Detection of bacterial contamination in cultures of eucaryotic cells by gas chromatography–mass spectrometry

Abstract

The use of gas chromatography-mass spectrometry for early detection of bacterial contaminations in cultures of baker's yeast, Penicillium chrysogenum, and an animal cell line was evaluated; muramic acid and characteristic cellular fatty acids were used as analytes. By analyzing branched-chain and cyclopropane-substituted fatty acids as methyl esters, Staphylococcus epidermidis, Bacillus subtilis, Lactobacillus reuteri, Enterobacter cloacae, and Pseudomonas fluorescens were detected in a 500-fold excess (w/w) of baker's yeast; the amounts injected corresponded to 300 ng (dry mass) of the bacteria. Contamination with Bacillus was detected in cultures of Penicillium chrysogenum and animal cells by analyzing muramic acid, both as its alditol acetate derivative, using electron impact ionization, and its trifluoroacetyl methyl glycoside derivative, using negative ion-chemical ionization. The trifluoroacetylated derivative was detected in injected amounts corresponding to 1 x 10(3) bacterial cells in the contaminated animal cell line, whereas amounts corresponding to 1 x 10(5) bacteria were required for detection of the alditol acetate derivative; the amounts in the original samples were 5 x 10(5) and 5 x 10(6), respectively. However, the alditol acetate method exhibited lower chemical interferences than the trifluoroacetyl methyl glycoside procedure. The results show the potential of using gas chromatographic-mass spectrometric analysis of cellular constituents for the detection of bacterial contaminations in eucaryotic cultures as an alternative to conventional microbiological methods.

An Exometabolomics Approach to Monitoring Microbial Contamination in Microalgal Fermentation Processes by Using Metabolic Footprint Analysis

“…The targeted analysis of signature metabolites is an approach that has been used in many studies for the detection of microorganisms in complex samples (4)(5)(6)16). Certain metabolites have been considered indicative of the presence of particular microorganisms.…”

“…Certain metabolites have been considered indicative of the presence of particular microorganisms. These include muramic acid for all bacteria, myristic acid for Gram-negative bacteria, and glucosamine for fungi (4)(5)(6). However, these metabolic markers are not completely specific for a group of microorganisms, and it is known that the quantities of these metabolites vary from species to species, making it difficult to ascertain consistently the level of contamination based on metabolite levels.…”

“…Very few studies have examined the entire metabolite profile of contaminated cultures. Elmroth et al (5,6) previously compared the metabolite profiles of axenic cultures against those of contaminated cultures. Those authors detected changes in the metabolite profiles caused by the presence of microbial contaminants.…”

Online prediction for contamination of chlortetracycline fermentation based on Dezert–Smarandache theory

“…These are broadly classified into physical and biological methods. The use of physical methods such as light, radiometry, and chromatography facilitates the rapid, precise, and non-invasive evaluation of broth [2][3][4]. However, their disadvantages lie in the cost of equipment, which are very expensive and require a high level of maintenance, and the tests are timeconsuming and do not allow online application.…”