Death death of cells due to lack of nutrients and

Info icon This preview shows pages 4–5. Sign up to view the full content.

Death- Death of cells due to lack of nutrients and large amounts of toxins 3. Spectrophotometer a. Used to measure Optical Density b. Measures quat the turbidity of broth i. When light is passed through the broth it is either transmitted (passed through), absorbed (by the solution), reflected (negligible), fluoresced (neg) or scattered (neg) 4. Std Plate Count a. Indirect means of measuring cell density (cells/mm) b. Optimal cell density is around 30-300 countable colonies c. Serial Dilutions
Image of page 4

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

i. Dilution Factor (DF) is a tracking system of the original sample present within the dilutions 1. Diluent (h2o or saline) is solvent ii. D= D1/V2 1. V1 vol of inoculate( broth) 2. V2 is total vol (inoculate+diluent) 5. Water Microbiology a. The concern is not the amount of bacteria present, but the type of bacteria present . i. Free of intestinal pathogens b. Fecal Coliforms in recreation contact: <200/dl or 2/ml c. Non contact recreation: <2000/dl or 20/ml d. Test for indicators, not pathogens i. E. coli and Streptococcus faecalis are good sewage indicators. Do not survive in water for a long time, and do not form spores, easy to id e. E Coli: non spore forming rod, and a coliform: facultative anaerobe, ferments lactose to prod gas and is g- f. S faecalis: g+ coccus, and enterococcus g. ID COLIFORMS: i. Presumptive Test - series of 9 or 12 tubes of lactose broth are inoculated with measured amounts of water. If theres gas, + for coliforms. Also detect MPN of coliforms present per 100 ml of water ii. Confirmed test - plates of EMB agar or Endo agar are inoculated from positive (gas- producing) tubes to see if they are g- (inhibits g+). 1. Agar coliforms = small colonies with dark centers 2. Endo agar coliforms – red colonies iii. Completed test - determine if the isolate from the agar plates truly matches our definition of a coliform. 1. Media is agar slant and durham tube of lactose broth. 2. If gas produced in lactose tube, and slide is g- non spore forming, then yes for coliform h. Of the two, E. coli is the better sewage indicator since E. aerogenes can be of non-sewage origin. i. To differentiate these two species, one must perform the IMVIC tests.
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.
  • Summer '08
  • FRYE
  • Bacteria, Growth medium, i., Mitis Salivarius Agar, Endo agar coliforms

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern