Primary biodegradation of amine oxide and quaternary ammonium amphiphiles.

Biodegradation of two amphiphilic "soft" antimicrobially active derivatives of lauric (dodecanoic) acid, a quaternary ammonium salt and an amine oxide bearing an amide or ester group, was followed using microorganisms from activated sludge. Primary biodegradation was determined by ion-selective electrodes, total biodegradation as the chemical oxygen demand. Though organic ammonium salts quickly undergo primary biodegradation, the rest of the molecule is difficult to destroy. In contrast, amine oxides are easily biodegradable.

Enhanced biodegradation of a hard bis-quaternary ammonium salt.

Bacterial strains with a high biodegradation potential were isolated from activated sludge. Their ability to decompose the hard bis-quaternary ammonium salt FB was determined by the method of chemical oxygen demand (COD) in a mineral medium, where the compound FB was the only source of carbon. The COD values were very low after 21 d and in the course of this period they reached zero level twice. The contribution of adsorption to decrease the COD value was small. The maximum COD decrease was accompanied by an increase of cell respiration. It is suggested that FB is effectively decomposed in spite of the fact that according to its structure it is a typical hard detergent.

Adsorption on bacterial spores depending on the aggregation properties of antimicrobial tensides.

A change in interaction with spores of Bacillus cereus occurred in the range of critical concentrations of micelle formation. With 1-methyldodecyldimethylamine-N-oxide and N,N'-bis(dodecyldimethyl)-1,2-ethanediammonium dibromide, the induced release of dipicolinic acid was blocked and the adsorption dynamics changed, respectively.

Antibacterial activity of new synthesized amino-oxides and quaternary ammonium salts.

An amino oxide and three quaternary ammonium salts were investigated for antimicrobial activity. All compounds had low MIC against gram positive bacteria. Despite high MIC the ammonium salts gave good killing of Pseudomonas aeruginosa in time kill experiments. These quaternary ammonium salts may be useful for disinfection as they are easily broken down in the environment.

Inhibitory effect of 1-methyldodecyldimethylamine oxide and N,N-bis(dodecyldimethyl)-1,2-ethanediammonium dibromide on the spores of Bacillus cereus.

1-Methyldodecyldimethylamine oxide (MDDO) and N,N'-bis(dodecyldimethyl)-1,2-ethanediammonium dibromide (BDED) exhibit a significant affinity for the surface of Bacillus cereus spores and adsorb very rapidly to the cells; they have a pronounced inhibitory effect on spore outgrowth. In order to alter the affinity of the spore surface for these inhibitors, the spores were pretreated with sodium dodecyl sulfate (SDS), and with an electronegative (Tween 80) and electropositive (histone) compound. In SDS-pretreated spores the inhibitory effect of MDDO and BDED was abolished to a considerable extent. Whereas the development of intact spores was inhibited already after germination, in SDS-pretreated spores the postgermination development continued but was not completed. In Tween 80-pretreated spores the addition of BDED led only to a retardation of outgrowth and division; BDED added only during the division stage interrupted further development completely. Histone-pretreated spores stopped their development instantaneously after the addition of BDED at any phase of the postgermination development. The possible mechanisms of the interaction of the compounds used with spore surface or rather with the state of its structures are discussed.

Antimicrobial activity of some salts of dialkylthiophosphoric acids.

A total of 18 derivatives of O,O-dialkylthio- and O,O-dialkylthiophosphoric acids were tested for antimicrobial activity using strains of Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Candida albicans. The activity was found to depend on the length of the alkyl substituent and/or the cation size. All derivatives were ineffective with E. coli and C. albicans.

The effect of quaternary ammonium compounds and amine oxides on spores of Bacillus cereus.

The effect of 1-dodecylpiperidine 1-oxide and N,N'-bis(dodecyldimethyl)-1,2-ethane diammonium dibromide on the spores of Bacillus cereus. particularly their binding to intact spores and spores with reduced cystine bonds, was investigated. The Langmuir type of binding is involved in both cases. Both compounds decreased the thermoresistance of spores. DPNO decreased the fraction of non-germinating spores, the effect of the drug increasing with increasing concentration. This phenomenon was associated with a faster release of dipicolinic acid to the medium. Only microgermination proceeded in the presence of BDED and dipicolinic acid was released only in substantially lower amounts. Both compounds also influenced respiration.