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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 12

Các enzyme của vi sinh vật và các hoạt động của họ đã được nghiên cứu chủ yếu trong nền văn hóa lỏng tinh khiết trong điều kiện phòng thí nghiệm. Tuy nhiên, trong môi trường tự nhiên, vi sinh vật phát triển với giao diện như đính kèm (không cuống) cộng đồng hỗn hợp chứ không phải là quần thể sinh vật phù du như bị đình chỉ (1). Nghiên cứu các enzym vi sinh vật trong đất một số cách để công nhận này, nhưng giải thích dữ liệu đã thường bị khó khăn bởi vì các phương. | 12 Microbes and Enzymes in Biofilms Jana Jass Umea University Umea Sweden Sara K. Roberts University of Illinois-Chicago Chicago Illinois Hilary M. Lappin-Scott Exeter University Exeter England I. INTRODUCTION Microbial enzymes and their activities have been studied primarily in pure liquid cultures under laboratory conditions. However in natural environments microorganisms grow at interfaces as attached sessile mixed communities rather than as suspended planktonic populations 1 . Studies of microbial enzymes in soil go some way to recognizing this but data interpretation has often been difficult because the methodologies do not easily differentiate between enzymes associated with surface-attached populations and those loosely attached or free in the liquid phase. It is the aim of this chapter to discuss the biological characteristics of these sessile microbial populations with particular reference to their enzyme activities. II. WHAT IS A BIOFILM Microorganisms attached to a surface are collectively referred to as a biofilm and are of current interest because they are different in their phenotype and physiological characteristics from the planktonic populations. Early research on biofilms was conducted in the 1920s and 1930s primarily by Claude ZoBell 2-4 who was one of the first people to note that bacteria existed as what he termed attached films. Three of ZoBell s many observations 3 4 include that bacteria attach rapidly to surfaces planktonic bacteria are not covered in sticky material but sessile bacteria are and these organisms once associated with a surface secrete a cementing substance. It is significant that many of the problems encountered by biofilm researchers today are the same as those from as long as 60 years ago they include understanding the mechanisms underlying attachment detachment 3 microbial interactions population diversity biofilm structure and growth 5 . There have been many proposed definitions of a biofilm over the years 6 7 the most .