Synthesis and evaluation of antibacterial activity of quaternized biopolymer from Klebsiella terrigena




Microbial exopolymer with antimicrobial properties, in particular, has gathered considerable interest due to their enormous scope of modification and wide gamut of application. The purpose of present study was to evaluate the antibacterial spectrum of a chemically modified biopolymeric flocculant produced by Klebsiella terrigena.

Methods and Results

N,N,N trimethyl biopolymer (TMB) was synthesized using dimethyl sulfate as methylating agent and was characterized by nuclear magnetic resonance and mass spectroscopic analysis, which confirmed the presence of quaternary ammonium groups on the TMB structure. The antibacterial activity of TMB was investigated against three selected bacterial pathogens viz. Aeromonas hydrophila ATCC 35654, Listeria monocytogenes ATCC 19111 and Escherichia coli O157:H7 ATCC 32150. An inactivation of 3 log CFU ml−1 of all pathogens was noticed for TMB when compared to native polymer over a short contact time (60 min) and low dosage (60–80 μg ml−1) at ambient temperature. A marked increase in glucose level, protein content and lactate dehydrogenase (LDH) activity was observed concurrently in the cell supernatant suggesting damage of the cell membranes to be a possible reason for inactivation.


The quaternization of amino rich biopolymer isolated from a bacterium led to a water-soluble bioactive agent with enhanced inhibitive capability against all the selected bacterial pathogens.

Significance and Impact of Study

The results of this study suggest a potential application of TMB as an effective disinfectant in water treatment.