The structure and function of Na+ channels.

The past year has seen major advances in our understanding of voltage-gated ion channels through a powerful combination of patch-clamp and molecular biological techniques. These approaches have identified regions (in some cases single amino acid residues) that are essential for voltage-dependent activation and inactivation, lining of the pore, and regulation of channel function.     

In vitro effect of ethanol on polyphosphoinositide metabolism in bulk isolated brain cells.

Metabolism of polyphosphoinositide was studied in bulk isolated brain cells. Cells were isolated by a rapid method using mechanical disruption followed by molecular seiving and centrifugation. Incorporation of [32Pi]orthophosphate into phosphatidyl inositol-4-phosphate and phosphatidylinositol-4,5 bis-phosphate was optimum at 30 and 60 min, respectively, in the isolated cells. Breakdown studies showed maximum loss of 32Pi after 60 min. Addition of ethanol at and above 10 mM concentration in vitro significantly decreased the incorporation of 32Pi into both phosphatidylinositol-4-phosphate and phosphatidylinositol-4,5 bis-phosphate by the isolated cells. However, the spontaneous breakdown of polyphosphoinositide was not altered in the presence of ethanol in vitro.     

Comparative evaluation of the metabolic potentials of different strains of Peptostreptococcus productus: utilization and transformation of aromatic compounds

Three strains of Peptostreptococcus productus were tested for growth at the expense of methoxylated aromatic compounds. Strain M8A-18 (human fecal isolate) was unable to utilize methoxylated aromatic compounds. While the type strain ATCC 27340 (human septicemia isolate) was capable of minimal growth with methoxylated aromatic compounds, ATCC 35244 (sewage sludge isolate) displayed significant growth on methoxylated aromatic compounds. Methoxylated phenols, benzoates, benzyl alcohol and phenylacrylates supported the growth of ATCC 35244 and were O-demethylated to their respective hydroxylated derivatives. During O-methyl- or CO-dependent growth, the double bond of the acrylate side chain of certain methoxylated and non-methoxylated phenylacrylates was reduced. Although other aromatic substituent groups (-COOH and -CH3) were transformed during CO-dependent growth, in short-term growth studies, the aromatic ring was not subject to reduction or degradation. Of the three strains tested, only strain M8A-18 failed to grow at the expense of carbon monoxide (CO).     

Pilot-scale production of butanol by Clostridium beijerinckii BA101 using a low-cost fermentation medium based on corn steep water

To improve the economic competitiveness of the acetone/butanol/ethanol fermentation process, glucose/corn steep water (CSW) medium was used on a pilot scale for the production of solvents. The production of butanol by the Clostridium beijerinckii NCIMB 8052 parent strain and the solvent-hyperproducing BA101 mutant was compared. In a 20-l fermentation using 5% glucose/CSW medium,  C. beijerinckii 8052 produced 8.5 g butanol/l and 5 g acetone/l, while  C. beijerinckii BA101 produced 16 g butanol/l and 7.5 g acetone/l. Further studies were carried out on a larger scale using an optimized 6% glucose/CSW medium. In a 200-l pilot-scale fermentor,  C. beijerinckii 8052 produced 12.7 g butanol/l and 6 g acetone/l following 96 h of fermentation.  C. beijerinckii BA101 produced 17.8 g/l and 5.5 g/l butanol and acetone respectively, following 130 h of fermentation. These results represent a 40% increase in final butanol concentration by the C. beijerinckii BA101 mutant strain when compared to the 8052 parent strain. The total solvents (acetone, butanol, and ethanol) produced by C. beijerinckii NCIMB 8052 and BA101 in a 200-l fermentation were 19.2 g/l and 23.6 g/l respectively. This is the first report of pilot-scale butanol production by the solvent-hyperproducing C. beijerinckii BA101 mutant employing an inexpensive glucose/CSW medium. Received: 26 May 1998 / Received revision: 21 September 1998 / Accepted: 11 October 1998