Question

1. How is Chitosan hypothesized to decrease number of bacterial colonies?

2. Through what phenomenon does vertexing and sonication removes bacteria from a suture?

3. What methods tare used to evaluate bacterial concentration in a solution?

Answer 1

A) chitosan exhibited antimicrobial activity. Several hypotheses have been proposed based on its cationic nature. Low-molecular-weight chitosan can penetrate bacterial cell walls ,bind with DNA and inhibit DNA transcription and mRNA synthesis while high molecular weight chitosan can bind to the negatively charged component of the bacteria cell wall. It forms an impermeable layer around the cell, changes cell permeability and blocks transport into the cell.The hydrophilicity and negative charge on cell surface were higher on gram-negative bacterial cell walls than those of gram-positive bacteria .Thus the gram-negative bacteria showed a stronger interaction with chitosan, which resulted in strong antibacterial activity against them .The amount of chitosan binding to the bacterial cell wall was dependent on the environmental pH value , molecular weight and degree of acetylation of chitosan .Low environmental pH increases the positive charge in the chitosan polymer , which favors binding to the bacterial cell wall .A reduction in the molecular weight of chitosan increases the antibacterial activity of chitosan towards Gram-negative bacteria and reduces the activity on Gram-positive bacteria. Chitosan has a wide spectrum of activity and high killing rate against Gram-positive and Gram-negative bacteria.

c) spectrophotometry