Table 2.

Relative abundance (% of sequences) ± standard error of the five most dominant bacterial phyla in the lettuce rhizosphere grown for 55 days in the growth chamber in potting soil with and without 2% chitin after.

	Treatment
	Control	2% chitin
Proteobacteria	47.04 ± 0.18	49.79 ± 0.36*
Bacteroidetes	10.78 ± 0.12	15.54 ± 0.19*
Verrucomicrobia	10.85 ± 0.20	7.71 ± 0.25*
Acidobacteria	7.11 ± 0.13	5.37 ± 0.13*
Actinobacteria	3.87 ± 0.04	4.82 ± 0.08*
Gram negative bacteria	68.67	73.04∗
Gram positive bacteria	10.98	10.19
Total	79.65	83.24∗

Asterisk indicates a significant difference to the control (P < 0.05) by analysis of variance with n = 5. The phyla in bold have a significantly higher relative abundance in the chitin treatment as compared to the control, the underlined phyla have significantly lower relative abundance.