What are is the growth rate of bacteria measured using a batch culture that has been incubated for ~16hrs?
465621
Usually at this point the culture is well established, and dilutions will then be made and the optical density of the dilutions can be figured out, which determines the growth rate.  After 24 hours cells start to die off b/c of lack of nutrients.  After 48 hours, the culture will still be viable but not the best source of robust growth.  16 hours is pretty arbitrary I guess, but it usually represents an overnight incubation, ie incubate at 5pm, come back at 9am.
520742
The activity of an enzyme is tested by measuring how quickly it degrades the substrate or how quickly product is formed in an enzyme-catalyzed reaction.  This can be measured using spectrophotometry.\n\nHowever, you cannot compare these activities in samples with different protein concetrations because the increased enzyme activity may only be due to the fact that there are more enzymes contained in the sample.  Therefore, you divide the activity by the total amount of protein in the sample.  This way you can compare the activities of different samples and get an idea of how well the enzyme is functioning in different environments.\n\nAs for the calculations, just asking me to do them is giving me nightmares about my biochemsitry course I just completed.  If you already have the activity, you divide it by the total mass of protein present in the sample to get the specific activity.  If you are doing a purification procedure, the more you purify the sample, the less protein will be present and as long as the enzyme of interest remains in the assay samples the specific activity should go up.
196649
Several ways to do this. The first that occurs to me is to have the mammalian cell culture in a sealed chamber and measure the gases via IR spectroscopy in the chamber. The loss of oxygen in the gas of the chamber would be the uptake. Such methods are quite sensitive.
261456
Your culture is transparent to longer wavelengths, the same as our atmosphere shows the red rays, the last ones for a setting sun.\n\n600nm probably picks up your bacteria most efficiently, based on their size.\n\nWhy don't you run some experimental data off using shorter and longer wavelengths?\n\nAlso, compare the actual bacteria sizes to the wavelength.
149491
This is a "rule of thumb" that is the average of a lot of kinetic data.  To blindly apply it is unwise, but as a zero order estimate, it should work OK.  Detailed measurements must be done on your system of interest to find out true kinetic parameters and their sensitivity.
159306
Preenrichment- for non fat dry milk and dry whole milk, weigh 100g of product and transfer to 1L distilled water containing 2ml of 1%aqueous brilliant green dye.Incubate at 35C for 24 +/- 2hrs. Enrichment- transfer 1ml of pre enrichd smple to 10 ml selenite cystine broth and tetrathionate broth respectively incubate at 35C for 24 +/- 2hrs.streak from enrichment media to the ff diff media: brilliant green, salmonella-shigella and bismusth sulfite incubate at 35C fo 24 +/- 2hrs.\nappearance of typical colonies:\nBGA- colorless, pink to fuchsia, translucent to opaque with surrounding medium pink to red.\nSSA- uncolored to pale pink, opaque, transparent or translucent; some produce black centered colonies.\nBSA- brown black sometimes with metallic sheen.\nsubject for further identification using  TSI agar for confirmation.streak the slant and stabb the butt. salmonella positive TSI cultures have alkaline red slants and acid (yellow) butt with or without H2S (blackening of agar) =)
566223
There are several ways to do it.. \n\nYou can perform an ELISA (Enzyme linked immunosorbant assay) this technique involves the use of antibodies specific for the cytokine you wish to measure and then a secondary antibody to bind to the antibody against the cytokine which is tagged with an enzyme that can change colour when a certain chemical is added allowing the whole reaction to be quantified and measure the amount of cytokine being produced.\n\nAnother method to use is reverse transcriptase PCR - this measures the amount of mRNA made of the cytokine of interest.. However controversy exists over this method as it is not known if the amount of mRNA present is truly indicative of the amount of protein made.\n\nHope this helps..\n\nKatie
774925
Boil ¼ cup of water. Add one teaspoon of gelatin and one teaspoon of\nsugar. Stir for one minute until everything is dissolved.\n2. Cool the solution for ten minutes.\n3. Fill a petri dish to a little below the top edge.\n4. Close the petri dish by putting on the cover immediately. Let the\ncovered petri dish stand for at least four hours. Don’t touch the\ngrowth medium or you’ll add your own germs!\nThis recipe will fill two, small petri dishes. If you and your class plan to fill\nmore petri dishes, make more germ food by increasing the amount of your\ningredients proportionally.\n*Adapted from Gross But True Germs by Luann Colombo. See details in bibliography. If you don’t\nhave the materials needed for the experiment, you can purchase Ms. Colombo’s book, which includes\nall the supplies needed to conduct the experiment.
255920
The factor of time dilation depends on the square root of (1-v^2/c^2). Taking the speed of light as 1 and the speed of the bacteria as .9950, the time dilation factor is\n\nsqrt(1 - .9950^2) = just slightly less than .1\n\nThus, time slows for the bacteria and they think they are in space for 100 days, even though 1000 days pass on earth. They will double 5 times, once every one of "their" 20 days, to 4, 8, 16, 32, and finally 64 upon their return to earth.
628104
Nutrient agar is a basic non-selective medium used for growing bacteria generally.\n\nmeat extract 3g\npeptone (bactopeptone) 10g\nNaCl 5g\nagar 15g\ndistilled water 1L\n\nSterilization by autoclaving 121 °C, 20 min.
21641
yogurt with active live cultures,read the label
784116
When I was in Microbiology class, I was taught to stab the agar after streaking, to form sort of an Anaerobic chamber to look for Anaerobic hemolysis/growth. To this very day if and when I am working in microbiology, I still do a 4 way streak, and stab at the end. \nWhen streaking a BAP confirmation plate for tests such as a Quick Strep test, that stab can be of definite help.
897445
usually for gram stain, if the color is blue, the organism is gram positive and if it's pink, the organism is gram negative since the cell wall structure wouldn't be able to sustain the washing; however, the result would only be valid for a short amount of time....and since the culture was left in the incubator for a longer period of time, some of the same microorganisms have lost the ability to retain the stain and therefore the color changed from intense blue to pink...the best thing to do would be to redo the gram stain and to make sure that the culture does not stay in the incubator for too long
233635
not long, as you may know yogurt is bacteria.
263670
Hmmm... judging by your interest in cleaning products and dishwashing detergents, I'm guessing you're in that industry or just a student looking for some answers for a project.\n\n-Insufficient data - \nAre you referring to dishwater in a more sterile kitchen or a dirty restaurant?  Is the piping clean or are we talking rusty piping?  Filtered water or non filtered water? Hmmm... so, at STP you want to figure out this. \n\nHere's what you would need.  First figure out the type of microbes that would typically exist in your sink.  Or if you don't have one, get some kind of bacteria.  Take the whole thing, perform your experiment.  Take some water samples.  Finally, send the water samples to a lab immediately for a count.  You could get a concentration of microbes per given volume.  My advice -- it's all I can do.
476381
Actually, your teacher is wrong.  It all depends on the growth phase of the bacterial culture.   There are 3 phases in the growth of a bacterial culture; the lag phase, the log phase, and the stationary phase.  The lag phase is exactly what it describes...the bacteria divide veeeeerrrryyy slowly.  In simple terms, this is mainly due to low amounts of certain "growth signals".  It usually takes bacteria several hours to get out of lag phase and into log phase.  \n\nLog phase is the stage where the bacteria are dividing at a constant rate.  This is when you're going to take measurements for the growth rate.  Say, for example, that your cells have a doubling time of 1hr.  So if your beginning OD is 0.8 your end OD after an hour would be 1.6.  In this case B is twice b.  However using the same example, if we grow for 2 hours instead of 1, you've gone thorugh 2 doubling times and the final OD would be 3.2 verses 0.8 (B is 4x b).  So the relation between b and B is strictly dependant on the time (which is why "t" is a component of the equation) and growth rate of the cells.\n\nThe final phase of bacterial growth is the stationary phase.  This is where the number of bacteria increases to such a high density that further division is inhibited (by physical limitations such as nutrients, pH, cell/cell inhibition, etc) and the growth substatially slows.\n\nI hope this clearly answers your question.
84488
This deals with antibiotic susceptibility testing on (usually Mueller-Hinton) agar plates.  \nFirst you coat the surface of the plate with a bacterial suspension, then you place a disc with whatever antibiotic you're using on the surface of the plate.  After you incubate the plate for about 18 to 24 hours, you will see a zone of inhibition around the disc if the bacteria are killed, or inhibited, by the antibiotic.  This is an area of no bacterial growth.  The sizes of the zones vary depending on the concentration of the antibiotic in the disc, the depth of the agar, the susceptibility of the bacteria, and the concentration of the origional bacterial suspension, etc. . .\n\nHope this helps!