In the course of screening of antibiotics, a new antibiotic was obtained from the cells of a bacterium which was isolated from a soil sample collected in Chiba Prefecture, Japan.

The cultural characteristic of the bacterium was investigated by the authors¹⁾. The antibiotic was named pyrrolnitrin and isolated as pale yellow crystals. Pyrrolnitrin has a growth inhibitory effect against fungi, yeasts and Gram-positive bacteria, and has low toxicity.

This paper deals with fermentation, isolation and properties of pyrrolnitrin.

In the previous paper¹⁾, it was reported that bacterium No. 2327 strain produced a new antibiotic, pyrrolnitrin.

The present paper deals with the taxonomic studies on the No. 2327 strain.

Pyrrolnitrin (hereinafter referred to as PN) is a new antifungal antibiotic, recently isolated from Pseudomonas pyrrocinia n. sp. by Arima et al¹⁾., and the chemical structure of this substance is established as follows : ¹⁾

The above chemical structure was confirmed synthetically by this laboratories²⁾.

Comprehensive studies of PN were undertaken to observe its antimicrobial activity in vitro, its distribution in the body and excretion after oral administration, its therapeutic activity on animals with experimentally-induced fungal infection and its toxicity.

The antifungal activities of PN were compared with those of other widely used antifungal agents.

Neocarzinostatin is a new antibiotic isolated from culture filtrate of Streptomyces carzinostaticus F-41¹⁾. The antibiotic exerts a striking inhibitory effect on growth of some experimental tumors¹⁾ and various studies have been made in this laboratory to elucidate the mode of action of neocarzinostatin^2,3). The present report concerns with the cytological changes of sarcoma 180 tumor cells produced by neocarzinostatin in vivo.

Fusidic¹⁾ and helvolinic²⁾ acids are produced by fungi and belong to the group of steroidal antibiotics of protolanostane skeleton, together with helvolic acid³⁾ and cephalosporin P₁⁴⁾. Helvolinic acid is also obtained by partial hydrolysis of helvolic acid. They exhibit an antibacterial activity against Gram-positive organisms, including penicillinresistant Staphylococci.

The morphological changes in bacteria induced by antibiotics and chemotherapeutic agents have been reported in the literatures^(1~5).

Since elongation of E. coli cells was noticed under the influence of anticancer agents, we studied this respect in details and divided chemotherapeutic agents and antibiotics into 3 groups and 6 types according to the morphological changes in E.coli B cells treated with these substances⁶⁾. Most of anticancer agents are grouped into the 1 st group (elongation group); most of antibacterial and antifungal agents into the 2nd group (agglomeration group); and some anticancer and antibacterial agents into the 3rd group (apparently no morphological change). The followings are the detailed description of the morphological changes in the cells of E.coli B and other Gram-positive and Gram-negative bacteria induced by several representative substances belonging to the respective group.