Increasing cell biomass in Saccharomyces cerevisiae increases recombinant protein yield: the use of a respiratory strain as a microbial cell factory

Table 2 Recombinant Fps1 yields per unit of total membrane protein are identical for two wild-type S. cerevisiae strains and respiratory TM6*

	Fps1 yield expressed as a mean densitometry signal
Strains	All samples	Glucose phase	Ethanol phase	Stationary phase
954 VW K70	3.3 (0.3; n = 2)	3.2 (0.1; n = 2)	3.5 (0.9; n = 2)	2.6 (0.8; n = 2)
KOY.PK2-1C82	3.7 (0.6; n = 3)	3.7 (0.6; n = 3)	3.7 (0.9; n = 3)	2.5 (0.9; n = 3)
TM6*	3.1 (0.7; n = 3)	3.2 (0.8; n = 3)	-	2.4 (0.9; n = 3)

Immunoblots were performed and quantified on membrane-bound fractions from two wild-type cultures and the TM6* strain, producing recombinant Fps1. The values given are mean densitometry signals related to our internal standard as described in the Methods section. Standard error of the mean, in parentheses, was calculated for replicate cultures as indicated. Note that there is no significant yield improvement per unit of total membrane protein for production in TM6* compared with these wild-types: increased yield is achieved on account of improved biomass production in TM6* (see Figure 2). Note also that since TM6* does not have an ethanol phase (-), the "stationary phase" samples were harvested at least 10 h after glucose exhaustion.

ISSN: 1475-2859