Lecture 16 Flashcards
How can resource competition inhibit pathogen growth?
beneficial microbes dominate the nutrient and space resources
How can a healthy, balanced soil microbiome suppress pathogens?
competitive exclusion
- maintains plant health without the need for chemicals
How does colonization resistance form a biological defense?
beneficial microbes can colonize plant roots to form a protective barrier
- physically blocking pathogens from accessing root tissue
How can nitrogen-fixing bacteria help pathogens survive?
converts atmospheric nitrogen into forms that plants can use
- higher nitrogen levels can benefit plants that may impact pathogens
- some pathogens need specific nutrient conditions
How does production of antimicrobial compounds indirectly benefit plants?
reducing pathogen load
- release natural antibiotics that suppress pathogen growth
How can pH and soil chemistry modulation affect pathogens?
pathogens have optimal pH range for growth
What is the impact of soilborne pathogens on crop health and yield?
- disease development and spread: can cause root rot, damping-off, wilt = damaged roots and limited nutrient and water uptake = reduced yields
- economic losses: reduction in crop yield = loss for farmers and food supply chains
- environmental impact: pathogen control can lead to chemical interventions = negative impact on soil health
How do soilborne pathogens interact with the microbiome?
- microbiome diversity and balance
- natural disease suppression
- pathogen evolution and resistance
What are some management strategies to balance soil health and pathogen control?
- biological control: other organisms can outcompete pathogens for resources or produce compounds that inhibit pathogen growth
- crop rotation and crop selection: alternating crops and interrupt life cycle of pathogens
- soil amendments and organic matter: healthier soil with high organic matter helps retain moisture and nutrients = favor beneficial microbes over pathogens
- reduced chemical inputs: protects soil microbiome and long-term resilience against pathogen
- breeding and genetic resistance: can reduce need for soil treatments and help maintain ecosystem health by minimizing chemical inputs
How can water be beneficial for bacterial growth?
1) Nutrient transport: water dissociates and transport nutrients
2) Metabolic reactions: all biochemical reactions need water (solvent)
3) Cellular Structure and Function: maintains integrity of their cell membranes and the structure of their internal components
4) Hydration and motility
5) Ideal growth conditions: prevents drying out
What is the role of microorganisms in water quality?
transmission of infectious diseases
- pathogens can be transmitted to humans in drinking water with feces
What are some diseases that can be caused by drinking feces water?
- typhoid fever
- cholera
What is the purpose of soil and water treatment?
1) prevents pathogen contamination
2) helps with nutrient overload
3) prevents pathogens from transferring from irrigated water to crops and eventually to people
4) prevents vectors (insects) from breeding in contaminated environments
How do indicator organisms work, specifically coliforms?
used to detect fecal contamination of water
- aerobic or facultatively anaerobic, gram negative, non endospore forming rods
- ferment lactose with acid and gas within 48 hours at 35C
- Escherichia coli
How is presence of coliforms determined?
- most probably number method
- membrane filtration method
- media containing ONPG and MUG
