Influence of abaR gene knockout on growth metabolism and biofilm formation of Acinetobacter baumannii / 中华烧伤杂志

ABSTRACT

Objective@#To investigate the influence of abaR gene knockout on growth metabolism and biofilm formation of Acinetobacter baumannii.@*Methods@#The abaR gene was knocked out from Acinetobacter baumannii standard strain ATCC 17978 (wild strain) by homologous recombination method, and then the ATCC 17978 abaR knockout strain (ATCC 17978/ΔabaR Kn) was obtained and verified by polymerase chain reaction (PCR) electrophoresis and sequencing. The growth curves of Acinetobacter baumannii wild strain and Acinetobacter baumannii 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, t test, and least-significant difference test.@*Results@#(1) The length of PCR product of target fragment ΔabaR Kn was 3 029 bp. The abaR 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 abaR gene was successfully knocked out. (2) At CH 2, 3, and 4, the absorbance values of Acinetobacter baumannii wild strain were slightly higher than those of the knockout strain. The absorbance values of Acinetobacter baumannii wild strain and knockout strain were similar from CH 5 to 18. (3) At CH 8 and 24, the biofilm formation ability of Acinetobacter baumannii 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, t=2.209, 1.167, P>0.05). At CH 48, the biofilm formation ability of Acinetobacter baumannii wild strains (1.157±0.259) was significantly stronger than that of Acinetobacter baumannii knockout strains (0.576±0.026, t=3.865, P<0.05). The biofilm formation ability of Acinetobacter baumannii wild strains at CH 48 was significantly stronger than that at CH 8 and 24 (P<0.05). The biofilm formation ability of Acinetobacter baumannii knockout strains at CH 24 was significantly weaker than that at CH 8 and 48 (P<0.05).@*Conclusions@#The abaR gene of Acinetobacter baumannii ATCC 17978 can be successfully knocked out by homologous recombination to obtain its knockout strain ATCC 17978/ΔabaR Kn. The abaR gene does not affect the growth and metabolism of Acinetobacter baumanniibut can weaken its biofilm formation ability.