Lecture 40 - Agricultural Microbiology Flashcards
How do multi-species community in the rumen allow ruminants to extract energy from cellulose or starch?
Ferment sugars to VFAs which is used by ruminant
What is the danger of rapidly changing the food source of a ruminant from grass to grain?
- Streptococcus bovis rapidly proliferates
- Rumenal acidosis
- Kill normal rumen flora
How can nitrifying and denitrifying bacteria be used to reduce the odor from manure?
Nitrifying turns NH3 to NO3
Denitrifying turns NO3 to N2
Why is it difficult to get nitrifying and denitrifying bacteria to grow together?
Nitrifying is aerobic. Denitrifying is anaerobic.
How do pathogens infects plant?
- Stomata
- Appressoria
- Cellulases
How do plants defend themselves against infection?
- bind receptors for PAMPs, release azalaic acid
- sense bacterial effectors, dephosphorylate RIN4
What is the main bacterial causes of vegetable soft rot?
Erwinia
What is the major virulence factor associated with Pseudomonas synringae?
spots and wilts
How do Agrobacterium infections result in the formation of plant galls?
increase auxin, triggers cell growth
Diseases associated with fungal colonization of xylem
- Ascomycetes
- Basidiomycetes
- Oomycetes
What is “rice blast”?
appressorium grows invasive hyphae into plant
Why do oomyces infections occur primarily in soggy, waterlogged soil?
It is not a true fungus
What are three common symptoms associated with viral infections in plants
- growth is stunted
- mosaic leaves
- wilt
Why is the insect pathogen BT used for insect control?
Insert BT toxin genes into plant so it can produce it.
When ingested by insects it destabilizes gut lining.
What is PGPR?
Plant growth promoting rhizobacteria that colonize plant roots and prevent wilts, rusts, and insect feeding
Name 3 PGPR bacteria
- Pseudomonas fluoresence
- Bacillus subtillus
- Paenibacillus polymyxa
Name characteristics of PGPR bacteria?
- motility
- quorum sensing
- ability to attach to roots and form biofilms
How do PGPR bacteria induce resistance?
- bacteria produces antibodies
- Bacteria induces plant innate immunity
- Bacteria outcompetes colonization by pathogens
How are bacteria involved in the phosphorous biogeochemical cycle?
It takes phosphorous in the soil and converts it to phosphate for plants
Name 3 cases where bacteria can affect the concentration of plant hormones
- Auxin
- Gibberellic acid
- Ethylene is made from ACC (bacteria produce ACC deaminase)
How can bacterial ACC deaminase be incorporated into seeds to enhance plant root growth?
Bacterially coated seeds show enhanced root growth in tomato
