Table 2.

Applications of FT-IR in microbial identification.

Research goal	Microorganism	Data analysis	Reference
Compare the macrosample and microsample methods to evaluate which approach is more suited to the identification of Listeria spp. based on FT-IR spectra.	Listeria spp.	Leave-one-out method	Rebuffo-Scheer et al. (2008)
Determine the suitability of FT-IR as a supplement to MALDI-TOF MS for the identification and typing and identification microorganisms	Escherichia coli and Shigella species.	Correlation analysis, Principal component analysis (PCA), and hierarchical clustering analysis (HCA).	Feng et al. (2020)
Develop and validate an FTIR-ATR method for rapid identification of contaminants in pharmaceutical products	Bacillus subtilis, Candida albicans, Enterococcus faecium, Escherichia coli, Micrococcus luteus, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus, and Staphylococcus epidermidis.	PCA and linear discriminant analysis (LDA).	Brito and Lourenço (2021)
Evaluate the potential of FT-IR for rapid identification of Bacillus isolates	Bacillus cereus, Bacillus mycoides, Bacillus thuringiensis, and other Bacillus, and non-Bacillus species.	-	Lin et al. (1998)
Differentiate and identify different lactic and propionic acid bacteria using (artificial neural networks) ANNs and FT-IR analysis; Expand the library of FTIR spectra of microorganisms	Lactobacillus, Lactococcus, Leuconostoc, Propionibacterium, Streptococcus, and Lactobacillus.	Custer analysis, Pearson’s correlation coefficient and Ward’s algorithm	Dziuba et al. (2007)
Study isolates belonging to the species Campylobacter coli and Campylobacter jejuni and to compare FT-IR typing schemes with established genomic profiles based on enterobacterial repetitive intergenic consensus PCR (ERIC-PCR)	Campylobacter coli and Campylobacter jejuni	HCA, stepwise discriminant analysis (SDA)	Lasch et al. (2004)
Use FTIR spectroscopy for the detection of the spectral parameters representing biochemical differences between species of the bacteria and fungi as well as different physiological states of the bacteria, i.e., endospores and vegetative cells of Bacillus spp.	Bacillus cereus, Bacillus atrophaeus, Bacillus megaterium, Bacillus subtilis, Escherichia coli, Micrococus luteus, Pantoea agglomerans, Alternaria alternata, Candida albicans, Cladosporium herbarum, Penicillium brevicompactum and Penicillium chrysogenum	PCA, HCA	Bombalska et al. (2011)