Soil Microbiology Flashcards
(18 cards)
What is soil microbiology?
The study of microorganisms in soil and their roles like improving soil structure, recycling nutrients, nitrogen fixation, and controlling pathogens.
What are the main ecosystem services of soil microbes?
Improving soil structure, recycling nutrients, nitrogen fixation, and controlling pathogenic bacteria.
What technique is used to study soil microbial populations?
Buried slide technique.
What type of bacteria are dominant in control soil samples?
Bacillus and Pseudomonas.
What yeast dominates in low-nutrient control soil?
Basidiomycetes yeast.
Which soil treatment shows the greatest microbial population?
Soil treated with starch.
What microorganisms thrive in starch-treated soil?
Actinomycetes (Streptomycetes, Nocardia), Bacillus, Pseudomonas, Staphylococcus, Streptococcus, Basidiomycetes, Ascomycetes.
What is the role of starch in soil?
Provides carbohydrates; initially decreases stability of organic compounds but later stabilizes, increasing organic matter.
Which microorganisms flourish in urea-treated soil?
Alcaligenes, Pseudomonas, Bacillus, Basidiomycetes, Ascomycetes.
What is the role of urea in soil?
Serves as nitrogen source and organic matter, increasing microbial activity.
What bacteria forms root nodules in legumes?
Rhizobium.
What is the role of Rhizobium in legumes?
Fixes atmospheric nitrogen, increasing crop protein content.
What enzyme system allows nitrogen fixation?
Nitrogenase enzyme system.
How do nitrogen-fixing bacteria interact with host plants?
They invade root hairs, multiply, and form root nodules.
Which organisms are ammonia oxidizers?
Nitrosomonas, Nitrosobacter, Nitrosolobus, Nitrosovibrio, Brocardia.
Which organisms are nitrite oxidizers?
Nitrobacter, Nitrospira, Nitrococcus.
Which organisms are dissimilatory nitrate reducers?
Alcaligenes, Escherichia, Aeromonas, Enterobacter, Bacillus, Flavobacterium, Nocardia, Spirillum, Vibrio, Staphylococci.
Which organisms are denitrifiers?
Pseudomonas, Rhodopseudomonas, Azospirillum, Thiobacillus, Propionibacterium, Paraccocus.
