– Relative abundance of main Classes observed in fresh samples:frozen at -20 ºC; -80 ºC; guanidine at 4 ºC and guanidine at room temperature.

	Fresh %	-20 ºC %	-80 ºC %	Guanidine 4 ºC %	Guanidine room temperature %	p value	pc
Clostridia	47.66	54.65	51.18	43.01	44.58	0.512
Bacteroidia	42.79	36.17	39.76	47.32	44.16	0.630
Erysipelotrichi	2.53	3.26	3.05	2.01	1.91	0.337
Betaproteobacteria	1.64	0.81	0.91	2.81	2.83	0.004	0.044
Fusobacteriia	1.61	0.39	0.52	1.14	1.65	0.975
Gammaproteobacteria	0.71	0.88	0.75	0.36	0.53	0.893
Bacilli	0.64	0.86	0.71	0.59	0.57	0.789
Mollicutes	0.35	0.37	0.33	0.41	0.33	0.970
Deltaproteobacteria	0.28	0.33	0.43	0.38	0.63	0.687
Alphaproteobacteria	0.20	0.15	0.12	0.28	0.35	0.837
Lentisphaeria	0.12	0.01	0.01	0.33	0.38	0.116
Outros	1.47	2.12	2.23	1.36	2.08

p: p value obtained from Kruskal Wallis test; pc: p value corrected by Bonferroni for multiple tests.