Module 9: Soil Environments

• primary producer is plants
• soil has aerobic and anaerobic zones
• how does water content affect soil zones?

  less water content means smaller anaerobic zones
• what microbes are present in soil?

  bacteria, fungi and protozoa-vary based on pH and salinity
• aerobic bacteria and fungi secret extracellular cellulases that degrade cellulose
• exoglucanases: degrade cellulose from ends
• endoglucanases: cut internal amorphous regions
• beta-glucosidases: degrade olligosaccharides
• anaerobic bacteria and fungi produce cellusomes
• cellusomes have a scaffoldin protein with carbohydrate binding molecule that attaches to wall, cellulose degrading enzymes attach to scaffoldin
• the main wood lignin degraders are fungi
• most common wood degraders are basidomycetes: white rot fungi
• lignin degredation: polymer attached by free radicals
• first step of lignin degredation: oxidative attack by enzymes using peroxode
• in lignin degredation generated aromatics are decayed, reduced to phenolics, and phenolics are degraded