Food Micro Exam 1

What are the three main families of aerobic spore forming bacteria

alicyclobacillus, bacillus, geobacillus

what is the main anaerobic spore forming bacteria family

clostridium

how are spore forming bacteria cells and spores similar and different

they are the same species, different pheotype,bacteria cells are active (metabolizing, multiplying) spores are dormant

how can we see spores under microscope (three methods)

malachite green stains stains spores green, clear under gram staining, phase contrast microscope-no staining required

basic characteristics of bacterial spores

Dormancy and longevity, resistance to deleterious factors (heat, freezing, lack of water, air/no air, antimicrobial agents

what type of transformation is sporulation

preservation process (one cell = one spore)

what triggers sporulation

sublethal stress ( an exposeure that damages or alters cell but does not kill it

what does a bacterial cell start as in sporulation

chromosome, peptidoglycan, cytoplasmic membrane

what are the steps of sporulation

DNA replicates, formation of septum, dividing into mother and small compartment (both with chromosome), cytoplasmic membrane invaginates to form spore septum, forespore is engulfed, forespore forms, cortex forms, coat layers form and mature, spore either releases or doesn’t (both are mature spores)

how long does sporulation take and how many genes does it require

6-7 hours, requires regulation of more than 50 unique genes to manage spore formulation

structure of spores

core, inner membrane, core wall, cortex, inner coat, outer coat, (optional exosporium)

what is the spore core made out of and why is it so important

DNA, ribosomes, enzymes, dipicolinic acid, cations, small acid soluble proteins, so important because if the core is damaged the spore will die

what is spore inner membrane made of

forespore-derived membranewh

what is spore core wall and cortex made of

peptidogylcan

what is important about the formation of the spore cortex

when it forms, it squeezes water out of core to contribute to heat resistance, and it keeps water out of the core

what are the spore inner and outer coat made of

inner: thinner protein

outer: thick layer, cysteine-rich

what are the steps in germinating a spore

activation, germination, outgrowth

what happens in the activation step of germination and what are the characteristics at this stage

either sublethal heat, low pH, or chemical or enzyme treatment, still reversible, spore retains its dormancy and resistance mostly

what happens in the germination step of germination and what are the characteristics at this stage

once germination receptors sense right germinants, they become active and initiate germination, irreversible, goes from phase bright to phase dark, loss of heat resistance (core hydration, release dipicolinic acid

what happens in the outgrowth step of germination

emergence from the spore coats and cortex, elongation of the emergent cell

what is the importance of exogenous nutrients during the outgrowth of germination and after

not required to support outgrowth, required later for development and multiplication of bacterial cells

what are the factors of resistance in spores

cell characteristics (ie optimum growth temp), sporulation conditions

review role of spore structures in resistance to processing table

yes

difference between wet and dry heat

dry heat is applied at the highest possible temp with no steam-damages proteins, dna and other core components

wet heat is milder, damages enzymes and other proteins(proteins need water to be denatured)

how do radiation,mutations, and lytic enzymes do damage to spores

radiation damages dna, le degrades peptidoglycan of the cortex, can do mutations to weaken the components

relationship between vegetative and spore resistances to heat

higher resistance to heat as vegetative correlates to higher resistance as spore

what are the two types of controls for spores in food

inactivation

-severe heat (retort or autoclave)

-gamma radiation (dry ingredients

-hydrogen peroxide high [ ] +heat (packaging)

-ethylene gas, chlorine, ozone, hurdles

Inhibition

-of germination or outgrowth(sporostatic)

-bacteriocin-nisin

-nitrite (Meat)

what are the five important aerobic spore formers and their importance in food

alicyclobacillus spp. (acidophile) spoilage

-flat sour in food package

-fruit juices and iced tea

bacillus cereus (facultative anaerobe) intoxication

-cooked rice, pasta, meats, soups, salads, puddings

bacillus coagulans (facultative anaerobe) spoilage

-flat sour

-canned tomato juice and other acidic foods

bacillus subtilis (obligate aerobe) spoilage

-“ropy” bakery product

-softening of pickles

geobacillus stearothermophilus (facultative anaerobe) spoilage

-flat sour

-low acid canned vegetables

what are the 4 most important anaerobic spore formers and their importance in food

clostridium sporogenes (strict anaerobe)

-swelling and putrid odor

-canned food

clostridium botulinum (strict anaerobe neurotoxins) intoxication

-home-canned foods

-faulty processed canned food

-temp abused, vacuum-packed low-acid food

clostridium perfringens (air tolerant anaerobe) infection

-meat and poultry product

clostridium tyrobutyricum (abundant gas) spoilage

-gas formation at late stage of cheese ripening

what define firmicutes

strong skin- cells with strong wall= gram positive

what is the main difference between firmicutes and proteobacteria

gram neg. (proteo) has lipopolysaccharidewh

what are the main components of the cell envelope of firmicutes

cytoplasmic membrane with protein, peptidoglycan, membrane lipoteichoic acid, cell wall with teichoic acid, cell wall specific polysaccharide

what is peptidoglycan made out of

amino acids and glucose-based carbohydrates

how is wall teichoic acid different from lipoteichoic acid

WTAs are covalently bound to PG by a phosphodiester linkage

LTAs are anchored to the cytoplasmic membrane by a glycolipid

what are the 6 genus of firmicutes

enterococcus, lactobacillus, pediococcus, leuconostoc, lactococcus, streptococcus

what are the main characteristics of lactic acid bacteria

gram positive, non-spore forming, catalase negative, acid tolerant, nutritionally fastidious (cannot digest everything), anaerobic but most are air tolerant, fermentative metabolism

difference between homolactic and heterolactic

fermentation process only produces lactic acid vs produces lactic acid AND ethanol and CO2eq

equation of homolactic fermentation of glucose

glucose——> 2 lactic acid + 2 ATP

which genus do homolactic fermentation

lactococcus, streptococcus, pediococcus, some lactobacillus

which genus do heterolactic fermentation

leuconostoc

some lactobacillus

difference between anaerobic vs aerobic heterolactic conditions

ana: glucose—→ 1 co2 + 1 lactic acid + 1 ethanol + 1 atp

aer: glucose + O2 —→ 1 co2 + 1 lactic acid + 1 acetic + 2 atp

difference between L and D lactic acid

L: human body

D : body doesn’t do well with

memorize the table of genera of lactic acid bacteria

enterococcus is a lactic acid bacteria

lactic acid bacteria in fermented foods

what are some health benefits of lactic acid bacteria

probiotics-ingested living microorganisms to improve intestinal ecosystem (lactobacillus reuteri, lactobacillus acidophilus)

antimicrobials used as protective cultures

health hazards of lactic acid bacteria

human and animal diseases

differentiated with how they induce immune response and the way they breakdown blood cells

what are the three types hemolysis results

ɑ (alpha): breaks down red blood cells but not hemoglobin

฿ (beta) breaks down red blood cell AND hemoglobin

ʏ (gamma) does not break down either way

how did the lancefield grouping improve grouping of hemolytic streptococcus spp.

combines immune response and hemolysis

serologic grouping of carbs in cell envelope was usedwh

what is serology

diagnostic examination of blood serum with regard to the response of the immune system to pathogens or introduced foreign substances

when the animal/human is infected with a microorganism . . .

how can two species have the same typical hemolysis but in different lancefield groups

react to different antibiotics

different immune responsed

diseases caused by streptococcus spp.

m

other disease caused by streptococcus spp.

GAS group A streptococci skin and throat infections

what defines bacteria

single cell microorganism

every expression of life has to be expressed by that single cell

no nucleus

no membrane bound organelles

what defines fungi

single cell, multicellular filamentous or macroscopic

contains membrane bound organelles and nucleus

heterotrophic nutrition

what is included in phenotyping for bacteria

morphology (visual and microscopic)

biochemical characteristics

physiology (anaerobe vs aerobe)

what is included in genotyping of bacteria

genetic relatedness or dna homology

is there a correlation between cell morphology and colony morphology

no

difference between dna and rna

rna has uracil instead of thymine

rna is single strand, instead of double

dna has deoxyribose sugar instead of ribosedi

difference between bacteria and eukaryotic cell gene expression

importance of ribosomal RNA in genetic relatedness

is called a molecular clock because it can be used to estimate when evolutionary changes transitions took place in living organisms

what is the most useful gene in bacterial identifiication

16S rDNA (gene that encodes 16S rRNA)

characteristics of prokaryotic ribosome

made of ribosomal rna and proteins

size: 70 S (sedimentation coefficient)

contains large subunit (50S) and small subunit (30S)

16S rRNA is apart of small subunit

what is the cell envelope of gram negatives made of

lipid A

core oligosaccharide

o antigen

domain, family and family of most gram negatives

Bacteria, proteobacteria, enterobacteriaceae (intensines, rod)

characteristics of enterobacteriaceae

gram neg

rod shaped

motile by peritrichous flagella

mesophiles (opt temp 22-35 C)

facultative anaerobes

respiratory and fermentative metabolism (reduce nitrate to nitrite)

carbohydrate metabolism by aerobic respiration in bacteria

what is the oxygen alternative in the tca cycle

NO3 as the final electron acceptor for anaerobic respiration

what does it mean to be a facultative anaerobe

will use oxygen to produce energy when it is present, but can als switch to fermentation in the absence of oxygen

match the type of organism to its type of CHO metabolism

aerobic- aerobic respiration

anaerobic- fermentation

facultative anaerobic- anaerobic respiration

what is the big difference between fermentation and aerobic respiration in terms of carbohydrate use

fermentation cannot be lazy and must use/consume a lot of carbohydrates to continue to produce energy

aerobic respiration can be lazy and slower with its carb intake

know the type, final electron acceptor, end product and relative energy produced for aerobic respiration, fermentation, anaerobic respiration

catalase, oxidase and ecology and host range of enterobacteriaceae

catalase pos

oxidase neg (cytochrome C oxidase, HAVE quinol oxidases)

soil, water, vegetation, common in intestinal tracts, human animal and plant pathogens

what are the 8 need to know enterobacteriaceae genera of significance in food

citrobacter, enterobacter, erwinia, escherichia, klebsiella, salmonella, shigella, yersinia

what are coliforms

coli-like organism

what is the domain phylum and species that means false unit

bacteria, proteobacteria, psuedomonasw

what is the main characteristic of psuedomonas spp

polar flagella

other characteristics of psuedomonas spp.

gram neg, rod shaped, motile by polar flagella,

catalase pos, usually oxidase neg

respiratory metabolism

many species are obligate anerobes

catabolic diversity

what type of pigments may psuedomonas secrete

pyoverdine- yellow-green

pyocyanin-blue (detection of food spoilage)

prevalence of psuedomonas spp

freeliving in soils, fresh water and marine environments

associated with plants and animals as normal biota or as disease causing agents

bioforming capabilities

steps in biofilm formation

initial reversible attachment

permanent attachment by anchoring and adhesions

bacteria multiply and form microcolonies

growth and maturation through quorum sensing

dispersion and detachment back to free floating

significance of biofilm formation

equipment contamination-control is difficult

continuous source of spoilage

difficult to remove by washing and sanitation

problematic pseudomonas spp to remember for spoilage and pathogenic

spoilage- pseudomonas fluorescens

pathogenic-pseudomonas aeruginosa

foods spoiled by pseudomonas spp

meat and poultry-odor, color, slime

raw milk-lipases that degrade milk fat, proteases that degrade milk proteins, bitterness, ropiness

pasteurized milk-will kill pseudomonas but not the products created

spoilage lingers past cooking/processes

butter-surface taint, rancidity, odor, black discolor

vegetables-slime from pectin

fish and ground meat- sulfide-like odor from cysteinem

morphology of yeast

on agar looks like bacteria

microscopically much larger than bacteria

three types of fungi

yeast, mold, mushrooms

example of good bad and ugly yeasts

good

dough leavening

saccharomyces spp

bad

skin rash cutaneous candidiasis

candida spp

ugly

pickle spoilage

zygosaccharomyces

morpholgy of mold

large and fuzzy mycelium on agar, many colors

microscopic- filamentous, thread like strands called hyphae

three types of hyphae and are they septate or nonseptate

p- septate

r-non

a-septate

example of beneficial spoilage and pathogenic filamentous fungi (molds)

mold ripened cheese

penicillium spp

moldy bread

rhizopus spp

ringworm

microsporum

morpholofy of mushrooms

example of an edible mushroom and poisonous

-agaricus spp

-amanita spp

where do fungi fit into domains of life

under eukaryota

phylogenetically distant

how are bacteria and fungi different in cell structure

fungi is eukaryotic, has membrane bound nucleus, has complex internal organelles

bacteria is prokaryotic, no nucleus, no mem bound organelles

general characteristics of fungi

eukaryotic- multi-chromosome nucleus

heterotrophic or hypotrophic, rare autotrophic

majority obligate aerobes

cell wall structure of fungi

chitin, glucans and/or mannans, glycoproteins

all cross-linked

structure of chitin vs peptidogylcan

structure of ergosterol vs chloesterol

propogation of fungi

binary fission (rare)

budding

elongation of hyphae

fragmentation of hyphae

formation of spores

• asexual

• sexual

sexual vs asexual reproduction process

starting vs ending chrom

mitotic- two—> two per

meiotic two—> one per