Lecture 1 - Exam 1

Question 1

What is soil microbiology?

Answer 1

Is the study of soil microbes and their processes.

Question 2

What is soil microbial ecology?

Answer 2

Involves an evaluation of the behavior of organisms in their native habitats. Soil microbial ecologists study interrelations among microorganisms and between organisms and their environment.

Question 3

What are the two questions we try to answer in soil microbiology?

Answer 3

Whose there (we want to know the types of microorganisms and the number of microorganisms)? What do they do (their function in the soil ecosystem)?

Question 4

Microbes participate in…?

Answer 4

In almost all bio, geo chemical processes in the soil. Ex: nutrient cycling (nitrogen, phosphorous, carbon).

Question 5

Who was Antoni van Leeuwenhoek?

Answer 5

A dutch lens maker and merchant. He was the first one to observe microbes under a microscope, and constructed the very simple microscope himself. He called microbes: “little ani’malcules.”

Question 6

What was Leeuwenhoek’s microscope like?

Answer 6

Single lens and magnification of x118.

Question 7

Who was Robert Hooke?

Answer 7

He made it possible for everyone else to observe microbes.

Question 8

Who was Louis Pasteur?

Answer 8

French chemist that was known for heat sterilization “pasteurization,” disproved spontaneous generation, fermentation (wine, beer making), and vaccines (cholera, rabies).

Question 9

Who was Robert Koch?

Answer 9

German doctor that proved the microorganisms can cause diseases (Koch’s postulates) and known for his use of solid media (no agar). He also studied anthrax.

Question 10

Who was Sergei Winogradsky?

Answer 10

Russian scientist and is known as the “founder of soil microbiology.” Known for is studies in autotrophic growth.

Question 11

Who was Martinus Beijerinck?

Answer 11

Dutch biologist known as the “founder of soil microbial ecology.” He used the enrichment culture technique (to isolate pure cultures of organisms from the environment, isolated the first root nodulating bacterium, microbial transformation of C, N, Mn, etc., and his discovery of the tobacco mosaic virus.

Question 12

What is the saying in soil microbial ecology?

Answer 12

Everything is where and the environment selects.

Question 13

Who was Jacob G. Lipman?

Answer 13

Was the first one to study the effects of soil organisms on soil fertility and plant growth.

Question 14

Who was Selman A. Waksman?

Answer 14

Made the major discovery of Streptomycin that is produced by soil bacterium. It was the first antibiotic against tuberculosis, cholera, and typhoid fever.

Question 15

Who was Colwell (more recent scientist)?

Answer 15

Studied marine microbes and helped in the oil spill.

Question 16

What is a prokaryote?

Answer 16

A cell or organism lacking a nucleus and other membrane-enclosed organelles, usually having its DNA in a singular circular molecule. Ex: bacteria or archaea

Question 17

What is an eukaryote?

Answer 17

A cell or organism having a unit membrane membrane-enclosed nucleus and usually other organelles. Ex: plants, animals, fungi (considered a microbe).

Question 18

What was the old classification system?

Answer 18

Five Kingdoms: Bacteria, fungi, protista, animals, and plants. It is based on morphological, physiological, and biochemical characteristics. NOT used anymore.

Question 19

What is the new classification system? What is is based on?

Answer 19

Three domains: Archaea, Bacteria, Eukarya. It is based on phylogenetic features determined from small sequences (16S or 18S) ribosomal RNA sequences.

Question 20

In a phylogenetic tree, what is missing? What does the distance between nodes mean? What is similar?

Answer 20

Viruses are not on the tree. The distance between nodes = their evolutionary distance. Archaea and Bacteria are similar phylogenetically, but not biochemically or molecularly. Plants and animals are diverse morphologically, but genetically similar.

Question 21

What did Carl R. Woese do?

Answer 21

Discovered the archaea branch on the phylogenetic tree.

Question 22

Bacteria have what kind of linkages?

Answer 22

Ester-linkages. These are easy to break.

Question 23

Archaea have what kind of linkages?

Answer 23

Ether-linkages. This bond is stronger, so it will stay intact in harsh environments.

Question 24

What are the unique features of microbes?

Answer 24

1. Microbes are the oldest forms of life on Earth.
2. Microbes are the smallest organisms with diverse metabolism.
3. Most organisms and most kinds of organisms are microbes.
4. Microbes are everywhere.
5. Microbes have tremendous impacts on the Earth environment.

Question 25

How old is Earth? What was early Earth’s environment like?

Answer 25

4.6 billion years old. Early Earth had extreme environments. Nitrogen, hydrogen, and carbon dioxide on early Earth. Life appeared on Earth in shallow water 0.5-1 billion years after the formation of Earth and were anaerobes.

Question 26

Microbes are the smallest organisms with diverse metabolism. What is the consequence of being small?

Answer 26

Large specific surface area and high surface area to volume ratio.

Question 27

As a cell increases in size, its surface area-to-volume ratio _________. Why is this important?

Answer 27

Decreases. This is important because microbes don’t have a mouth. They have surface limited processes (diffusion) and the cells have to be large enough to hold the biochemical and machineries for cells to carry out metabolism.
Equation is surface / volume.

Question 28

Bacterial cells have S/V values ________ times higher than eukaryotic cells.

Answer 28

100-1000

Question 29

Metabolism is inversely proportional to _____?

Answer 29

Size. Small cells have higher metabolism and have a diverse metabolism, but not morphology.

Question 30

Where do Eukaryotes get their energy source? What are their electron acceptors?

Answer 30

Organic chemicals that can be broken down to glucose and get it from light (plants). Only have O2 as electron acceptor (for respiration).

Question 31

Where do prokaryotes get their energy source? What are their electron acceptors?

Answer 31

Wide range of organic and inorganic chemicals and get it from light. They use O2, NO3-, SO42-, and CO32-

Question 32

Most organisms and most kinds of organisms are microbes. How many species of microbes do we have on the human body?

Answer 32

> 10^4. We carry more microbial cells than human cells.

Question 33

What is the bacterial number and species in one gram of soil?

Answer 33

10^9 bacteria per 1 gram of soil.
There are 20,000-40,000 species in 1 gram of soil (others believe that there are one million species per 1 gram).

Question 34

Are most bacteria culturable?

Answer 34

No, 0.1-5% are culturable.

Question 35

What are the methods of diversity estimation?

Answer 35

DNA reassociation and body length vs. species number.

Question 36

What is the relationship like between the number of species and their length?

Answer 36

There is an inverse relationship.
Ex: Whales and elephants are large, and they have less species than something like insects.

Question 37

Microbes are everywhere. Can they live under extreme temperature, pressure, salinity, and radiation?

Answer 37

Yes. The lower temperature limit of life (microbes and everything else) is -20 to -30 degrees C. The upper limit is 121 degrees C and 15 Psi. Hence, some microbes can survive autoclave temps. The dead sea is 29% salinity, and Deinococcus radiodineus can tolerate up to 5,000 grey of ionizing radiation, where 60 grey would kill E. coli and 10 would kill humans.

Question 38

Microbes have tremendous impact on the Earth’s environment. What are some of those impacts?

Answer 38

Recycle nutrients, generate oxygen in the atmosphere, carry out primary production, degrade wastes and remediate contaminated soils, form mutualistic interactions w/ plants, and soil formation & maintenance of soil structure.