BACKGROUND: Oral therapy with phenylalanine ammonia lyase (PAL), naturally encapsulated in plant cells, may provide a potential alternative treatment for hyperphenylalaninemic patients, including those with phenylketonuria. Therefore different sources of plant tissue were investigated for PAL activity.

The retention of phenylalanine ammonia-lyase (PAL) activity in Red Spring wheat seedlings during storage and in vitro protein digestion was evaluated toward assessing the efficacy of plant PAL as a dietary supplement for patients suffering from the metabolic disease, phenylketonuria. Retention of PAL activity in freeze-dried wheat seedling tissues following three months of storage at -20 degrees C ranged from 62% in the leaf to 89% in root/residual seed tissues. After a 3-h two-stage ("gastric-intestinal") in vitro digestion, 36% and 42% recovery of PAL activity was associated with chopped fresh leaf and root/residual seed tissues respectively; however, no activity was recovered from freeze-dried tissues. High performance liquid chromatographic analysis of the residual phenylalanine (Phe) after in vitro digestion confirmed that the fresh tissues effected a significantly higher conversion of exogenous Phe than freeze-dried tissues. These results demonstrate that the plant cell walls provide protection of PAL during in vitro digestion. In cases where exogenous Phe (100 mg; 24 mM) was supplied to the tissues, the product of the reaction, trans-cinnamic acid, may have exerted a significant inhibitory effect on PAL activity.

Aims: The use of microbial fuel cells (MFC) to treat winery wastewater is promising; however, an initial acidic pH, fluctuating chemical oxygen demand (COD) levels and a lack of natural buffering in these wastewaters make providing a suitable buffer system at an ideal buffer to COD ratio. Methods and Results: A lab scale MFC was designed, inoculated with anaerobic winery sludge and fed with synthetic winery wastewater. It was observed that at pH 6Á5, the MFC performed best, the maximum output voltage was 0Á63 AE 0Á01 V for 60 AE 3 h, and the COD removal efficiency reached 77 AE 7%. The electrogens were affected by pH much more than the bulk COD degrading organisms. Fluorescent in situ hybridization suggested Betaproteobacteria played a significant role in electron transfer. Conclusions: A ratio of 1 mmol l −1 phosphate buffer to 100 mg l −1 COD was ideal to maintain a stable pH for MFCs treating synthetic winery wastewater. Significance and Impact of the Study: The results find the narrow pH tolerance for MFCs treating winery wastewater and demonstrate the significance of pH and buffer to COD ratio for steady performance of MFCs.