Direct spectroscopic (FTIR) detection of intraspecific binary contaminations in yeast cultures

Abstract

Fourier transform infrared spectroscopy has proved to be a good method to identify and characterize microorganisms. This technique has been proposed as a tool to determine the level of contamination in binary mixtures of strains belonging to different species and even to diverse kingdoms, showing a good linear relationship between spectral outputs and contamination levels. The monitoring of intraspecific contamination is a critical point in both laboratory practice and industrial monitoring, but it is challenged by the difficulty to discriminate between very similar cultures belonging to the same species. In this paper we considered binary intraspecific mixtures of strains belonging to three species (Saccharomyces cerevisiae, Debaryomyces hansenii and Rhodotorula minuta). Results showed that contaminated and pure cultures can be discriminated on the basis of their infrared spectra and that different spectral areas respond to the contamination according to the species under test. Moreover, some spectral areas change linearly with the increase of contaminants, giving the possibility of using this procedure for preliminary estimations of the contamination in addition to the even more important opportunity to indicate the presence of contaminants of the same species at low levels in fermentation cultures.

A systems-level approach for metabolic engineering of yeast cell factories

“…The first is interested in looking at all metabolites simultaneously, identifying and quantifying specific compounds, and clustering them into specific categories or conditions. For that, multivariate analysis such as cluster analysis, principal component analysis or partial least-squares are commonly used (Allen et al, 2003;Henschke et al, 2006;Rellini et al, 2009). In targeted profiling, metabolite identification and quantification is achieved by comparing the spectrum of interest to a library of reference spectra of pure compounds.…”

Carbon availability affects already large species-specific differences in chemical composition of ectomycorrhizal fungal mycelia in pure culture

“…Studies are published on changes in chemical composition during hyphal growth and morphogenesis (Adt et al 2006 ; Jilkine et al 2007 ; Szeghalmi et al 2007 ), detection of fungi in different plant substrates (Kos et al 2002 ; Naumann et al 2005 ), differentiation of plant pathogen isolates, molds, and fungi in food industry (Lecellier et al 2015 ; Pomerantza et al 2014 ; Salman et al 2012 ; Shapaval et al 2010 ), and processes involving fungi such as substance transformations, decomposition, and carbon sequestration (Jeewani et al 2021 ; Mrnka et al 2020 ). The method has also been suggested to distinguish between fungal species (Adt et al 2006 ; Essendoubi et al 2005 ; Fischer et al 2006 ; Lecellier et al 2015 ; Naumann et al 2005 ; Rellini et al 2009 ; Santos et al 2010 ). Most studies of species’ differences have used fungal isolates grown under controlled growth conditions (e.g., Lecellier et al 2014 ; Naumann et al 2005 ) to avoid alterations of spectra due to fungal responses to environmental changes (Pena et al 2014 ).…”

Carbon Availability Affects Already Large Species-Specific Differences in Chemical Composition of Ectomycorrhizal Fungal Mycelia in Pure Culture

“…Studies are published on changes in chemical composition during hyphal growth and morphogenesis (Adt et al 2006;Jilkine et al 2007;Szeghalmi et al 2007), detection of fungi in different plant substrates (Kos et al 2002;Naumann et al 2005), differentiation of plant pathogen isolates, molds, and fungi in food industry (Lecellier et al 2015;Pomerantza et al 2014;Salman et al 2012;Shapaval et al 2010), and processes involving fungi such as substance transformations, decomposition, and carbon sequestration (Jeewani et al 2021;Mrnka et al 2020). The method has also been suggested to distinguish between fungal species (Adt et al 2006;Essendoubi et al 2005;Fischer et al 2006;Lecellier et al 2015;Naumann et al 2005;Rellini et al 2009;Santos et al 2010). Most studies of species' differences have used fungal isolates grown under controlled growth conditions (e.g., Lecellier et al 2014;Naumann et al 2005) to avoid alterations of spectra due to fungal responses to environmental changes (Pena et al 2014).…”