General Characteristics Of Microorganisms Flashcards
(55 cards)
1
Q
Yeasts size
A
5-12u
2
Q
Bacteria size
A
1-2u
3
Q
Molds reproduction
A
Slow asexual-spores
Sexual cycle
4
Q
Yeasts reproduction
A
Intermediate budscars-limit
Sexual-ascus
Zygote
5
Q
Bacteria reproduction
A
Fast binary fission
Infinite
6
Q
Mold diversity
A
High
7
Q
Yeast diversity
A
Moderate
8
Q
Bacteria diversity
A
High
9
Q
Molds substrate utilization
A
High
10
Q
Yeast substrate utilization
A
Low
11
Q
Bacteria substrate utilization
A
Highest
12
Q
Molds pH
A
Acid tolerant 3-8
13
Q
Yeasts pH
A
Acid tolerant 4-8
14
Q
Bacteria pH
A
Neutral 5-10
15
Q
Molds oxygen
A
Aerobic
16
Q
Yeast oxygen
A
Facultative( growth oxygen or without oxygen)
17
Q
Bacteria oxygen
A
Aerobic-anaerobic
18
Q
Molds moisture tolerance
A
Very dry
19
Q
Yeasts moister tolerance
A
High level of water
20
Q
Bacteria moisture tolerance
A
High level of water
21
Q
Molds food spoilage
A
Low pH foods dryer foods( bread and juice
22
Q
Yeasts food spoilage
A
Low pH foods high H2O content
23
Q
Bacteria food spoilage
A
neutral pH foods high H2O content
24
Q
Molds size
A
5-12 u dia , up to 25u length
25
Fungi are an equally important group
of microorganisms in food microbiology
26
fungi are used industrial fermentation
of beer and wine, production of enzymes (e.g. rennet’s for cheese, pettiness to clarify fruit juices and wine, amylases for bread industry, etc), antibiotics, vitamins, and organic acids.
27
The baking industry and the certain types of cheese
also depend on fungal activities.
28
Some fungi are pathogens
plants, humans, or other animals. Other important fungal activities include the decay of complex plant and animal remains or environmental pollutants.
29
Fungal pathogens cause
Fungal pathogens cause
30
Potato blight fungus
Phytophthora infestans, Ireland 1840, 1 million died of starvation, an equal number of people were forced to emigrate to the U.S. or Europe.
31
Great Bengal Famine
1943, 2 million died of starvation due to a severe outbreak of Helminthosporium oryzae on the rice crops.
32
Molds
are filamentous fungi
33
The individual filaments called
hyphae and the mass of these filaments is termed a mycelium
34
mycelium
is a multinucleate mass of cytoplasm enclosed within a rigid, branch system of tubes
35
mycelium
These tubes represent a protective structure that is homologous to a cell wall of a unicellular organism.
36
A mycelium usually arises
from the germination and outgrowth of a single reproductive cell, or spore
37
Upon germination
the spore puts out a long threadlike hyphae which branches repeatedly as it elongates to form the mycelium
38
The hyphae of higher molds are compartmentalized
by membrane divisions called septa
39
septa
are usually perforated and allow passage of cytoplasmic fluid and even nuclei between different parts of the hyphae.
40
yeast are
nicellular fungi that multiply by budding or by binary fission (like many bacteria)
41
Some fungi are dimorphic
they are molds under certain environmental conditions and yeast-like at others (e.g. Candida albicans, M at 20-25oC and Y at 37oC).
42
fungi
eukaryotic
43
fungi reproduce
by both sexual or asexual means, but in either case spores are usually produced.
44
Sexually produced spores
are derived from the nuclei of parental cells
45
the parent and the spores
haploid
46
Two nuclei from the parental cells fuse to form
diploid zygote nucleus
47
Haploid spore nuclei are derived from
reductive nuclear division (meiosis)
48
most common habitat of Molds
habitat is soil and spores are widely dispersed in dust.
49
Physiologically fungi
more adaptable to severe environmental stress than other microorganisms
50
fungi more adaptable to
They are more tolerant to osmolarity extremes (osmophiles spoil syrup and jams), pH (acidophiles - acid tolerances range within strains or species from pH 1.8 to 8.0), and drying (xerophiles - some can grow at aw
51
Molds are strictly
aerobic (discuss Ca2+ lactate on cheese) but Yeasts can utilize sugars such as glucose anaerobically (fermentation) or aerobically (respiration)
52
under anaerobic conditions yeasts
the major end products of yeasts are ethanol and carbon dioxide via the alcoholic fermentation
53
under aerobic conditions yeasts
complete oxidation of glucose by yeasts accumulates acids, alcohols, esters, glycerol, aldehydes and other products.
54
Fungi exhibit a wide growth temperature range
but 20 to 30oC is optimal for most species
55
Some fungi can grow at
0oC and a few thermophilic molds grow as high as 62oC.
