Several species of the genus Pleurotus have been found in this laboratory to form substances inhibitory for Staphylococcus aureus. Among these were two species, Pleurotus mutilus (Fr.) Sacc. and P. Passeckerianus Pilat, obtained from the Centraalbureau voor Schimmelcultures at Baarn. An antibacterial substance formed by these fungi was isolated in crystalline form from culture liquids; it was named pleuromutilin. P. mutilus grown on corn-steep, thiamine-peptone, or potato-dextrose agars for two days and tested by the streak-method, markedly inhibited Staphylococcus aureus, inhibited incompletely Mycobacterium smegma, and had no effect on Escherichia coli. Agar disks cut from colonies 10 days old formed inhibition zones 20 mm. in diameter with S. aureus and a small zone of incomplete inhibition with M. smegma. P. Passeckerianus produced similar zones of inhibition. Still Cultures.-P. mutilus was grown at 25°C. in 2800 ml. Fernbach flasks containing beech-wood shavings and a corn-steep medium.' About four weeks after inoculation the mycelium covered the surface of the liquid and the activity against S. aureus was about 512 dilution units per ml. Reflooding the mats with fresh corn steep medium resulted in as high activity in about one week after reflooding. The reflooding was repeated at about 10-day intervals until the mat became so thick that the operation was difficult. The flasks inoculated with P. Passeckerianus reached an activity of 256 dilution units per ml. in about one month.
BOTANY: ANCHEL, HERVEY AND ROBBINS PROC. N. A. S. 7. Certain combinations of neomycin and streptomycin showed considerably greater bacteriostatic and bactericidal effects than the corresponding concentrations of either antibiotic alone or concentrations of streptomycin equal to the total number of units of both antibiotics. Such antibacterial effects were never greater, however, than concentrations of neomycin equal to the total units of the two antibiotics. Very small amounts of neomycin in synergistic mixtures with streptomycin had a much greater effect than streptomycin alone. 8. No marked increase in the resistance of E. coli cells which survived exposure to neomycin and streptomycin was observed toward eitfier antibiotic or combinations of the two. 9. The neomycin-resistant strain of E. coli showed some resistance to streptomycin after several weeks on media containing neither antibiotic. 10. Neomycin appears to be about four times as active, on a unit basis, as streptomycin against many bacteria. In view of the fact that the most potent neomycin preparations so far obtained have 250 units per milligram, the antibacterial potency of the two antibiotics is about similar on a gram basis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.