Lecture 40 - Agricultural Microbiology

Question 1

How do multi-species community in the rumen allow ruminants to extract energy from cellulose or starch?

Answer 1

Ferment sugars to VFAs which is used by ruminant

Question 2

What is the danger of rapidly changing the food source of a ruminant from grass to grain?

Answer 2

1. Streptococcus bovis rapidly proliferates
2. Rumenal acidosis
3. Kill normal rumen flora

Question 3

How can nitrifying and denitrifying bacteria be used to reduce the odor from manure?

Answer 3

Nitrifying turns NH3 to NO3
Denitrifying turns NO3 to N2

Question 4

Why is it difficult to get nitrifying and denitrifying bacteria to grow together?

Answer 4

Nitrifying is aerobic. Denitrifying is anaerobic.

Question 5

How do pathogens infects plant?

Answer 5

1. Stomata
2. Appressoria
3. Cellulases

Question 6

How do plants defend themselves against infection?

Answer 6

1. bind receptors for PAMPs, release azalaic acid
2. sense bacterial effectors, dephosphorylate RIN4

Question 7

What is the main bacterial causes of vegetable soft rot?

Answer 7

Erwinia

Question 8

What is the major virulence factor associated with Pseudomonas synringae?

Answer 8

spots and wilts

Question 9

How do Agrobacterium infections result in the formation of plant galls?

Answer 9

increase auxin, triggers cell growth

Question 10

Diseases associated with fungal colonization of xylem

Answer 10

1. Ascomycetes
2. Basidiomycetes
3. Oomycetes

Question 11

What is “rice blast”?

Answer 11

appressorium grows invasive hyphae into plant

Question 12

Why do oomyces infections occur primarily in soggy, waterlogged soil?

Answer 12

It is not a true fungus

Question 13

What are three common symptoms associated with viral infections in plants

Answer 13

1. growth is stunted
2. mosaic leaves
3. wilt

Question 14

Why is the insect pathogen BT used for insect control?

Answer 14

Insert BT toxin genes into plant so it can produce it.
When ingested by insects it destabilizes gut lining.

Question 15

What is PGPR?

Answer 15

Plant growth promoting rhizobacteria that colonize plant roots and prevent wilts, rusts, and insect feeding

Question 16

Name 3 PGPR bacteria

Answer 16

1. Pseudomonas fluoresence
2. Bacillus subtillus
3. Paenibacillus polymyxa

Question 17

Name characteristics of PGPR bacteria?

Answer 17

1. motility
2. quorum sensing
3. ability to attach to roots and form biofilms

Question 18

How do PGPR bacteria induce resistance?

Answer 18

1. bacteria produces antibodies
2. Bacteria induces plant innate immunity
3. Bacteria outcompetes colonization by pathogens

Question 19

How are bacteria involved in the phosphorous biogeochemical cycle?

Answer 19

It takes phosphorous in the soil and converts it to phosphate for plants

Question 20

Name 3 cases where bacteria can affect the concentration of plant hormones

Answer 20

1. Auxin
2. Gibberellic acid
3. Ethylene is made from ACC (bacteria produce ACC deaminase)

Question 21

How can bacterial ACC deaminase be incorporated into seeds to enhance plant root growth?

Answer 21

Bacterially coated seeds show enhanced root growth in tomato