CP 9 antimicrobial properties of plants

state 6 aseptic techniques

• wipe down surfaces with antibacterial cleaner before and after experiment

• use a bunsen burner in the work space so that convection currents draw microbes away from the culture

• flame the wire hoop before using it to transfer bacteria

• flame the neck of any bottles before suing them to prevent any bacteria entering the vessel

• keep all vessels containing bacteria open for the minimum amount of time

• close windows and doors to limit air currents

how is plant extract prepared

grind the selected plant sample into a paste then add a few cm3 of ethanol

how is the control of the practical set up

dip a filter paper disc in ethanol and place on the agar plate

why is bacteria incubated at 25 C

to prevent the growth of pathogens (harmful bacteria) which occurs at higher temperatures

how can you compare the effectiveness of different extracts applied to the same bacteria

measure the diameter and calculate the area of the zone of inhibition (clear zone) on the agar

what does the zone of inhibition indicate

it indicates the bacteria killed by the antibiotic the larger the zone the more effective the antimicrobial properties of the plant

state the hazards and precautions of this practical

naked flame : keep away from flammable materials tie hair up wear goggles

bacteria is a biohazard use disinfectant and wash hands dispose of bacteria safely

disinfectant is flammable keep away from naked flame

why should the lid not be completely taped to the petri dish

the allow oxygen to enter the petri dish preventing the growth of harmful anaerobic bacteria

why is the petri dish incubated upside down

to prevent condensation from forming on the lid and dripping down onto the agar

describe the graph that can be plotted from the results of this practical

a bar chart of zone of inhibition against plant extract