Statistical optimization and sequential scale-up of α-galactosidase production by Actinoplanes utahensis B1 from shake flask to pilot scale

α-Galactosidase (α-GAL) is a class of hydrolase that releases galactose from galacto-oligosaccharides and synthetic substrates such as pNPG. In this study, the production of α-GAL by Actinoplanes utahensis B1 in submerged fermentation was enhanced by using statistical methods. The effects of temperature, pH, and inoculum percentage on enzyme secretion were optimized using BBD of RSM. The optimized process was scaled up from the shake flask to the laboratory scale (5 L) and to pilot scale (30 L) using KLa based scale-up strategy. By using BBD, a maximum yield of 62.5 U/mL was obtained at a temperature of 28 °C, a pH of 6.9, and an inoculum of 6.4%. Scale-up was performed successfully and achieved a yield of 74.4 U/mL and 76.8 U/mL in laboratory scale and pilot scale fermenters. The TOST was performed to validate the scale-up strategy and the results showed a confidence level of 95% for both scales indicating the perfect execution of scale-up procedure. Through the implementation of BBD and scale-up strategy, the overall enzyme yield has been significantly increased to 76%. This is the first article to explore the scale-up of α-GAL from the A. utahensis B1 strain and provide valuable insights for industrial applications.

Structure and Candidate Biosynthetic Gene Cluster of a Manumycin-Type Metabolite from Salinispora pacifica

A new manumycin-type natural product named pacificamide (1) and its candidate biosynthetic gene cluster (pac) were discovered from the marine actinobacterium Salinispora pacifica CNT-855. The structure of the compound was determined using NMR, electronic circular dichroism, and bioinformatic predictions. The pac gene cluster is unique to S. pacifica and found in only two of the 119 Salinispora genomes analyzed across nine species. Comparative analyses of biosynthetic gene clusters encoding the production of related manumycin-type compounds revealed genetic differences in accordance with the unique pacificamide structure. Further queries of manumycin-type gene clusters from public databases revealed their limited distribution across the phylum Actinobacteria and orphan diversity that suggests additional products remain to be discovered in this compound class. Production of the known metabolite triacsin D is also reported for the first time from the genus Salinispora. This study adds two classes of compounds to the natural product collective isolated from the genus Salinispora, which has proven to be a useful model for natural product research.

Verrucosamide, a Cytotoxic 1,4-Thiazepane-Containing Thiodepsipeptide from a Marine-Derived Actinomycete

A new cytotoxic thiodepsipeptide, verrucosamide (1), was isolated along with the known, related cyclic peptide thiocoraline, from the extract of a marine-derived actinomycete, a Verrucosispora sp., our strain CNX-026. The new peptide, which is composed of two rare seven-membered 1,4-thiazepane rings, was elucidated by a combination of spectral methods and the absolute configuration was determined by a single X-ray diffraction study. Verrucosamide (1) showed moderate cytotoxicity and selectivity in the NCI 60 cell line bioassay. The most susceptible cell lines were MDA-MB-468 breast carcinoma with an LD₅₀ of 1.26 µM, and COLO 205 colon adenocarcinoma with an LD₅₀ of 1.4 µM. Also isolated along with verrucosamide were three small 3-hydroxy(alkoxy)-quinaldic acid derivatives that appear to be products of the same biosynthetic pathway.

Extending the Salinilactone Family

Five new members of the salinilactone family, salinilactones D-H, are reported. These bicyclic lactones are produced by Salinispora bacteria and display extended or shortened alkyl side chains relative to the recently reported salinilactones A-C. They were identified by GC/MS, gas chromatographic retention index, and comparison with synthetic samples. We further investigated the occurrence of salinilactones across six newly proposed Salinispora species to gain insight into how compound production varies among taxa. The growth-inhibiting effect of this compound family on multiple biological systems including non-Salinispora actinomycetes was analyzed. Additionally, we found strong evidence for significant cytotoxicity of the title compounds.

Detection of Natural Products and Their Producers in Ocean Sediments

Thousands of natural products have been identified from cultured microorganisms, yet evidence of their production in the environment has proven elusive. Technological advances in mass spectrometry, combined with public databases, now make it possible to address this disparity by detecting compounds directly from environmental samples. Here, we used adsorbent resins, tandem mass spectrometry, and next-generation sequencing to assess the metabolome of marine sediments and its relationship to bacterial community structure. We identified natural products previously reported from cultured bacteria, providing evidence they are produced in situ, and compounds of anthropogenic origin, suggesting this approach can be used as an indicator of environmental impact. The bacterial metabolite staurosporine was quantified and shown to reach physiologically relevant concentrations, indicating that it may influence sediment community structure. Staurosporine concentrations were correlated with the relative abundance of the staurosporine-producing bacterial genus Salinispora and production confirmed in strains cultured from the same location, providing a link between compound and candidate producer. Metagenomic analyses revealed numerous biosynthetic gene clusters related to indolocarbazole biosynthesis, providing evidence for noncanonical sources of staurosporine and a path forward to assess the relationships between natural products and the organisms that produce them. Untargeted environmental metabolomics circumvents the need for laboratory cultivation and represents a promising approach to understanding the functional roles of natural products in shaping microbial community structure in marine sediments.IMPORTANCE Natural products are readily isolated from cultured bacteria and exploited for useful purposes, including drug discovery. However, these compounds are rarely detected in the environments from which the bacteria are obtained, thus limiting our understanding of their ecological significance. Here, we used environmental metabolomics to directly assess chemical diversity in marine sediments. We identified numerous metabolites and, in one case, isolated strains of bacteria capable of producing one of the compounds detected. Coupling environmental metabolomics with community and metagenomic analyses provides opportunities to link compounds and producers and begin to assess the complex interactions mediated by specialized metabolites in marine sediments.

Catenulobactins A and B, Heterocyclic Peptides from Culturing Catenuloplanes sp. with a Mycolic Acid-Containing Bacterium

The production of two new heterocyclic peptide isomers, catenulobactins A (1) and B (2), in cultures of Catenuloplanes sp. RD067331 was significantly increased when it was cocultured with a mycolic acid-containing bacterium. The planar structures and absolute configurations of the catenulobactins were determined based on NMR/MS and chiral-phase GC-MS analyses. Catenulobactin B (2) displayed Fe(III)-chelating activity and moderate cytotoxicity against P388 murine leukemia cells.

The role of inter-species interactions in Salinispora specialized metabolism

Bacterial genome sequences consistently contain many more biosynthetic gene clusters encoding specialized metabolites than predicted by the compounds discovered from the respective strains. One hypothesis invoked to explain the cryptic nature of these gene clusters is that standard laboratory conditions do not provide the environmental cues needed to trigger gene expression. A potential source of such cues is other members of the bacterial community, which are logical targets for competitive interactions. In this study, we examined the effects of such interactions on specialized metabolism in the marine actinomycete Salinispora tropica. The results show that antibiotic activities and the concentration of some small molecules increase in the presence of co-occurring bacterial strains relative to monocultures. Some increases in antibiotic activity could be linked to nutrient depletion by the competitor as opposed to the production of a chemical cue. Other increases were correlated with the production of specific compounds by S. tropica. In particular, one interaction with a Vibrio sp. consistently induced antibiotic activity and was associated with parent ions that were unique to this interaction, although the associated compound could not be identified. This study provides insight into the metabolomic complexities of bacterial interactions and baseline information for future genome mining efforts.

Nitrogen-Containing Volatiles from Marine Salinispora pacifica and Roseobacter-Group Bacteria

Bacteria can produce a wide variety of volatile compounds. Many of these volatiles carry oxygen, while nitrogen-containing volatiles are less frequently observed. We report here on the identification and synthesis of new nitrogen-containing volatiles from Salinispora pacifica CNS863 and explore the occurrence in another bacterial lineage, exemplified by Roseobacter-group bacteria. Several compound classes not reported before from bacteria were identified, such as dialkyl ureas and oxalamides. Sulfinamides have not been reported before as natural products. The actinomycete S. pacifica CNS863 produces, for example, sulfinamides N-isobutyl- and N-isopentylmethanesulfinamide (5, 6), urea N,N'-diisobutylurea (16), and oxalamide N,N'-diisobutyloxalamide (17). In addition, new imines such as (E)-1-(furan-2-yl)-N-(2-methylbutyl)methanimine (8) and (E)-2-((isobutylimino)methyl)phenol (13) were identified together with several other imines, acetamides, and formamides. Some of these compounds including the sulfinamides were also released by the Roseobacter-group bacteria Roseovarius pelophilus G5II, Pseudoruegeria sp. SK021, and Phaeobacter gallaeciensis BS107, although generally fewer compounds were detected. These nitrogen-containing volatiles seem to originate from biogenic amines derived from the amino acids valine, leucine, and isoleucine.

Structural and dynamic characterization of a freestanding acyl carrier protein involved in the biosynthesis of cyclic lipopeptide antibiotics

Friulimicin is a cyclic lipodecapeptide antibiotic that is produced by Actinoplanes friuliensis. Similar to the related lipopeptide drug daptomycin, the peptide skeleton of friulimicin is synthesized by a large multienzyme nonribosomal peptide synthetase (NRPS) system. The LipD protein plays a major role in the acylation reaction of friulimicin. The attachment of the fatty acid group promotes its antibiotic activity. Phylogenetic analysis reveals that LipD is most closely related to other freestanding acyl carrier proteins (ACPs), for which the genes are located near to NRPS gene clusters. Here, we report that the solution NMR structure of apo-LipD is very similar to other four-helix bundle forming ACPs from fatty acid synthase (FAS), polyketide synthase, and NRPS systems. By recording NMR dynamics data, we found that the backbone motions in holo-LipD are more restricted than in apo-LipD due to the attachment of phosphopantetheine moiety. This enhanced stability of holo-LipD was also observed in differential scanning calorimetry experiments. Furthermore, we demonstrate that, unlike several other ACPs, the folding of LipD does not depend on the presence of divalent cations, although the presence of Mg2+ or Ca2+ can increase the protein stability. We propose that small structural rearrangements in the tertiary structure of holo-LipD which lead to the enhanced stability are important for the cognate enzyme recognition for the acylation reaction. Our results also highlight the different surface charges of LipD and FAS-ACP from A. friuliensis that would allow the acyl-CoA ligase to interact preferentially with the LipD instead of binding to the FAS-ACP.

Genome improvement of the acarbose producer Actinoplanes sp. SE50/110 and annotation refinement based on RNA-seq analysis

Actinoplanes sp. SE50/110 is the natural producer of acarbose, which is used in the treatment of diabetes mellitus type II. However, until now the transcriptional organization and regulation of the acarbose biosynthesis are only understood rudimentarily. The genome sequence of Actinoplanes sp. SE50/110 was known before, but was resequenced in this study to remove assembly artifacts and incorrect base callings. The annotation of the genome was refined in a multi-step approach, including modern bioinformatic pipelines, transcriptome and proteome data. A whole transcriptome RNA-seq library as well as an RNA-seq library enriched for primary 5'-ends were used for the detection of transcription start sites, to correct tRNA predictions, to identify novel transcripts like small RNAs and to improve the annotation through the correction of falsely annotated translation start sites. The transcriptome data sets were also applied to identify 31 cis-regulatory RNA structures, such as riboswitches or RNA thermometers as well as three leaderless transcribed short peptides found in putative attenuators upstream of genes for amino acid biosynthesis. The transcriptional organization of the acarbose biosynthetic gene cluster was elucidated in detail and fourteen novel biosynthetic gene clusters were suggested. The accurate genome sequence and precise annotation of the Actinoplanes sp. SE50/110 genome will be the foundation for future genetic engineering and systems biology studies.

Replacement of Soybean Meal with Animal Origin Protein Meals Improved Ramoplanin A2 Production by Actinoplanes sp. ATCC 33076

Ramoplanin A2 is the last resort antibiotic for treatment of many high morbidity- and mortality-rated hospital infections, and it is expected to be marketed in the forthcoming years. Therefore, high-yield production of ramoplanin A2 gains importance. In this study, meat-bone meal, poultry meal, and fish meal were used instead of soybean meal for ramoplanin A2 production by Actinoplanes sp. ATCC 33076. All animal origin nitrogen sources stimulated specific productivity. Ramoplanin A2 levels were determined as 406.805 mg L(-1) in fish meal medium and 374.218 mg L(-1) in poultry meal medium. These levels were 4.25- and 4.09-fold of basal medium, respectively. However, the total yield of poultry meal was higher than that of fish meal, which is also low-priced. In addition, the variations in pH levels, protein levels, reducing sugar levels, extracellular protease, amylase and lipase activities, and intracellular free amino acid levels were monitored during the incubation period. The correlations between ramoplanin production and these variables with respect to the incubation period were determined. The intracellular levels of L-Phe, D-Orn, and L-Leu were found critical for ramoplanin A2 production. The strategy of using animal origin nitrogen sources can be applied for large-scale ramoplanin A2 production.

Metabolic differences of industrial acarbose-producing Actinoplanes sp. A56 under various osmolality levels

Many investigations have revealed that a certain concentration of osmolality was indispensable for efficient acarbose production, but little information was available on the response mechanism of acarbose-producing strains to osmotic stress. By using the gas chromatography-mass spectrometry (GC-MS) analysis coupled with the enzyme activity determination of central carbon metabolism, the present work investigated the metabolic characteristics of industrial acarbose-producing Actinoplanes sp. A56 under various osmolality levels. Relatively high osmolality (450-500 mOsm/kg) appeared to favor efficient acarbose production by Actinoplanes sp. A56, although it inhibited cell growth. Further GC-MS analysis showed that fatty acids were the uppermost differential intracellular metabolites under various osmolality levels, and the relatively high osmolality resulted in increases in levels of fatty acids.

Comparative analysis of rapamycin biosynthesis clusters between Actinoplanes sp. N902-109 and Streptomyces hygroscopicus ATCC29253

The present study was designed to identify the difference between two rapamycin biosynthetic gene clusters from Streptomyces hygroscopicus ATCC29253 and Actinoplanes sp. N902-109 by comparing the sequence and organization of the gene clusters. The biosynthetic gene cluster for rapamycin in Streptomyces hygroscopicus ATCC29253 was reported in 1995. The second rapamycin producer, Actinoplanes sp. N902-109, which was isolated in 1995, could produce more rapamycin than Streptomyces hygroscopicus ATCC29253. The genomic map of Actinoplanes sp. N902-109 has been elucidated in our laboratory. Two gene clusters were compared using the online software anti-SMASH, Glimmer 3.02 and Subsystem Technology (RAST). Comparative analysis revealed that the organization of the multifunctional polyketide synthases (PKS) genes: RapA, RapB, RapC, and NRPS-like RapP were identical in the two clusters. The genes responsible for precursor synthesis and macrolactone modification flanked the PKS core region in N902-109, while the homologs of those genes located downstream of the PKS core region in ATCC29253. Besides, no homolog of the gene encoding a putative type II thioesterase that may serve as a PKS "editing" enzyme accounted for over-production of rapamycin in N902-109, was found in ATCC29253. Furthermore, no homologs of genes rapQ (encoding a methyltransferase) and rapG in N902-109 were found in ATCC29253, however, an extra rapM gene encoding methyltransferase was discovered in ATCC29253. Two rapamycin biosynthetic gene clusters displayed overall high homology as well as some differences in gene organization and functions.

Molecular networking and pattern-based genome mining improves discovery of biosynthetic gene clusters and their products from Salinispora species

Genome sequencing has revealed that bacteria contain many more biosynthetic gene clusters than predicted based on the number of secondary metabolites discovered to date. While this biosynthetic reservoir has fostered interest in new tools for natural product discovery, there remains a gap between gene cluster detection and compound discovery. Here we apply molecular networking and the new concept of pattern-based genome mining to 35 Salinispora strains, including 30 for which draft genome sequences were either available or obtained for this study. The results provide a method to simultaneously compare large numbers of complex microbial extracts, which facilitated the identification of media components, known compounds and their derivatives, and new compounds that could be prioritized for structure elucidation. These efforts revealed considerable metabolite diversity and led to several molecular family-gene cluster pairings, of which the quinomycin-type depsipeptide retimycin A was characterized and linked to gene cluster NRPS40 using pattern-based bioinformatic approaches.

The pathway-specific regulatory genes, tei15* and tei16*, are the master switches of teicoplanin production in Actinoplanes teichomyceticus

Pathogenic antibiotic-resistant bacteria are an unprecedented threat to health care worldwide. The range of antibiotics active against these bacteria is narrow; it includes teicoplanin, a "last resort" drug, which is produced by the filamentous actinomycete Actinoplanes teichomyceticus. In this report, we determine the functions of tei15* and tei16*, pathway-specific regulatory genes that code for StrR- and LuxR-type transcriptional factors, respectively. The products of these genes are master switches of teicoplanin biosynthesis, since their inactivation completely abolished antibiotic production. We show that Tei15* positively regulates the transcription of at least 17 genes in the cluster, whereas the targets of Tei16* still remain unknown. Integration of tei15* or tei16* under the control of the aminoglycoside resistance gene aac(3)IV promoter into attBϕC31 site of the A. teichomyceticus chromosome increased teicoplanin productivity to nearly 1 g/L in TM1 industrial medium. The expression of these genes from the moderate copy number episomal vector pKC1139 led to 3-4 g/L teicoplanin, while under the same conditions, wild type produced approximately 100 mg/L. This shows that a significant increase in teicoplanin production can be achieved by a single step of genetic manipulation of the wild-type strain by increasing the expression of the tei regulatory genes. This confirms that natural product yields can be increased using rational engineering once suitable genetic tools have been developed. We propose that this new technology for teicoplanin overproduction might now be transferred to industrial mutants of A. teichomyceticus.

Synthesis of the Racemate of the Stereoisomer at C-6a of BE-40644, a Bioactive Metabolite of Actinoplanes sp. with a Sesquiterpene-substituted p-Benzoquinone Structure

BE-40644 is a tetracyclic metabolite of Actinoplanes sp. A 40644 possessing a sesquiterpene-substituted p-benzoquinone structure with cis-fused B/C ring stereochemistry that inhibits the human thioredoxin system as the well as the growth of several cancer cell lines. Its B/C trans-fused stereoisomer at C-6a was synthesized as a racemate starting from geranylacetone and 3,5-dihydroxybenzoic acid.

Discovering the recondite secondary metabolome spectrum of Salinispora species: a study of inter-species diversity

Patterns of inter-species secondary metabolite production by bacteria can provide valuable information relating to species ecology and evolution. The complex nature of this chemical diversity has previously been probed via directed analyses of a small number of compounds, identified through targeted assays rather than more comprehensive biochemical profiling approaches such as metabolomics. Insights into ecological and evolutionary relationships within bacterial genera can be derived through comparative analysis of broader secondary metabolite patterns, and this can also eventually assist biodiscovery search strategies for new natural products. Here, we investigated the species-level chemical diversity of the two marine actinobacterial species Salinispora arenicola and Salinispora pacifica, isolated from sponges distributed across the Great Barrier Reef (GBR), via their secondary metabolite profiles using LC-MS-based metabolomics. The chemical profiles of these two species were obtained by UHPLC-QToF-MS based metabolic profiling. The resultant data were interrogated using multivariate data analysis methods to compare their (bio)chemical profiles. We found a high level of inter-species diversity in strains from these two bacterial species. We also found rifamycins and saliniketals were produced exclusively by S. arenicola species, as the main secondary metabolites differentiating the two species. Furthermore, the discovery of 57 candidate compounds greatly increases the small number of secondary metabolites previously known to be produced by these species. In addition, we report the production of rifamycin O and W, a key group of ansamycin compounds, in S. arenicola for the first time. Species of the marine actinobacteria harbour a much wider spectrum of secondary metabolites than suspected, and this knowledge may prove a rich field for biodiscovery as well as a database for understanding relationships between speciation, evolution and chemical ecology.

Crystallographic study of the interaction of the anti-HIV lectin actinohivin with the α(1-2)mannobiose moiety of gp120 HMTG

Actinohivin (AH) is a new potent anti-HIV lectin of microbial origin. In order to modify it to produce a more efficient drug, its three-dimensional structure has previously been determined with and without the target α(1-2)mannobiose moiety of the high-mannose-type glycan (HMTG) attached to HIV-1 gp120. However, ambiguity remained in the structures owing to packing disorder that was possibly associated with peptide fragments attached at the N-terminus. To resolve these problems, the duration of cultivation of the AH-producing strain was examined and it was found that in a sample obtained from a 20 d culture the heterogeneous fragments were completely removed to produce mature AH with high homogeneity. In addition, the purification procedures were simplified in order to increase the yield of AH and the addition of solvents was also examined in order to increase the solubility of AH. AH thus obtained was successfully crystallized with high reproducibility in a different form to the previously obtained crystals. The crystal diffracted well to beyond 1.90 Å resolution and the crystallographic data suggested that it contained no packing disorder.

An optimized industrial fermentation processes for acarbose production by Actinoplanes sp. A56

Acarbose, a competitive α-glucosidase inhibitor, is clinically and widely used in the treatment of type II diabetes mellitus. In order to improve the industrial acarbose productivity by Actinoplanes sp. A56, the classical fermentation conditions such as total sugar concentration in broths, pH value and dissolved oxygen (DO) level were systematically investigated in a 30000-l fermenter, respectively. It was observed that a high-concentration total sugar (75-80 g/l), 7.0-7.2 of pH value and 40-50% of DO concentration were favorable for acarbose production. As a result, the final acarbose yield was elevated to approximately 5000 mg/l at 168 h of fermentation.

[Genetic manipulation system for tiacumicin producer Dactylosporangium aurantiacum NRRL 18085]

OBJECTIVE

To optimize the production of tiacumicin B in Dactylosporangium aurantiacum NRRL 18085, we developed a genetic manipulation system for disrupting genes involved in tiacumicin biosynthesis.

METHODS

We developed a method of conjugation to transfer exotic DNA pSET152 into D. aurantiacum NRRL 18085. Using the PCR-targeting system, we disrupted a putative tiacumicin halogenase gene in vitro by "in-frame deletion" in E. coli, and then the resulting cosmid was transferred into D. aurantiacum NRRL 18085 by conjugation.

RESULTS

The putative tiacumicin halogenase gene in D. aurantiacum NRRL 18085 was disrupted by in-frame deletion from a double-crossover recombination event. The resulting mutant strain lost the ability to produce tiacumicin B.

CONCLUSION

We developed a genetic manipulation system for D. aurantiacum NRRL 18085, enabling the functional characterization of tiacumicin biosynthetic genes in vivo, and we offered a positive example for other Actinobacteria lacking an appropriate genetic manipulation system.

Isolation and identification of chlorinated genistein from Actinoplanes sp. HBDN08 with antioxidant and antitumor activities

A strain Actinoplanes sp. HBDN08 was screened by PCR-guided method using primers derived from conserved regions of halogenase genes. A new chlorinated isoflavone, 3',8-dichlorogenistein (1), along with 8-chlorogenistein (2) were isolated from the fermentation broth of Actinoplanes sp. HBDN08. Their structures were elucidated on the basis of extensive 1D and 2D NMR as well as HRESI-MS, ESI-MS, UV, and IR spectroscopic analyses. The origin of the two compounds was also investigated by high-performance liquid chromatography (HPLC) analysis. The results demonstrated that they were not biosynthesized but derived from the biotransformation of genistein by Actinoplanes sp. HBDN08. The antioxidant activities of the isolated compounds 1 and 2 were evaluated by using the lipid peroxidation assay. Their antitumor activities were calculated according to the inhibitory rate of cell proliferation against the human breast cancer cell line MDA-MB-231. The results indicated that compounds 1 (IC(50) = 5.2 microM) and 2 (IC(50) = 7.5 microM) showed stronger antioxidant activities than genistein (IC(50) = 13.6 microM). In comparison with the antitumor activities of genistein, those of compounds 1 and 2 increased 7.7- and 2.6-fold, respectively. These results suggest that the PCR-guided screening strategy is a rapid method for obtaining halometabolite-producing strains. Moreover, these results reveal that chlorination has significant effects on the bioactivities of genistein. This could be important information for studying the structure-activity relationships of genistein.

Glycerol affects the acyl moieties of teicoplanin components produced by Actinoplanes teichomyceticus MSl2210

Teicoplanin, a glycopeptide antibiotic, is composed of five main components, denoted T-A2-1 to T-A2-5. We investigated the use of glycerol as a carbon source affecting the teicoplanin components and its acyl moieties. As a result, we show the change of teicoplanin components, as well as an increase of total teicoplanin yields, caused by the addition of glycerol to the production medium. Analysis of the total cell lipids upon the addition of glycerol also showed a corresponding change in the proportion of teicoplanin, suggesting that glycerol strongly affects a change of teicoplanin branched acyl moieties.

Degradation of rutin by Thermoactinomyces vulgaris and other thermophilic compost isolates

The mutagenic effects of rutin and quercetin have aroused the interest of many investigators. To develop the microbial degradation of rutin, a thermophilic actinomycete, which could hydrolyze rutin, was isolated from compost soil. The taxonomical characteristics of this thermophilic actinomycete were examined and identified as Thermoactinomyces vulgaris PU18-2. After cultivation of T. vulgaris PU18-2 in the rutin-CYC medium for 60 h, the culture filtrate had a rutin-degrading ability, but the cell-free extract did not. There was no quercetin, rutinose, rhamnose, and glucose accumulated in the rutin hydrolysate of the culture filtrate. Both alpha-rhamnosidase and beta-glucosidase activities were not found in the culture filtrate of the T. vulgaris PU18-2 in the rutin-CYC medium. These results showed that the initial attack on rutin by the extracellular enzymes of T. vulgaris PU18-2 apparently was not through the glycosidase-mediated hydrolysis of glycosidic bond.

Stabilization effect of resin on the production of potent proteasome inhibitor NPI-0052 during submerged fermentation of Salinispora tropica

Addition of acrylic resin Amberlite XAD-7 during the fermentation of Salinispora tropica significantly enhanced the production of NPI-0052 by 69 fold. Examination of the time course of resin addition to the Salinispora tropica fermentation demonstrated that the increase in the production of NPI-052 is due to the stabilization effect by resin but not the removal of an end product feedback repression. Delay in resin addition to the fermentation led to decreases in the production of NPI-0052 to the amounts that are synthesized prior to the resin addition.