Fungi

Front 1

What are the main characteristics of fungi?

Back 1

Eukaryotes - mainly multicellular

Chitin in cell wall

Heterokaryotic stage

Form hyphae (network is called a mycelium)

Zygotic life cycle

Reproduce through spores

Non-photosynthetic

Non-motile

Heterotrophic

Macro and microscopic appearance

Mostly in terrestrial habitats (lands)

Front 2

Which reproduction is predominant?

Back 2

Asexual if conditions are favourable - less energy needed for it

Front 3

What's the main role in ecosystem of fungi?

Back 3

Decomposers - clean higher level of food chain (predators) and anything in between

Front 4

What is ecophysiolohy?

Back 4

Deals with adaptation of the physiology of an organism to environmental conditions

Front 5

What's ecophysiology of moulds?

Back 5

Fermentation

C assimilation - carbs, organic acids

N assimilation - amino acids, nitrate

Volatiles production - esters, acetaldehyde

Growth at high sugar, low aw, high salt - osmotolerance

Growth at broad pH range (2-10)

Growth at low temperature

Enzyme activities - lipolytic, pectinolytic etc.

Resistance to preservatives

Front 6

What's traditional classification based on?

Back 6

Reproductive structures

Nowadays based on philogeny

Front 7

What is holomorph?

Back 7

"whole fungus"

= anamorph (asexual reproduction) + telomorph (sexual reproduction)

*Pleomorph - has more phenotypes

Front 8

What's the simple classification of fungi?

Back 8

Zygomycetes (lower fungi)

Higher fungi:

Basidiomycetes (mushrooms)

Ascomycetes

Fungi imperfecti (deuteromycetes) - artificial phylum because sexual cycle was unknown

(deuteromycetes) - artificial phylum because sexual cycle was unknown

Front 9

What are main characteristics of zygomycetes?

Back 9

Terrestrial (but humid)

Form zygospores (sexual)

Non septated vegetative hyphae

Coenocytic (many nuclei in a shared cytoplasm)

Asexual reproduction by the formation of sporangiospores - formation sporangia

Implicated in food spoilage!!

Front 10

What are characteristic of reproductive cycle of zygomycetes?

Back 10

Mycelium of a mating type + and - (2 types of nuclei) -> gametangia with haploid nuclei -> young zygosporangium (heterokaryotic) -> karyogamy -> ...

Front 11

What are names of Rhizopus spores?

Back 11

Sporangiospores for asexual

Zygospores for sexual

Front 12

What are characteristics of Rhizopus?

Back 12

Rhizoids - root like structures

"Black bread mould" - R. stolonifer

Rhizopus oryzae - tempeh fermentation

Front 13

What are characteristics of ascomycota?

Back 13

Terrestrial (also dry regions)

Sexual spores (ascospores) contained in ascus

Septated vegetative hyphae

Sometimes asexual reproduction via conidia

Complete life cycle not always known and in that case fungi imperfecti (deuteromycetes)Food spoilage and mycotoxins!!

Eg.Aspergillus flavus

Front 14

What's the contamination pathway?

Back 14

1) sporulation

2) release of spores

3) spores distribution

4) landing and attachment of spores

Front 15

What happens in sporulation?

Back 15

Produced in asexual cycle (vegetative) - majority

Conidia - ascomycota

Sporangiospores - zygomycota

Front 16

How release of spores happen?

Back 16

Passive:

Dry - gravity or agitation (shaking, vibration)

Wet - mist pickup, rain drops

Active:

Dry - deflation (bursting)

Wet - bellows (ballistospores), hygroscopic effect

Front 17

How spores distribution happens?

Back 17

Air currents

In water

Attached to dust particles

Eddy movements

Depends on size, shape, smooth or rough surface, specific mass, electrostatical charge

Front 18

What happens after spore attachment?

Back 18

Mycelium outgrowth - hydrophobins play a role in mycelium distribution, they are surface-active molecules which lower surface tension of their aqueous environment enabling hyphae to grow into the air

-8 conserved cysteine residues

-100 a.as. long

-Self assemble at hydrophobic interfaces

Front 19

What does botyris cinerea do to grapes?

Back 19

Noble rot:

Botyris punctures healthy mature grapes skin -> increased dehydration -> elevated sugar content -> inhibition of mould growth -> SWEETER wine

Same done to not mature grapes - spoilage

Front 20

When yeasts overcomplete bacteria?

Back 20

Ecological niche for growth of moulds:

Ph < 4.5 (no bacterial growth)

Aw < 0.9 (no bacterial growth, except for halophilic)

Front 21

Why are fresh fruit perfect niche for fungi?

Back 21

Low pH (high acidity), sweet

Front 22

What happens in food with low aw?

Back 22

Below 0.9 only fungi and no bacteria - eg. In molasses, dried fruit, confections

Front 23

What happens in pasteurised products niche?

Back 23

Canned fruit, bottled fruit, cartoned fruit

-Heat resistance of ascospores (sexual spores)

-Pectolytic enzymes to break down plant tissue

Front 24

What are characteristic of byssochlamys Nivea?

Back 24

Anamorph- paecilomyces niveus

Soil inhabitant

Heat resistant ascospores

Requires inactivation temp above 90°C

Resistant to acid, chlorine and alcohol

Spoils processed fruit products

Mycotoxins: patulin

Front 25

What are techniques to combat spoilage fungi?

Back 25

High pressure processing

Ultrasound

Heat

Usually combo

Combo of sonication and heat - rapid decrease but after 10 minutes still quite a lot

HPP + heat - very good inhibitory effect

Front 26

What type of effects may occur when combining treatments?

Back 26

Additive

Synergistic (more than additive)

Antagonistic

Front 27

What happens in products with chemical preservatives?

Back 27

Fruit juice and mayo - monillela acetobutans grows in 4% acetic acid

Sliced rye bread - P. Roqueforti, aspergillus etc. grow on sorbic acid

Cheese rind - penicillium discolor resistant to natamycin

Front 28

What are mycotoxins?

Back 28

Toxic 2ndary metabolites produced by moulds

Among the most toxic compounds

Cause chronic and acute diseases, in man and animal, severe symptoms

Front 29

What are 2 most important groups of mycotoxins?

Back 29

A. Flavus - aflatoxins (infants and vegans at risk - milk and nuts)

Fusarium toxins - fumonisins, deoxynivalenol

Front 30

Where can mycotoxins be found?

Back 30

Oil seeds, milk, grains, peanuts, figs

Front 31

What are measured to control mycotoxins in food chain?

Back 31

Prevention:

GAP - good agricultural practice

Controlled storage of agricultural products

End of pipeline:

Decontamination - chemical methods (not effective), physical (moderate effective and impact on product quantity), biological (fermentation, decrease toxicity by metabolic conversion but you'll end up with a different product)

Front 32

What's the enumeration process for fungi?

Back 32

Sampling (uneven distribution, spores presence, fragmentation mycelium - impossible to count!) - measure level of chitin instead

Sample processing (dilution in 0.1%) peptone, mild heat treatment)

Plating (antibiotics, osmotic value)

Front 33

What are ways to detect fungi?

Back 33

Classical - selective plating, colony morphology, microscopy

Immunological - ELISA, latex agglutination

DNA based methods - random amplified polymorphic DNA (RAPD)(no absolute ID though), sequencing conserved regions 18S rRNA (slow, identification), RT PCR (fast, identification, presence unique genes)

Front 34

How latex agglutination test work?

Back 34

1)Mix sample with latex beads covered in antibodies

2) if target for antibodies present - latex beads will clump (agglutinate)

Qualitative not quantitative

Front 35

What part can Elisa detect?

Back 35

Immunologically active EPS - more quantitative

Negatives - also detects non living moulds and it's more detection than identification (multiple species not detected separately)

Front 36

What does government do in therms of quality assurance?

Back 36

Inspection for mycotoxins or unlawful use of mouldy ingredients, risk assessments, inform enterprise and general public - eg. Inspect factories, analyze samples

Front 37

What does public private sector do in therms of quality assurance?

Back 37

Internal monitoring among members of trade organisation, aflatoxins level controls in feed (feed manufacturers)

Front 38

What do private enterprises do in therms of quality assurance?

Back 38

Quality management, GMP, HACCP use

Front 39

Which fungi has the least complicated structure?

Back 39

Phycomyces (lower fungi)