2.5.Principal components analysis
Prior to principal components analysis (PCA), all absorbance data were
converted into Rsi values. The ratio of the AWCD value per samples and
the maximum AWCD value in all samples is regarded the relative ratio of
six kinds of carbon sources. The ratio of the AWCD value of the sole
carbon source and the AWCD of the 31 carbon source is relative for each
carbon source, and make a comparison matrix, which could indicated that
the use regularity of strong and weak in sole carbon source.