byproduct Component C in Acarbose Fermentation by Actinoplanes sp. CKD485-16

Acarbose fermentation was conducted by cultivation of Actinoplanes sp. CKD485-16. Approximately 2,300 mg/L of acarbose was produced at the end of cultivation along with 600 mg/L of the acarbose byproduct component C. Maltose, a known moiety of acarbose, should be maintained at high concentration levels in culture broths for efficient acarbose production. The acarbose yield increased with an increasing osmolality of the culture medium, with a maximum value of 3,200 mg/L obtained at 500 mOsm/kg. Component C was also produced in proportion to the osmolality. Conversion of acarbose to component C was accomplished with resting whole cells. Inhibitors of the conversion of acarbose to component C were sought since component C is probably derived from acarbose. Valienamine was found to be a potent inhibitor, resulting in a more than 90% reduction in component C formation at a 10 microM concentration. Effects were similar in a 1,500-L pilot fermentor with acarbose and component C yields of 3,490 and 43 mg/L at 500 mOsm/kg, respectively.

[Degradation of bis(2-ethylhexyl)phthalate by microorganisms of water and sediments of the Selenga river and Baikal Lake under experimental conditions]

Degradation of bis-(2-ethylhexyl)phthalate (BEHP) by microbial associations of water and bottom sediments of the Selenga River and Lake Baikal and by pure cultures of microbial species belonging to various taxa isolated from the sediments under discussion has been studied. It has been shown that intense biological degradation occurs in both water and sediments. The degrees of conversion in experimental closed systems on minimal media are 46 and 24%, respectively. The most active of the organisms studied is a Micromironospora actinomycete. It degraded BEHP by 36% of its initial concentration. Spore-forming bacteria and microorganisms of the genus Pseudomonas were less active (17-23% and 7-11%).

Longispora albida gen. nov., sp. nov., a novel genus of the family Micromonosporaceae

A novel actinomycete strain was isolated from a soil sample collected in Japan by using gellan gum as a solidifying agent. Spore-chains from the short sporophores were straight and each had more than 20 spores per chain. Spores possessed no motility. Cell-wall peptidoglycan contained meso-diaminopimelic acid, glycine, alanine and glutamic acid; whole-cell hydrolysates contained arabinose, galactose and xylose. The acyl type of the peptidoglycan was glycolyl. The predominant menaquinones were MK-10(H(4)) and MK-10(H(6)); MK-10(H(8)) was a minor component. Mycolic acids were not detected. The diagostic phospholipid was phosphatidylethanolamine. Cellular fatty acids included heptadecenoic (C(17 : 1)), 14-methylpentadecanoic (i-C(16 : 0)) and octadecenoic (C(18 : 1)) acids. The G+C content of the DNA was 70 mol%. On the basis of morphogical and chemotaxonomic properties and phylogenetic analysis based on 16S rDNA sequence data, it is proposed that this strain should be classified in a novel genus and species, Longispora albida gen. nov., sp. nov., in the family MICROMONOSPORACEAE: The type strain is K97-0003(T) (=NRRL B-24201(T)=JCM 11711(T)).

Crystal structures and structural comparison of Thermoactinomyces vulgaris R-47 alpha-amylase 1 (TVAI) at 1.6 A resolution and alpha-amylase 2 (TVAII) at 2.3 A resolution

The X-ray crystal structures of Thermoactinomyces vulgaris R-47 alpha-amylase 1 (TVAI) and alpha-amylase 2 (TVAII) have been determined at 1.6 A and 2.3 A resolution, respectively. The structures of TVAI and TVAII have been refined, R-factor of 0.182 (R(free)=0.206) and 0.179 (0.224), respectively, with good chemical geometries. Both TVAI and TVAII have four domains, N, A, B and C, and all very similar in structure. However, there are some differences in the structures between them. Domain N of TVAI interacts strongly with domains A and B, giving a spherical shape structure to the enzyme, while domain N of TVAII is isolated from the other domains, which leads to the formation of a dimer. TVAI has three bound Ca ions, whereas TVAII has only one. TVAI has eight extra loops compared to TVAII, while TVAII has two extra loops compared to TVAI. TVAI can hydrolyze substrates more efficiently than TVAII with a high molecular mass such as starch, while TVAII is much more active against cyclodextrins than TVAI and other alpha-amylases. A structural comparison of the active sites has clearly revealed this difference in substrate specificity.