The aim of the present work was the development of phosphorylcholine-based treatments for biofiltration membranes and the demonstration that such treatments prevent or inhibit protein fouling. Microfiltration membranes of cellulose triacetate, polyether sulphone and polyvinylidene fluoride were etched with oxygen in a plasma chamber to generate surface hydroxyl groups and were then treated with the monomer 2-methacryloyloxyethyl phosphorylcholine. These membranes were evaluated with water, buffer, bovine serum albumin (BSA), yeast fermentation broth, beer and orange juice. The treatment of cellulose triacetate membranes reduced both the initial flux and the extent of water fouling. In terms of the integrated flux, these factors tended to cancel each other out. For protein, the membranes gave similar or higher fluxes but worse fouling. The cellular feed (yeast) reacted more favourably to the coating than the BSA. The polyether sulphone was scarcely affected by the coating; fouling remaining high with most 'real' feeds. There was lower initial flux but less flux decline with water and beer. Washing with water and cleaning with Tergazyme did not restore the initial flux. Polyvinylidene fluoride membranes gave the most positive results. In most cases, the coating both increased initial flux and decreased the rate of fouling. The coating was particularly effective for BSA and for beer and orange juice, where fouling is probably caused by a polysaccharide rather than by a protein. Electron microscopy showed, nonetheless, that fouling by proteins was accompanied by protein adsorption primarily on the upper surface of the membrane and that coated membranes showed less deposition and in different places than did untreated membranes.

SUMMARYA nisin-sensitive strain of Pediococcus sp possessed an uptake system for K + which was apparently dependent on metabolic energy and ATPase activity. K + uptake rate was dependent on the glucose and K + eoncentratious and showed approximately Michaelis-Menten kinetics with respect to both of these variables with K t values of 1.2 mM and 599/xM respectively.The presence of nisin inhibited K + uptake with the percentage inhibition proportional to the nisin activity,. Total inhibition occurred at between 4.5 and 5.0 IU ml ~ and the MIC was approximately 0.6 IU ml -l.

SUMMARYAddition of nisin to a K+-loaded, metabolising suspension of Pediococcus sp resulted in K + efflux into the medium. The total K + efflux was proportional to the logarithm of the nisin activity with a MEC of 0.7 IUml "~ and resulted in total loss of cellular K + at 4-5 IUml nisin. Conditions were optimised for the use of K + efflux measurements as a rapid nisin bioassay using a combination of factorial and sequential simplex proeedures. A nisin assay based on K + efflux measurements was used to follow the course of a nisin-producing fermentation.

The SGI Ultrafermenter is an external loop bioreactor with circulation through an ultrafiltration module allowing removal of medium and soluble products during fermentation. The contents are continually circulated during operation and the vessel is also equipped with a stirring turbine. The interaction of these two mixing agents on gas transfer was investigated. Both mechanisms produced similar increments in KLa over their working ranges, with values from approximately 0–700 h−1 at 200 dm3 h−1 airflow. The effects of these two mechanisms on KLa were approximately additive at low values but the combined mixing produced a maximum KLa value also in the region of 700 h−1. The power‐draw of mixing using the two agents was calculated and stirring was found to be 10–20 times more efficient than circulation.

9. . This book was not written by microbiologists but it does give many interesting insights into current thinking around biological warfare. It is divided into two sections. The first section contains case studies of the use or alleged use of chemical/ biological weapons (CBW). These case studies include, among others, the US anthrax letters, the Yellow Rain affair and Japanese germ warfare, as well as an overview. The second section covers policy and scholarly implications from both a US and UK perspective and a conclusion on possible future biosecurity policies.The book is well referenced and has been carefully written and edited. A good example of this is the conclusion to Chapter 4: The Yellow Rain Affair by Matthew S Meselson and Julian Perry Robinson:"The lessons to learn from the Yellow Rain episode are straightforward: reliable procedures must be used to acquire and evaluate interview evidence, including the use of corroborative crosschecks and double-checks and careful avoidance of leading questions. Chemical identification of trace components must adhere to appropriate standards for forensic analysis, and results must be corroborated by an independent laboratory. Hypothesis must be subjected to wide consultation and objective criticism. Failure to apply these lessons, whether through incompetence or because of political exigencies and pressures, imperils the credibility of subsequent investigations of situations in which CBW weapons may actually have been used."This conclusion is a good reason for reading this book.