Table 3.

Bacterial headspace compounds.

Compounds found in lower amounts in diluted samples and control	RT (min)	R2 (%)	P-value	Exponential regression parameters A + B*(R**X)			Studies on human odour
				A	B	R
1-butanol1	4.89	83.2	< 0.001	2.21*107	-1.79*107	3.09*10-16	[16,41]
2,3-butanedione1	3.42	78.1	0.002	2.34*107	-1.99*107	3.77*10-246
2-hydroxy-3-pentanone	8.49	94.1	< 0.001	1.39*106	-1.02*106	8.54*10-26
2-methyl-1-butanol1	6.70	97.1	< 0.001	-4.93*106	5.05*106	2.89*104	[16]
2-methylbutanal1	4.97	98.7	< 0.001	1.11*107	-1.04*107	1.32*10-13	[15,39]
2-methylbutanoic acid1	9.30	96.8	< 0.001	1.52*106	-1.41*106	8.56*10-22	[16]
3-hydroxy-2-butanone1	5.99	95.0	< 0.001	8.51*107	-8.24*107	2.31*10-34	[16]
3-methyl-1-butanol1	6.61	97.0	< 0.001	-5.12*107	5.22*107	4.25*103	[16]
3-methylbutanal1	4.75	98.1	< 0.001	2.74*107	-2.51*107	7.89*10-15	[39]
3-methylbutanoic acid1	9.07	92.9	< 0.001	5.42*106	-4.69*106	6.63*10-28	[16,41]
benzeneethanol1	15.70	86.0	< 0.001	1.14*107	-7.12*106	1.01*10-23
unknown 1	16.48	94.7	< 0.001	6.28*105	-6.12*105	5.72*10-18
unknown 2	20.22	96.5	< 0.001	7.41*105	-7.04*105	5.50*10-14
unknown 3	23.51	94.1	< 0.001	1.93*106	-1.96*106	4.80*10-48
Compounds found in higher amounts in diluted samples and control
furfural	9.18	82.8	< 0.001	1.03*106	1.34*107	1.49*10-30

Compounds detected in the headspace of the skin microbiota samples, but not present or in significantly higher or lower amounts in the diluted samples and control (exponential regression, P < 0.01). Increase in the abundance of compounds is explained by the parameters in the exponential regression model (A + B*(R**X); X = concentration of bacteria). Numbers in last column refer to studies in which compounds were reported previously. All compounds were identified on the basis of matching spectra (NIST library), and verified by injection of standard (except 2-hydroxy-3-pentanone). ¹Compounds tested in MM-X traps. RT = retention time. R² = coefficient of determination.