(ii) You set out to investigate the proportion of culturable bacteria in the soil of your local park that are resistant

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Ii You Set Out To Investigate The Proportion Of Culturable Bacteria In The Soil Of Your Local Park That Are Resistant 1 (56.73 KiB) Viewed 128 times

(ii) You set out to investigate the proportion of culturable bacteria in the soil of your local park that are resistant to the antibiotic tetracycline. You collect a soil sample. homogenise it, aseptically make up a set of serial dilutions and plate out 100 μl of each of these dilutions onto both nutrient agar, and nutrient agar containing tetracycline. The table below shows the results from the agar plates which had countable numbers of colonies. Soil sample Colony numbers on nutrient agar 1:8000 Colony numbers on nutrient agar with tetracycline 1:1000 dilution replicates dilution plate plate 12 35 Replicate 1 43 Replicate 2 Replicate 3 48 16 17 Using this data work out answers to the following (please show calculations) a) What is the average CFU per mL for bacteria in this soil on nutrient agar? b) What is the average CFU per mL for bacteria in this soil on nutrient agar with tetracycline? c) What percentage of culturable bacteria in the sample show tetracycline resistance? What current practices are potentially contributing to increased rates of antibiotic resistant genes and bacteria in soils? (6 marks)