slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Yoon-Hee Lee Dep. of Food Science & Technology PowerPoint Presentation
Download Presentation
Yoon-Hee Lee Dep. of Food Science & Technology

Loading in 2 Seconds...

play fullscreen
1 / 17

Yoon-Hee Lee Dep. of Food Science & Technology - PowerPoint PPT Presentation


  • 98 Views
  • Uploaded on

Y easts and M olds - Using selective media; examining fungi morphology. Yoon-Hee Lee Dep. of Food Science & Technology. FUNGI VS. BACTERIA. Fungi ۰ Larger ۰ Eukaryotic ۰ Aerobic ۰ Slow growth ۰ Grow in both acidic and basic condition ۰ Filamentous - Mycelia. Bacteria ۰ Smaller

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Yoon-Hee Lee Dep. of Food Science & Technology' - marsha


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

YeastsandMolds

- Using selective media; examining fungi morphology

Yoon-Hee Lee

Dep. of Food Science & Technology

TheOhioStateUniversity

slide2

FUNGI VS. BACTERIA

Fungi

۰ Larger

۰ Eukaryotic

۰ Aerobic

۰ Slow growth

۰ Grow in both acidic and basic condition

۰ Filamentous - Mycelia

Bacteria

۰ Smaller

۰ Prokaryotic

۰ Aerobic and Anaerobic

۰ Fast growth

۰ Prefer neutral media

TheOhioStateUniversity

slide3

CLASSIFICATION OF FUNGI

☞ Fungi kingdom (yeasts and molds)

  • Subkingdom: based on septation of mycelia
  • Phylum: based on ability to produce and type of sexual spores

TheOhioStateUniversity

slide4

UBIQUITOUS IN FOOD

- Spoilage

  • Toxicity
  • Fermented foods
  • Food additives & processing aids

TheOhioStateUniversity

slide5

FUNGI OF INTEREST

☞ Yeasts:

  • Saccharomyces spp.
  • Zygosaccaromyces spp.
  • Candida spp.

☞ Molds:

  • Rhizopus spp.
  • Asperigillus spp.
  • Penicillum spp.

TheOhioStateUniversity

slide6

BUDDING YEAST (Saccharomyces spp.)

- The Bakers’ and Brewer’s yeast

  • Most yeasts, including Saccharomyces reproduce by budding
  • does not ferment lactose
  • White or cream colonies
  • Typical yeasty odor

TheOhioStateUniversity

slide7

Rhizopus spp.

- Nonseptate, root-like structure

  • Umbrella-shaped columellae
  • Large sporangiospore with striated wall
  • Dark sporangia containing dark to pale spore

TheOhioStateUniversity

slide8

Penicillium spp.

- P. digitarum: yellow green conidia

  • P. italicum and P. expansum: blue-green conidia
  • P. camemberti: grey conidia

TheOhioStateUniversity

slide9

Aspergillus spp.

- Black, brownish black, purple brown conidiophore

  • Yellow to green conidia
  • Dark sclerotia
  • A. niger: black rot on fruits and vegetables

TheOhioStateUniversity

slide10

OBJECTIVES

☞ Enumeration of yeasts and molds

(difference between processed and fresh grapefruit juices)

☞ Importance of selective and differential media

☞ Compare and contrast fungi morphology macroscopically and microscopically

TheOhioStateUniversity

slide11

DEFINITION

  • ☞ Selective media
  • Allow microorganisms of interest to grow and have a selective advantage over otherwise competing organisms
  • Contain selective agents
  • ☞ Deferential media
  • Distinguish between two microorganisms based on a single or multiple biochemical properties
  • Contain differential agents

TheOhioStateUniversity

slide12

SELECTIVE MEDIA

  • ☞Acidified Potato Dextrose Agar (PDA)
  • Tartaric acid lowers pH to inhibit bacterial growth
  • Note: Some acid-tolerant bacteria can still grow leading to an over-estimate of fungi count

☞Antibiotic TSA (Not PCA)

- Chloramphenicol and chlortetracycline inhibit bacteria

TheOhioStateUniversity

slide13

MEDIA CONT’D

  • ☞Petrifilms
  • Selective and differential for yeasts and molds
  • Contain chlortetracycline and chloramphenicol
  • Indicator: bromo-chloro-indolylphosphate gives yeast a blue-green color
  • Yeasts: small and defined
  • Molds: larger and diffuse

TheOhioStateUniversity

slide14

LAB PERIOD 1

☞ Cut grapefruit in half and extract juice

  • Refrigerate (4 °C) it until used

☞ Reconstitute frozen concentrated grapefruit juice

  • Mix water (about three can) and one can of frozen concentrated grapefruit juice
  • - Refrigerate (4 °C) it until used.

TheOhioStateUniversity

slide15

LAB PERIOD 1

☞ Prepare media:

  • Add tartaric acid to the PDA
  • Add antibiotic solution to the TSA
  • Allow plates to dry 24-48 hours

TheOhioStateUniversity

slide16

LAB PERIOD 2

☞ Take 10 ml sample and Prepare 10-1 and 10-2 dilution of the sample using the 9 ml peptone blanks

  • ☞Spread plate dilutions in duplicate onto Acidified PDA (6) and antibiotic TSA (6)
  • ☞Transfer 1 ml of the dilutions 10-1 and 10-2 onto Petrifilms
  • Do not use undiluted sample because this produces artifacts
  • ☞Incubate at 25 °C for 5 days

TheOhioStateUniversity

slide17

LAB PERIOD 3

☞ Enumerate plates

  • ☞Pick 3 yeast colonies and examine different colony morphologies (macroscopically) and microscopically
  • ☞Place a drop of lactophenol cotton blue dye on a slide and place tape with mold onto surface – examine micro/macroscopically
  • Lactic acid: preserve fungal structures
  • Phenol: killing agent
  • ☞View demo microscope slides
  • ☞ Draw and record morphologies

TheOhioStateUniversity