Identification of Lactic Acid Bacteria and Propionic Acid Bacteria using FTIR Spectroscopy and Artificial Neural Networks

Bartlłomiej Dziuba* and Beata Nalepa

University of Warmia and Mazury in Olsztyn, Faculty of Food Science,

Department of Industrial and Food Microbiology, Plac Cieszyñski 1, PL-10-957 Olsztyn, Poland

Article history:

Received June 27, 2011
Accepted February 3, 2012


lactic acid bacteria, propionic acid bacteria, FTIR spectroscopy, artificial neural networks


In the present study, lactic acid bacteria and propionic acid bacteria have been identified at the genus level with the use of artificial neural networks (ANNs) and Fourier transform infrared spectroscopy (FTIR). Bacterial strains of the genera Lactobacillus, Lactococcus, Leuconostoc, Streptococcus and Propionibacterium were analyzed since they deliver health benefits and are routinely used in the food processing industry. The correctness of bacterial identification by ANNs and FTIR was evaluated at two stages. At first stage, ANNs were tested based on the spectra of 66 reference bacterial strains. At second stage, the evaluation involved 286 spectra of bacterial strains isolated from food products, deposited in our laboratory collection, and identified by genus-specific PCR. ANNs were developed based on the spectra and their first derivatives. The most satisfactory results were reported for the probabilistic neural network, which was built using a combination of W5W4W3 spectral ranges. This network correctly identified the genus of 95 % of the lactic acid bacteria and propionic acid bacteria strains analyzed.

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