Examination of physiological and molecular factors involved in enhanced solvent production by clostridium beijerinckii BA101

Abstract

The specific activities and the mRNA expression levels associated with coenzyme A transferase, acetoacetate decarboxylase, and butyraldehyde dehydrogenase were elevated in hyper-solvent-producing Clostridium beijerinckii BA101 during the exponential growth phase. The increase in expression of the sol operon and associated enzyme activities may be responsible for enhanced solvent production by C. beijerinckii BA101.

FIG. 1

Specific activities of solventogenic and acidogenic enzymes of C. beijerinckii NCIMB 8052 and BA101 following growth in 1 liter of semidefined P2 medium containing 6% glucose. (A) CoAT (acetoacetyl CoA:acetate-butyrate CoAT). (B) AADC. (C) BADH (NAD⁺ dependent). (D) BDH (NAD⁺ dependent). (E) PTA. (F) AK. (G) PTB. (H) BK. Symbols: □, NCIMB 8052; ■, BA101. The samples were collected from fermentations. Data are averages of data from duplicate experiments in which each sample was assayed three times; the standard deviations were within 7%.

FIG. 2

Northern hybridization analysis of RNA isolated at various times from C. beijerinckii NCIMB 8052 and BA101 following growth in 1 liter of semidefined P2 medium containing 6% glucose and probed with the ctfAB probe (A) or the ptb probe (B). The upper portion of each panel is the X-ray film picture of a Northern blot, and the lower portion of each panel is a densitometric analysis of the X-ray film. The relative intensities of transcripts are presented as percentages of the maximum transcript intensity, and the sample with the highest density was considered the sample with the maximum intensity. The arrows indicate the sizes of the transcripts.