Evaluation of growth characteristics of Aspergillus parasiticus inoculated in different culture media by shortwave infrared (SWIR) hyperspectral imaging

Authors: CHU, XUAN - China Agricultural University; WANG, WEI - China Agricultural University; Ni, Xinzhi; ZHENG, HAITAO - China Agricultural University; ZHAO, XIN - China Agricultural University; Zhuang, Hong; Lawrence, Kurt; LI, CHUNYANG - Jiangxi Academy Of Agricultural Sciences; LI, YUFENG - Chinese Academy Of Sciences; LU, CHENGJUN - Chinese Academy Of Sciences

Submitted to: Journal of Innovative Optical Health Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2018
Publication Date: 9/12/2019
Citation: Chu, X., Wang, W., Ni, X., Zheng, H., Zhao, X., Zhuang, H., Lawrence, K.C., Li, C., Li, Y., Lu, C. 2019. Evaluation of growth characteristics of Aspergillus parasiticus inoculated in different culture media by shortwave infrared (SWIR) hyperspectral imaging. Journal of Innovative Optical Health Sciences. 11(5):Article 1850031 (15 pages).

Interpretive Summary: Toxin-producing fungus and pathogenic microbial contaminations in crop production and food processing has long been one of the critical impediments in human food and animal feed industries in general. In the past decades, hyperspectral imaging has been successfully applied for modeling growth of several varieties of fungi. Recently, hyperspectral image technique has become increasingly important for rapid and nondestructive testing for the quality and safety assessment of food and agricultural products. This study was aimed at observing the growth characteristics of a fungus incubated on two different nutritional media using shortwave infrared hyperspectral imaging technique. The specific objectives were to (1) examine growth phases and growth zones of the fungal colonies incubated on each of the two media for different durations, and determine their specific spectral signature; (2) acquire feature parameters and select characteristic wavelengths to identify and discriminate the fungus incubated on different media; and (3) classify varying growth zones in the fungal colonies incubated on different media using classification models based on the spectra of selected characteristic wavelengths. The research has demonstrated that hyperspectral imaging technology is a powerful tool for evaluation of fungal growth characteristics incubated in different culture media.

Technical Abstract: The growth characteristics of Aspergillus parasiticus incubated on two culture media were examined using shortwave infrared (SWIR, 1000–2500 nm) hyperspectral imaging (HSI) in this work. HSI images of the A. parasiticus colonies growing on rose bengal medium (RBM) and maize agar medium (MAM) were recorded daily for 6 d. The growth phases of A. parasiticus were indicated through the pixel number and average spectra of colonies. On score plot of the first and the second principal components (i.e., PC1 and PC2), four growth zones with varying mycelium densities were identified. Eight characteristic wavelengths (1095, 1145, 1195, 1279, 1442, 1655, 1834 and 1929 nm) were selected from PC1 loading, average spectra of each colony and each growth zone. Furthermore, support vector machine (SVM) classifier based on the eight wavelengths was built, and the classification accuracy for the four zones (from outer to inner zones) on the colonies on RBM were 99.77%, 99.35%, 99.75% and 99.60% and 99.77%, 99.39%, 99.31% and 98.22% for colonies on MAM. In addition, a new score plot of PC2 and PC3 was used to differentiate the colonies incubated on RBM and MAM for 6 d. Then characteristic wavelengths of 1067, 1195, 1279, 1369, 1459, 1694, 1834 and 1929 nm were selected from the loading of PC2 and PC3. Based on these characteristic wavelengths, a new SVM model was developed to differentiate colonies on RBM and MAM with accuracy of 100.00% and 99.99%, respectively. In conclusion, SWIR hyperspectral image is a powerful tool for evaluation of growth characteristics of A. parasiticus incubated in different culture media.