Date of Award

Spring 5-9-2025

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Animal Sciences

First Committee Advisor

Juan Romero

Second Committee Member

Anne Lichtenwalner

Third Committee Member

Zhengxin Ma

Abstract

A series of experiments were conducted to determine the minimum inhibitory concentration (Alzagameem et al.) and minimum bactericidal concentration (MBC) of a set of technical lignins that could be used as conditioners in lactating cattle beddings. Mueller Hinton broth was modified to pH 6 and used in macro dilution to determine the antimicrobial activity strains of Staphylococcus chromogenes (KCJ4610), Streptococcus uberis (BAA-854), Klebsiella pneumoniae (KCJ4749), Escherichia coli (PSU-10.0371), and Pseudomonas aeruginosa (KCJ4633) isolated from mastitic cows. Technical lignin treatments assessed were; sodium lignosulfonate (Yang et al.), washed kraft lignin (WKL), alkali kraft lignin (AKL), and magnesium lignosulfonate (MgL). MIC and MBC analysis were carried out in duplicate in each of three independent runs. The NaL inhibited both S. chromogenes and S. uberis (gram positive) at a lower dose than P. aeruginosa, E. coli, and K. Pneumoniae (gram negative). A similar trend was observed for bactericidal activity, except for P. aeruginosa, which could not be killed by any of the lignins tested. MgL was less inhibitory against P. aureginosa and E. coli, relative to the other bacteria, but it was the most effective lignin against E. coli. The MgL killing activity was the highest against S. chromogenes and S. uberis, relative to the other bacteria. The AKL was more effective at inhibiting and killing S. chromogenes and S. uberis, relative to other bacteria, which were impervious to its activity. WKL antibacterial effects were mostly restricted to S. chromogenes, in our study. Overall, NaL had the most rounded and effective antibacterial activity, followed by MgL and AKL.

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