The type III secretion system (T3SS) is highly conserved in many Gram-negative pathogenic bacteria and functions as an injector of bacterial proteins (effectors) into host cells. T3SSs are involved in establishing disease processes, but this machinery is not essential for bacterial growth or homeostasis. Thus, T3SS is expected to be a candidate therapeutic target, and inhibitors of T3SSs could potentially reduce virulence without causing bacterial death, thereby avoiding any subsequent development of resistance. We identified a linear polyketide compound, aurodox, as a specific T3SS inhibitor from the culture broth of Streptomyces sp. using a screening system for the T3SS-mediated hemolysis of enteropathogenic Escherichia coli (EPEC) established by our group. Aurodox strongly inhibited T3SS-mediated hemolysis with an IC 50 value of 1.5 lg ml À1 without affecting bacterial growth in liquid media. We also demonstrated that aurodox specifically inhibits the secretion of type IIIsecreted proteins such as EspB, EspF and Map, without affecting the expression of the housekeeping protein GroEL. Furthermore, an in vivo infection study using mice clearly indicated that the administration of aurodox allowed the mice to survive a lethal dose of Citrobactor rodentium, a model bacterium for human pathogens such as EPEC. Thus, our in vivo study directly demonstrated for the first time that this putative T3SS inhibitor can be applied as a novel class of anti-infective agents.

Endophytic actinomycetes associated with plant roots are a relatively untapped source of potential new bioactive compounds. This is becoming increasingly important, as the returns from discovery research on soil-dwelling microbes, have been continuously diminishing. We have isolated more than 1000 strains of actinomycetes from plant roots in our search for novel bioactive compounds, identified and assayed their bioactive metabolites, as well as investigated their biosynthetic genes for generating secondary metabolites. This has resulted in the discovery of several interesting compounds. Creation of plant root clone libraries enabled us to confirm that we had, indeed, isolated endophytes. In this paper, we introduce our approach to this promising line of research, incorporating data from other publications, and illustrate the potential that endophytic actinomycetes offer as a new source of novel lead compounds.

CHLOROPEPTINS I AND II, NOVEL INHIBITORS AGAINST gpl20-CD4 BINDING FROM Streptomyces sp. Sir: Recently, we reported the first gpl20-CD4 binding inhibitors of microbial origin, isochromophilones I and II, produced by Penicillium sp.1}. Now, we report additional two gpl20-CD4 binding inhibitors, chloropeptins 1(1) and ll(2) (Fig. 1), produced by a soil actinomycete, Streptomyces sp. WK-3419. The major component 1 is a new compound, while the other one 2 was identified with complestatin2) which has been reported to inhibit the hemolysis of erythrocytes sensitized by the complement system3). This communication deals with the fermentation, isolation, characterization

During our search for new antiprotozoal (antimalarial and antitrypanosomal) agents, we have tested culture extracts of soil microorganisms from a variety of sources, including those isolated by the Kitasato Institute for Life Sciences and the Bioresource Laboratories, MicroBiopharm Japan Corporation. We have previously discovered a variety of microbial metabolites exhibiting antiprotozoal, 1,2 antimalarial 3,4 and antitrypanosomal properties. 5,6 Recently, we have isolated a new derivative of pactamycin, designated as jogyamycin (Figure 1), from a culture broth of Streptomyces sp. a-WM-JG-16.2. This compound has proved to have potent antiprotozoal activity (Table 2). Here, we report the fermentation, isolation, structure elucidation and biological activity of this novel aminocyclopentitol antibiotic.The producing organism, strain a-WM-JG-16.2 was isolated from a soil sample collected in Jogjakarta, Indonesia, using the sucrose density gradient centrifugation method. 7 Using the basic local alignment search tool (BLAST), we compared the 16S rRNA gene sequences available in the EzTaxon server to identify the species of strain a-WM-JG-16.2. Streptomyces sp. a-WM-JG-16.2 was classified as a species of the genus Streptomyces; the 16S rRNA gene sequence comparison showing a 100% similarity with S. griseoruber NBRC12873 (AB184209).The strain was cultured on a rotary shaker (220 r.p.m.) at 28 1C for 5 days in 500-ml Erlenmeyer flasks (20 flasks) containing 50 ml of a production medium containing 2% rice starch (Rose brand, Cikampek, Indonesia), 2% glucose (Univar, Sydney, NSW, Australia), 2% soybean meal (J-Oil Mills, Tokyo, Japan), 0.5% yeast extract

Two anti-mycobacterial peptides with a lasso structure, named lariatins A and B, were separated by HP-20 and ODS column chromatographies and purified by HPLC from the culture broth of Rhodococcus jostii K01-B0171, which was isolated from soil aggregates collected in Yunnan, China. Lariains A and B showed growth inhibition against Mycobacterium smegmatis with MIC values of 3.13 and 6.25 m g/ml in agar dilution method, respectively. Furthermore, lariatin A inhibited the growth of Mycobacterium tuberculosis with an MIC of 0.39 mg/ml in liquid microdilution method.Keywords lariatin A, lariatin B, lasso structure, antimycobacterial peptide, tuberculosis, Rhodococcus jostii, soil aggregates IntroductionOur research group has focused on discovery of antiinfectives from microbial metabolites [1ϳ3]. Tuberculosis (TB) is still the greatest single infectious cause of mortality in the world, together with HIV and malaria [4]. Moreover, the spread of the HIV promoted to increase the number of tuberculosis patients [5]. However, powerful anti-TB drugs with a new mechanism of action have not been developed in last over thirty years, and only 5 anti-TB drugs can be clinically used still now. Since isoniazid and ethambutol, first-line anti-TB drugs, show specific inhibition against Mycobacteria, we have screened for new agents from microbial metabolites having specific inhibition against Mycobacterium smegmatis among 16 test microorganisms including Gram-positive and -negative bacteria, fungi and yeasts. As a part of this program, we discovered novel

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Three novel antitrypanosomal alkaloids, named spoxazomicins A-C, were isolated by silica gel column chromatography and HPLC from the culture broth of a new endophytic actinomycete species, Streptosporangium oxazolinicum K07-0460 T . The structures of the spoxazomicins were elucidated by NMR and X-ray crystal analyses and shown to be new types of pyochelin family antibiotic. Spoxazomicin A showed potent and selective antitrypanosomal activity with an IC 50 value of 0.11 lg ml À1 in vitro without cytotoxicity against MRC-5 cells (IC 50 ¼27.8 lg ml À1 ).

Raman microspectroscopy is a minimally invasive technique that can identify molecular structure without labeling. In this study, we demonstrate in vivo detection of the bioactive compound penicillin G inside Penicillium chrysogenum KF425 fungus cells. Highly overlapped spectroscopic signatures acquired using Raman microspectroscopic imaging are analyzed using a multivariate curve resolution-alternating least squares (MCR-ALS) method to extract the pure