Originally published by Chapman & Hali in 1995 Softcover reprint ofthe hardcover lst edition 1995 Typeset in 10/12pt Times by Cambrian Typesetters, Frimley, Surrey Cover photograph is a scanning electron micrograph of Lactococcus lactis subsp. lactis Bu2-60. (Courtesy of Horst Neve, Kiel, Germany.) ISBN 978-1-4613-7666-8 ISBN 978-1-4615-5817-0 (eBook)