TABLE 2.

Effect of the residual P(3HB) formed during first-step cultivation of H. pseudoflava in Luria-Bertani medium for 22 h on the composition of polyesters that accumulated during second-step cultivation in which the strain was grown on γ-butyrolactone (2.2 g/liter) as the sole carbon source for 48 h^a

First-step cultivation				Second-step cultivation with γ-butyrolactone
Addition to medium	Dry cell wt (g/liter)	P(3HB) content (%, wt/wt)	Concn of residual P(3HB) (g/liter)b	Dry cell wt (g/liter)	Polyester content (%, wt/wt)	Polyester composition (mol%)b		Concn of residual 3HB in the polymer (g/liter)	% γ-Butyrolactone
						3HB	4HB		Used for 4HBc	Unused
Noned	1.61 ± 0.02	3.23 ± 0.12	0.052 ± 0.003	2.40 ± 0.02	30.4 ± 0.1	11 ± 1	89 ± 1	0.083 ± 0.004	29 ± 2	13 ± 1
NaCl (170 mM)e	1.87 ± 0.02	11.1 ± 0.20	0.206 ± 0.003	2.25 ± 0.04	33.3 ± 0.8	9 ± 1	91 ± 1	0.067 ± 0.007	31 ± 2	11 ± 1
KCl (170 mM)e	1.73 ± 0.02	3.51 ± 0.08	0.061 ± 0.001	2.20 ± 0.08	30.6 ± 0.6	5 ± 1	95 ± 1	0.045 ± 0.006	29 ± 2	11 ± 1

^aCells grown in Luria-Bertani medium were transferred to PHA synthesis mineral medium containing γ-butyrolactone (2.2 g/liter) and 0.6 g of ammonium sulfate per liter for polyester accumulation. 

^bCalculated from gas chromatographic data. 

^cPercent conversion of γ-butyrolactone (2.2 g/liter) to 4HB in the polymer. 

^dAll values are averages for three different experiments. 

^eAll values are averages for six different experiments.