Antibiotics production by an actinomycete isolated from the termite gut.

As well as the search for new antibiotics, a new resource or strains for the known antibiotics is also important. Microbial symbionts in the gut of termites could be regarded as one of the feasible resource for such purpose. In this study, antibiotic-producing actinomycetes were screened from symbionts of the termite gut. 16SrRNA sequence analysis for the 10 isolates revealed that they belong to actinomycetes such as Streptomyces sp., Kitasatospora sp., and Mycobacterium sp. A culture broth from one of the isolate, namely strain CA1, belonging to the genera Streptomyces exhibited antagonistic activity against actinomycetes (Micrococcus spp.), gram-positive bacteria (Bacillus spp.), and yeast (Candida spp.). The structures of 2 compounds isolated from the culture broth of the strain CA1 were identified as those of actinomycin X2 and its analog, D. This study is the first to report that some symbionts of the termite gut are antibiotic-producing actinomycetes, and suggest that the termite gut is a feasible resource for bioprospecting.

Application of random amplified polymorphic DNA (RAPD) analysis coupled with microchip electrophoresis for high-resolution identification of Monascus strains.

Monascus fungi are commonly used for a variety of food products in Asia, and are also known to produce some biologically active compounds. Since the use of Monascus is expected to increase in food industries, strain-level identification and management of Monascus will be needed in the near future. In the present study, random amplified polymorphic DNA (RAPD) analysis coupled with microchip electrophoresis was applied for this purpose. Evaluations of the analysis stability revealed that reproducible results could be obtained, although template DNA fragmentation could influence the resulting RAPD pattern. RAPD analysis using 15 Monascus strains consisting of four species, M. ruber, M. pilosus, M. purpureus, and M. kaoliang showed that each strain generated a unique RAPD pattern, which allows strain-level identification of Monascus. In addition, the phylogenetic tree constructed from RAPD patterns reflected M. ruber-M. pilosus and M. purpureus-M. kaoliang clusters inferred from both ITS and beta-tubulin gene sequences, which indicated that the RAPD pattern could reflect their phylogenetic traits to a certain extent. On the other hand, RAPD analysis did not support the monophyletic clustering of the four Monascus species used in this study, which suggests the necessity of reexamination of species boundaries in Monascus.

Optimized culture conditions for the efficient production of porcine adenylate kinase in recombinant Escherichia coli.

Temperature shift cultivations with amino acid supplementation were optimized to produce porcine adenylate kinase (ADK) in recombinant Escherichia coli harboring a pUC-based recombinant plasmid under the control of the trp promoter. With regard to temperature control, the culture condition was initially maintained at 35 degrees C for cellular growth, but ADK expression was suppressed until the late logarithmic growth phase; subsequently, a temperature shift was applied (from 35 degrees C to 42 degrees C), which resulted in maximal ADK production. In addition, supplementation of amino acids, especially valine and leucine, during the temperature shift stimulated ADK expression from 3.5% to 9.2% and 8.6% of the total protein, respectively. After optimization, 1 g ADK per liter was produced within 16 h of cultivation with a dry cell weight of 21.8 g/l. In this system, there was no loss of the recombinant plasmid during cultivation without selective pressure.

Biodegradation of thiodiglycol, a hydrolyzate of the chemical weapon Yperite, by benzothiophene-desulfurizing bacteria.

Microbial degradation of thiodiglycol (bis(2-hydroxyethyl)sulfide, TDG) with petroleum-desulfurizing soil bacteria was examined. Among the bacteria tested, several strains belonging to the genera Rhodococcus and Gordonia grew on TDG as the sole sulfur source. The selected strain Rhodococcus sp. strain T09, which was re-identified as R. jostii, showed TDG degradation activity only when grown in the presence of TDG as the sole sulfur source. Repeat batch degradation of TDG by using strain T09 could be continued for over 50h, with a slight loss of activity.

Stereospecific degradation of phenylsuccinate by actinomycetes.

Racemic phenylsuccinate was stereospecifically degraded by the actinomycetes PS9 and PS17 isolated from soil obtained from Okinawa Island, Japan. Strain PS9, identified as a Citricoccus sp., preferentially degraded the R-form, while strain PS17, identified as a Microbacterium sp., preferentially degraded the S-form of phenylsuccinate. Analysis of the culture broths of these species with phenylsuccinate as the sole carbon source revealed that benzoic acid was produced as a metabolic intermediate. Benzoic acid was further degraded by strain PS9 with m- and/or p-hydroxybenzoic acid but not o-hydroxybenzoic acid as possible intermediates.

Red yeast rice fermentation by selected Monascus sp. with deep-red color, lovastatin production but no citrinin, and effect of temperature-shift cultivation on lovastatin production.

Monascus pilosus NBRC4520 was selected for functional fermented food inoculation for its high lovastatin and low citrinin production with a deep-red color. For koji (mold rice) with high lovastatin production, separation of the growth phase and lovastatin production phase by shifting the temperature from 30 to 23 degrees C increased lovastatin production by nearly 20 times compared to temperature-constant cultivation. In addition, citrinin was not produced even in the lovastatin production phase, although the pigment was increased. With temperature-shift cultivation, 225 microg lovastatin/g dry koji was produced in 14 days without citrinin.