Batch and continuous cultivation of Anaerobiospirillum succiniciproducens were systematically studied for the production of succinic acid from whey. Addition of 2.5 g l(-1) yeast extract and 2.5 g l(-1) polypeptone per 10 g l(-1) whey was most effective for succinic acid production from both treated and nontreated whey. When 20 g l(-1) nontreated whey and 7 g l(-1) glucose were used as cosubstrates, the yield and productivity of succinic acid reached at the end of fermentation were 95% and 0.46 g (1 h)(-1), respectively. These values were higher than those obtained using nontreated whey alone [93% and 0.24 g (1 h)(-1) for 20 g l(-1) whey]. Continuous fermentation of A. succiniciproducens at an optimal dilution rate resulted in the production of succinic acid with high productivity [1.35 g (1 h)(-1)], high conversion yield (93%), and higher ratio of succinic acid to acetic acid (5.1:1) from nontreated whey.

Korean food wastes were anaerobically digested to produce volatile fatty acids (VFA) that can be used as a carbon source in biological nutrient removal in a sequential batch reactor (SBR). Acetate, propionate and butyrate were produced at a yield of 379±400 g VFA/kg VS 0 (initial volatile solids). The ratio of SCOD (Soluble Chemical Oxygen Demand) of VFA to ammonia nitrogen (N) was in the range of 36.2±36.5 and the ratio of SCOD to phosphorus was between 151 and 162. The removal rate of nitrogen and phosphorus improved from 44% and 37% to 92% and 73%, respectively when the VFA were added to the in¯uent of the Taejon municipal wastewater plant. The concentration of nitrogen and phosphorus were maintained below 3 mg/l and 1 mg/l, respectively. The N-and P-content of the food waste was low enough not to in¯uence the ®nal N-and P-concentrations of the wastewater.

Periodic backflushing of tubular ceramic membrane filters with filtrate was employed to alleviate membrane fouling in a bioreactor with internal-filtration. As the model system, yeast fermentation was dealt with in this study. There existed optimum backflushing interval and time to give a maximum flux recovery. At 16 g/l of yeast cell concentration, the mean flux increased about 2.5 times by using such repeated operation cycles as consisted of 4.53 minutes for filtration, 4.5 seconds for intermission, and 40 seconds for backflushing. Effects of aeration, agitation speed, and yeast cell concentration were also investigated.

An internal membrane-®ltration bioreactor system with periodic fouling removal and on-line cell measurement was employed for long-term continuous ethanol production from glucose in order to prove its performance and practicality. The bioreactor system developed in this study was successfully operated for 2 months with no problems in the maintenance of ®ltration ux. The maximum productivity obtained in this study was about 13 g/l-h which was ca. 3.3 times higher than that obtained in a conventional chemostat without cell retention by membrane. In another run of continuous culture, the laser turbidimeter used for the on-line monitoring of cell concentration showed a stable performance for 45 days without sensitivity loss due to fouling.

Vancomycin-resistant enterococci (VRE) have emerged as important nosocomial pathogens since 1988. We report here an outbreak of VRE between April 1997 and May 1997 in our neonatal intensive care unit (NICU). All isolates from four patients were identified as Enterococcus faecium positive and were resistant to vancomycin and teicoplanin. All of the patients with VRE were isolated for at least 5 d after admission to the unit and the positive cultures lasted between 13 and 31 d. There were no cases of sepsis or mortality in the patients with VRE. Two cases had previously received vancomycin therapy. All isolates were shown to have the vanA gene and had the same band pattern on repetitive PCR. After the four episodes, all equipment used to care for the patients were decontaminated and the staff engaged in therapy used disposable gloves and gowns. There were no more episodes. However, the NICU is no longer a safety area with regards to vancomycin-resistant enterococcal infection.