Effect of acetic acid on ethanol production by Zymomonas mobilis mutant strains through continuous adaptation

BMC Biotechnology

Table 1 Effect of acetate-adaptive seed culture on ZMA-142 and ZMA-167 in a 5 L fermenter using medium containing 120 g glucose/L, 195 mM sodium acetate and controlled at pH 5.0

Strains	Fermentation time (hr)	Glucose utilization (g/L)	Ethanol Production (g/L)	q _smax^a	q _Pmax^b	Yp/s ^c	Conversion Rate (%)^d
Seed culture with RM; Fermentation in FM
ZM 481	20	107.2	46.1	5.4	2.3	0.43	84.0
ZMA-142	22	99.2	46.5	4.5	2.1	0.47	91.8
ZMA-167	22	100.0	43.7	3.9	1.7	0.44	86.0
Seed culture with RM; Fermentation in FM, 195 mM NaOAc, pH 5
ZM 481	64	11.40	2.3	0.2	0.04	0.20	39.1
ZMA-142	56	103.9	48.0	1.86	0.9	0.46	90.2
ZMA-167	64	100.7	44.3	1.57	0.7	0.44	86
Seed culture with RM, 146 mM NaOAc; Fermentation in FM, 195 mM NaOAc, pH 5
ZM 481	48	12.4	2.9	0.3	0.1	0.23	45.0
ZMA-142	36	97.2	60.8	2.7	1.7	0.63	122.4
ZMA-167	48	86.6	47.4	1.8	1.0	0.55	107.2

^aqs max: Total sugar utilization rate (g l-1 h-1)
^bqp max: Ethanol production rate (g l-1 h-1)
^cYp/s: Ethanol yield on total sugars (g g-1)
^dConversion Rate(%) = (Yp/s) x 100%/(Theorical Yp/s), Theorical Yp/s = (46*2)/180.16 = 0.51143

ISSN: 1472-6750