唐菖蒲伯克霍尔德菌椰毒致病变种污染调查及其生长与产毒特性分析

Contamination of Burkholderia gladioli pathovar cocovenenans in Retail Foods and Its Growth and Toxicity Characteristics

唐菖蒲伯克霍尔德菌椰毒致病种(Burkholderia gladioli pathovar cocovenenans,BGC)是迄今我国发现的发病率和死亡率最高的食源性致病菌。为调查广州市市售湿米面制品、银耳及木耳中BGC的污染状况,同时掌握在不同培养条件下BGC的生长与产毒规律,依据GB 4789.29-2020对100份食品样品进行定性分析;通过测定BGC菌株在各培养条件下菌液的OD600值和毒素含量,分析了不同的温度、时间、pH及NaCl浓度下BGC的生长状况与产毒能力。结果表明,100份食品样品中共检出1份(湿木耳)BGC阳性样品,污染率为1%(1/100);BGC的生长与产毒受培养基的影响较大,碱性(pH值为9.5~10.5)与一定渗透压(NaCl质量浓度为0.02~0.04 g/mL)环境下,BGC在马铃薯葡萄糖水中能生长,而在脑心浸液肉汤中几乎不生长,BGC在马铃薯半固体琼脂中的产毒量(231.24μg/mL)远大于BHI半固体琼脂和LB半固体琼脂;BGC适宜生长和产毒的温度为20~37℃、适宜pH值为4~8.5,其中最适生长温度与pH值分别为37℃、6.0,最佳产毒温度与pH值为30℃、7.0;BGC在低温(4~15℃)下仍能存活,且有少量的毒素产生(2.11μg/mL);当NaCl质量浓度为0.005 g/mL时,产毒量从未添加前的139.80降至52.27μg/mL,达到0.04 g/mL时,产毒为0。结果提示,广州市市售木耳中存在BGC污染的风险,在食品加工或贮存过程中添加一定浓度的NaCl可减少由BGC引起的食物中毒。

Burkholderia gladioli pathovar cocovenenans(BGC)is a food-borne pathogen with the highest morbidity and mortality found in China.Outbreaks of severe,BGC-caused food-poisoning have been reported every year in Guangdong Province from 2018 to 2020.The prevalence of BGC in commercial wet rice flour products,white tremella,and agaric in Guangzhou and growth and toxin production characteristics of the pathogen under various conditions were determined.One hundred food samples were subjected to qualitative analysis for BGC using the national food safety standard food microbiological examination(GB 4789.29-2020).By measuring the OD600 values and the contents of toxins under different culture conditions,the growth and the toxin-producing abilities of BGC under different incubation temperatures and durations,pH values,and NaCl concentrations were evaluated.Of the 100 food samples,one sample(in agaric)tested positive for BGC.The growth and toxin production of BGC were greatly affected by the culture medium.BGC grew in potato dextrose,but hardly grew in brain heart infusion broth in an alkaline environment(pH value 9.5~10.5)and at NaCl concentrations of 0.02~0.04 g/mL.The toxin production of BGC in potato glucose semisolid agar(231.24μg/mL)was much higher than that in BHI and LB semisolid agar(38.84μg/mL).The growth and toxin production temperature and pH value suitable for growth of BGC were 20~37℃and 4~8.5;optimal growth temperature and pH value were 37℃and 6.0;and the optimal toxin production temperature and pH value were 30℃and 7.0,respectively.BGC survived and produced toxins(2.11μg/mL)at low temperatures(4~15℃).The toxin production of BGC was obviously inhibited at high NaCl concentrations.When the NaCl concentration was 0.005 g/mL,the toxin production decreased from 139.80μg/mL to 52.27μg/mL;at 0.04 g/mL,no toxins were produced.There is a risk of BGC contamination in agaric in Guangzhou.BGC-caused food-poisoning outbreaks can be reduced by adding NaCl during food processing or storage.