Autolytic Enzymes in Growth of Bacteria

Abstract

MANY bacteria lyse when growth of the cultures ceases, irrespective of whether growth has stopped because of the exhaustion of the growth medium or the addition of toxic substances such as the penicillins to the cultures. Lysis is caused by the presence in the microorganisms of autolytic enzymes (autolysins) which specifically hydrolyse mucopeptide polymers in the bacterial cell wall. The attack occurs, at least in some species, in a very restricted area around the point at which the bacteria will divide^1,2. This has led to suggestions that the autolysins are involved in bacterial growth. Three sorts of hypotheses have been suggested. First, that the enzymes are essential to make openings in the supposedly continuous network of mucopeptides in the wall^3,4 so that the new building blocks can be added during growth^3,5; second, that the enzymes are essential for the remodelling of the wall in making the septum that divides one bacterium into two daughter cells^6,7; and third, that they are necessary to break the two newly formed bacteria apart from each other⁸.