Table 2.

Top 30 extracellular proteins in C. acetobutylicum biofilm identified by LC–MS/MS

	Gene locus	Scorea	Massb	Matchesc	Sequencesd	emPAIe	Description
1	CA_C2703	10,961	58,166	408	29	12.3	Molecular chaperone GroEL (Hsp60)
2	CEA_G3563	3556	47,277	139	17	10.3	Putative S-layer protein
3	CA_C3597	8141	20,493	187	10	10.3	Rubrerythrin
4	CA_C2710	2299	28,089	71	14	9.5	Electron transfer flavoprotein beta-subunit
5	CA_C0709	1619	35,999	72	15	8.1	Glyceraldehyde-3-phosphate dehydrogenase
6	CA_C2452	572	15,611	24	7	7.7	Flavodoxin
7	CA_C1555	2446	29,503	80	10	7.5	Flagellin
8	CA_C1747	556	8602	21	3	6.9	Acyl carrier protein, ACP
9	CA_C3136	5404	43,482	207	18	6.8	Elongation Factor Tu (Ef-Tu)
10	CA_C2990	396	7307	23	2	6.2	Cold shock protein
11	CA_C1834	448	9203	19	4	5.9	Host factor I protein Hfq
12	CA_C3125	299	7908	7	3	5.4	Ribosomal protein L29
13	CA_C2712	571	28,400	28	10	4.9	Crotonase
14	CA_C1807	182	10,251	7	5	4.8	Ribosomal Protein S15
15	CA_C3211	1113	10,341	59	6	4.7	DNA binding protein HU
16	CA_P0164	1098	23,666	33	8	4.6	Acetoacetyl-CoA:acetate/butyrate CoA-transferase subunit B
17	CA_C2704	745	10,420	27	5	4.6	Molecular chaperone groES (Hsp10, Hsp60 cofactor)
18	CA_C3145	553	12,670	24	5	4.4	Ribosomal protein L7/L12
19	CA_C3076	627	32,321	30	12	4.3	Phosphate butyryltransferase
20	CA_C1281	757	17,734	29	7	3.8	Heat shock protein grpE (hsp20, Hsp70 cofactor)
21	CA_C1282	2280	65,723	77	24	3.8	Molecular chaperone DnaK (Hsp70)
22	CA_C2229	4951	129,740	191	43	3.7	Pyruvate:ferredoxin oxidoreductase
23	CA_C2641	782	49,565	37	19	3.7	FKBP-type peptidyl-prolyl cis-transisomerase (trigger factor)
24	CA_C3075	744	39,146	33	15	3.7	Butyrate kinase, BUK
25	CA_C2873	1247	41,443	53	16	3.7	Acetyl coenzyme A acetyltransferase (thiolase)
26	CA_P0165	725	23,797	22	8	3.3	Acetoacetate decarboxylase
27	CA_P0162	3768	95,774	175	32	3.2	Alcohol dehydrogenase E
28	CA_C0711	452	26,698	17	11	3.1	Triosephosphate isomerase
29	CA_C2597	461	17,599	19	5	3.1	Hypothetical protein
30	CA_C3558	1128	48,599	51	10	3.0	Probable S-layer protein

^aAll scores were statistically significant (p < 0.05; Student t test). Higher score means higher probability

^bTheoretical molecular mass

^cThe number of peptides that matched the identified protein with p < 0.05

^dThe number of distinct (nonredundant) peptides that matched the identified protein with p < 0.05 (Student t test)

^eExponentially modified Protein Abundance Index