Micro-organisms(or microbes for short)affect every aspect of life on Earth can be friend or foe In all environments Many beneficial aspects Related to life processes (food web, nutrient cycling. . Only a minority are pathogenic, majority are completely harmless Most of our problems are caused by microbes We couldn't live without them, but they could ive without usMicro-organisms (or microbes for short) affect every aspect of life on Earth can be friend or foe – In all environments – Many beneficial aspects – Related to life processes (food web, nutrient cycling…) – Only a minority are pathogenic， majority are completely harmless – Most of our problems are caused by microbes We couldn’t live without them, but they could live without us