Biology Lab Report On The Effects Of Different Bio-toxins On E. Coli

Introduction

This experiment investigates the rapidity with which Escherichia Coli can part complete resistance under strong selection in the lab. Water was chosen as a control, and triclosan, household chlorine/bleach, as well as penicillin were compared amongst each new(prenominal). Biocides puddle been co-ordinated into a wide variety of consumer products because it is thought to protect macrocosm from potentially harmful microbes including bacteria and fungi. If a biocide acts in a general way like an antiseptic, then it is unlikely that every single microbe would evolve to be resistant to that nucleus; this line of reasoning was initially used to justify widespread use of triclosan as being beneficial without creating the danger of selecting for triclosan-resistance among potentially harmful microbes.

However, some researchers take on shown that triclosan acts on bacteria in single specific way - by inhibiting one of the highly conserved enzymes (enoyl-ACP reductase, or FabI) of bacterial fatty-acid biosynthesis. Further, they have found that, several key pathogenic bacteria do not possess FabI, entirely rather have a unique triclosan-resistant flavoprotein, FabK, that can also catalyse this reaction in Streptococcus pneumoniae. (Heath + Rock, 2000). Mutations in the FabI gene have been discover in E. coli; utilisation of FabK rather than FabI has been observed in Pseudomonas.



Some bacteria have also been shown to have developed sensitivity to triclosan in their two-fold antibiotic resistance (mar) operon. This activates a pump in the bacterial cell wall that expels a host of unwanted chemicals, including other (possibly still effective) biocides (Clarke, 2001). A final method of triclosan resistance that has been observed is glycosylation of triclosan molecules (Reither, 2002).

The hypothesis is that the E. coli will form a resistance to triclosan and penicillin relatively quickly, and also to chlorine/bleach but over a longer period of...

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