Influence of abaR gene knockout on growth metabolism and biofilm formation of Acinetobacter baumannii

Objective To investigate the influence of

gene knockout on growth metabolism and biofilm formation of

. Methods The

gene was knocked out from

standard strain ATCC 17978 (wild strain) by homologous recombination method, and then the ATCC 17978

knockout strain (ATCC 17978/ΔabaR: : Kn) was obtained and verified by polymerase chain reaction (PCR) electrophoresis and sequencing. The growth curves of

wild strain and

knockout strain were determined by microplate reader within cultivation hour (CH) 18, and the biofilm formation ability was measured by crystal violet staining at CH 8, 24, and 48, respectively. The sample number at each time point was 3.The results were denoted as absorbance value. Data were processed with analysis of variance of factorial design, one-way analysis of variance,

test, and least-significant difference test. Results (1) The length of PCR product of target fragment ΔabaR: : Kn was 3 029 bp. The

gene was knocked out to obtain the knockout strain ATCC 17978/ΔabaR: : Kn. The length of PCR product of the knockout strain was 3 300 bp. The

gene was successfully knocked out. (2) At CH 2, 3, and 4, the absorbance values of

wild strain were slightly higher than those of the knockout strain. The absorbance values of

wild strain and knockout strain were similar from CH 5 to 18. (3) At CH 8 and 24, the biofilm formation ability of

wild strains (0.644±0.066, 0.574±0.184) was similar to that of knockout strains (0.559±0.008, 0.394±0.030,

=2.209, 1.167,

>0.05). At CH 48, the biofilm formation ability of

wild strains (1.157±0.259) was significantly stronger than that of

knockout strains (0.576±0.026,

=3.865,

<0.05). The biofilm formation ability of

wild strains at CH 48 was significantly stronger than that at CH 8 and 24 (

<0.05). The biofilm formation ability of

knockout strains at CH 24 was significantly weaker than that at CH 8 and 48 (

<0.05). Conclusions The

gene of

ATCC 17978 can be successfully knocked out by homologous recombination to obtain its knockout strain ATCC 17978/ΔabaR: : Kn. The

gene does not affect the growth and metabolism of

but can weaken its biofilm formation ability.