Lecture 24

Question 1

Extracellular polysaccharides

Answer 1

An organic material that is produced by microbes when colonizing surfaces that allows more bacteria to stick to a surface

Question 2

Biofilm

Answer 2

a film of extracellular polysaccharides (and microbes) that forms composed of only one type of bacteria trying to attach itself to a surface

Question 3

Microbial mats

Answer 3

thicker microbial films

Question 4

Microbial mats are ___ and have _____ layers.

Answer 4

thick, segregated

Question 5

Stromatolite

Answer 5

The lithified version of a microbial mat (upper part is still alive)

Question 6

Proof that there was microbial life in oceans millions of years ago:

Answer 6

microbial mat

Question 7

Microbes are sticky and reactive due to

Answer 7

EPC

Question 8

EPS

Answer 8

Extracellular layers that are located external to the cell wall

Question 9

Two types of EPS

Answer 9

capsules and sheaths

Question 10

Capsule EPS

Answer 10

amorphous layered EPS

Question 11

cheaths

Answer 11

structured layered EPS

Question 12

Deprotination

Answer 12

Cell walls/ EPS contain molecules that can release protons into the solution

Question 13

Deprotination leads to the formation of

Answer 13

organic anion or ligand

Question 14

Most important surface group to microbes

Answer 14

Carboxyls (are most abundant and most important for surface charge)

Question 15

Why bacteria is used in industrial processes

Answer 15

they are everywhere, reactive, have small surface area to volume ratio, and are good for bonding metals

Question 16

Bioremediation

Answer 16

bacteria absorb metals meaning they are used in bioremediation strategies

Question 17

Biosorption

Answer 17

process y which microbial biomass acts as a surface upon which toxic metals and radionuclides are passively absorbed

Question 18

Bioaccumulation

Answer 18

the metabolic process used by living biomass in which physiologically important metal ions are absorbed by cells

Question 19

two ways of biomineralization

Answer 19

Biologically induced biomineralization and biologically controlled biomineralization

Question 20

biologically induced biomineralization

Answer 20

occurs without any regulatory control - biominerals are produced as by-products due to the activity of the microorganism and their surrounding environment

Question 21

Examples of induced biomineralization

Answer 21

release of metabolic wastes (CO2, OH-, H+, NH3, and H2S). the release of cations by the cell, or the development of a charged surface

Question 22

Biologically controlled biomineralization

Answer 22

a completely regulated process, allowing the organism to precipitate minerals that serve physiological roles

Question 23

How induced bioremediation works with EPS

Answer 23

1. a metal binds with the cell surface of the microbe (leaving positive change on the outside)
2. those metals react with anions from the solution

Question 24

What is the most likely environment to study old bacteria and why?

Answer 24

Silicified environments - bacteria become encrusted in amorphous silica because they hydrothermal fluids are often very enriched in dissolved silica

Question 25

examples of microbes that have control over the silification process

Answer 25

diatoms (building of silica shell) and radiolarians

Question 26

Largest fraction of known biologically controlled biominerals are:

Answer 26

calcium carbonate minerals

Question 27

Calcium carbonate precipitation occurs from

Answer 27

coccolithophores and foraminifera microorganisms that remove calcium carbonate from seawater to form their skeletons

Question 28

The most important role of microbes in terms of chemical weathering is the formation of _____ via ____ or ____

Answer 28

carbon dioxide

aerobic respiration or dead organic material

Question 29

Microbes aerobic respiration equation

Answer 29

glucose+ oxygen —-> 6CO2 + 6H20 (Co2 will react with water later to make carbonic acid)

Question 30

Microbes accelerate mineral dissolution by:

Answer 30

production of organic acids

Question 31

Two ways organic acids increase mineral dissolution:

Answer 31

1. they release protons to attack minerals directly

2. they lower a mineral’s saturation state by reacting with them

Question 32

Microbes can make energy through:

Answer 32

chemosynthesis or photosynthesis

Question 33

Pyrite and microbial processes

Answer 33

Sulfur and iron are in reduced forms, they can be oxidized at the earth’s surface by microbes.

Question 34

Acid mine drainage

Answer 34

During coal and metal mining operations, waste rocks are disposed of In the form of spoil heaps or in tailings ponds. Those waste materials typically contain residues of pyrite and other sulfide minerals that are unstable upon exposure to oxygenated waters. This results in acidic and sulfate/metal-rich effluent.

Question 35

Bioleeching

Answer 35

the use of bacteria, to leach minerals such as copper, zinc, uranium, nickel, and cobalt from sulfide minerals.