MICROBIOLOGICAL ENGINEERING - QUESTION 28.1 : In the calculation of the growth of bacteria, colony forming unit (CFU) in serial dilution is used. In a laboratory, viable count assay is used to estimate CFU. Formula applied is CFU / mL = (number of colonies x dilution) / (amount plated, in unit mL). Acceptable plate count is either between 20 and 200 or between 30 and 300 according to 2 different references. A wastewater sample of 200 ml is added to and mixed with 1.8 L of sterile water. Another 200 ml of the mixture is added to and mixed with 1.8 L of sterile water. (a) Calculate the dilution of first mixture and the dilution of the second mixture. (b) 100 microlitres of wastewater samples from the first mixture and the second mixture are placed separately on 2 different alga plates. The first plate has 250 colonies and the second plate has 23 colonies. Calculate the average CFU / mL.
- 1 Answers
- 1543 Views
- I also Faced
- E-Mail Answers
MICROBIOLOGICAL ENGINEERING - ANSWER 28.1 : (a) Dilution = (final volume of mixture) / (initial volume of mixture). First dilution = ( 0.2 + 1.8 ) L / (0.2 L) = 10. Second dilution = first dilution x ( 0.2 + 1.8 ) L / (0.2 L) = 10 x 10 = 100. (b) 100 microlitres = 100 microlitres x 1 mL / (1000 microlitres) = 0.1 mL. CFU / mL = (number of colonies x dilution) / (amount plated, in unit mL). In the first plate, CFU / mL = 250 x 10 / 0.1 = 25000. In the second plate, CFU / mL = 23 x 100 / 0.1 = 23000. Average CFU / mL = (first plated value + second plated value) / 2 = (25000 + 23000) / 2 = 24000. The answer is given by Kang Chuen Tat; PO Box 6263, Dandenong, Victoria VIC 3175, Australia; SMS +61405421706; chuentat@hotmail.com; http://kangchuentat.wordpress.com.
| Is This Answer Correct ? | 0 Yes | 0 No |
Question 8 - A local utility burns coal having the following composition on a dry basis : Carbon (C) 83.05 %, hydrogen (H) 4.45 %, oxygen (O) 3.36 %, nitrogen (N) 1.08 %, sulfur (S) 0.7 % and ash 7.36 %. Calculate the ash free composition of the coal with reference to C, H, O, N and S.
What type of heat exchangers are most commonly used for a large-scale plant-cooling loop using seawater as the utility?
What are the effects of oils on the properties of Polyolefins?
why PH scale range is 14? why it is not less or not greater than 14? solution of HCl or hydrogen containing liquid has a PH. but if the solution is KMnO4 here not hydrogen power does it PH? explain plz....
i m a frsh chemical engineer now i m confuse to attend the interview so anybody pls send model question papers to this christ_vivek33@yahoo.com
What is the most common carrier gas used in pneumatic conveying?
What are pcbs?
what is the speed of a rotary drier
What does the catalytic converter on an automobile really do?
when liquid stored in spherical vessel,equilibrium shift towards liquid.what is the benefit of it?
What are the strategies acquired to cure tube vibration and exchangers in a shell?
Explain some good strategies for curing tube vibration in shell and tube exchangers?
-
Civil Engineering (5085) - Mechanical Engineering (4451)
- Electrical Engineering (16632)
- Electronics Communications (3918)
- Chemical Engineering (1095)
- Aeronautical Engineering (239)
- Bio Engineering (96)
- Metallurgy (361)
- Industrial Engineering (259)
- Instrumentation (3014)
- Automobile Engineering (332)
- Mechatronics Engineering (97)
- Marine Engineering (124)
- Power Plant Engineering (172)
- Textile Engineering (575)
- Production Engineering (25)
- Satellite Systems Engineering (106)
- Engineering AllOther (1379)
