As reported in a previous paper¹⁾, two antifungal substances were isolated from a culture filtrate of S. fungicidicus. The one, unamycin, was a tetraene antifungal substance and another, unamycin B, was an antifungal substance related to toyokamycin²⁾ and the antibiotic E-212³⁾. Processes for production and isolation and properties of these antifungal substances were described in the previous paper. Antifungal effects, and toxicities are presented in this paper.

In the course of searching new antibiotics using Mycobacterium tuberculosis BCG as the test organism, two antitubercular antibiotics were obtained as crystalline forms from the culture fluid of a streptomyces which was isolated from the soil collected in Kunitachi, Tokyo and their chemical and physical properties, biolgical activities and chemical structures were studied. They were identified as 6-aminophenoxazone and o-aminophenol respectively. Altough these compounds have been already synthesized and known to have antitubercular activities¹⁾, they were firstly isolated from culture fluid of a streptomyces by authors and the former was named questiomycin A and the latter questiomycin B respectively. In this paper the authors wish to describe the isolation, purification, chemical and physical properties, microbiological spectra and the structural determinations of these two antibiotics.

In the course of searching new antibiotics using Mycobacterium tuberculosis BCG as the test organism, the authors obtained a crystalline antibiotic from the culture fluid of a streptomyces isolated from the soil of Urawa city, Saitama Prefecture. It was named bovinocidin. This antibiotic was found to have a weak activity only against Mycobacterium tuberculosis BCG and no activity was observed against other microorganisms including Mycobacterium tuberculosis H₃₇Rv. In the course of the further studies, this antibiotic was found to be β-nitropropionic acid. As the natural metabolites, this compound was first obtained as hiptagenic acid^1,2) by Gorter from the degradation products of hiptagin, a glycoside of the root bark of Hiptage madablota. Next Buch et al.³⁾ isolated this compound as “a toxic fraction of very low antibiotic activity” from the flavicin-producing fungus named Aspergillus flavus. Nakamura et al.⁴⁾ is also isolated the same compound from the culture fluid of Aspergillus oryzae and described its activity against “Hiochi” bacteria. But as the metabolite of streptomyces, β-nitropropionic acid was firstly obtained by authors. In this report the isolation and purification, the antimicrobial activities and the structural determination were described.

The antibiotic mikamycin was isolated from a broth culture of Streptomyces mitakaensis by Arai et al.^1,2) of the Institute of Applied Microbiology, University of Tokyo, in 1956. Thereafter, another antibiotic was found in the same broth culture and the previous one was named mikamycin A and the other mikamycin B^3,4). As described by Tanaka et al.^5,6), these antibiotics inhibit mainly the growth of grampositive bacteria both in vitro and in vivo and show no cross-resistance with those antibiotics which have been in medical and veterinary use up to date. Mikamycins A and B show a high synergistic action which becomes most significant when 30 to 90% mikamycin A is contained in the mixture of mikamycin A and mikamycin B. Tanaka et al.⁶⁾ reported that S. aureus, when treated with B, raised its sensitivity to A.

With mikamycins supplied by the Institute of Applied Microbiology, the authors studied absorption and excretion of the antibiotics in dogs and their toxicity to dogs in case of long-term oral administration. This paper deals with these studies.

Among antiviral antibiotics from Streptomyces, ehrlichin¹⁾, cardicin²⁾, abikoviromycin³⁾, achromoviromycin⁵⁾ and myxoviromycin⁶⁾, only achromoviromycin was described to be effective against Japanese B encephalitis virus. As a chemical agent, PANS⁷⁾ was clinically applied to Japanese B encephalitis. Yet, no substance possesses a complete suppressive effect on Japanese encephalitis clinically.

In our laboratory, soil-isolates of streptomyces had been examined for their activities against Japanese B encephalitis virus along with their activities against bacteria, cancers and others. As a result, culture broth of a strain of streptomyces, No. Z-1120, was found to contain a substance, active against Japanese encephalitis virus in vitro as well as in vivo. This strain was isolated from a soil sample obtained at Honmonji temple, Ikegami, Ohta-ku, Tokyo. Since the active principle was extracted from the culture broth and has been proved to be a new substance, it was given the name of cephalomycin by Hata and others⁸⁾. The present paper deals with mycological studies on the strain No. Z-1120, a source of cephalomycin, fermentation and extraction processes and chemical, physical and biological properties of cephalomycin.