4b血清型菌株在不同温度下,在哈密瓜表皮和果肉上比1/2a血清型和4b-v1血清型菌株表现出适应性优势。

serotype 4b strains demonstrate a fitness advantage over strains of serotypes 1/2a and 4b-v1 on cantaloupe rind and flesh at different temperatures.

作者信息

Gorski Lisa, Aviles Noriega Ashley, Carter Michelle Qiu

机构信息

USDA, Agricultural Research Service, Western Regional Research Center, Produce Safety and Microbiology Unit, Albany, California, USA.

出版信息

Microbiol Spectr. 2025 Sep 2;13(9):e0125225. doi: 10.1128/spectrum.01252-25. Epub 2025 Aug 7.

Abstract

is a foodborne pathogen implicated in several produce-related outbreaks. In nature, it is saprophytic and is isolated from agricultural areas and surface waters. The ability of the pathogen to grow at cold temperatures results in population growth when contaminated foods are stored in the refrigerator. Most outbreaks are caused by serotypes 1/2a and 4b. In the last decade, several produce-related outbreaks have been caused by an atypical serotype 4b subtype termed 4b-v1, specifically strains of sequence type (ST) 382. ST382 strains are overrepresented in environmental isolates. This study asked if strains of ST382 displayed better fitness on produce by growing to higher levels on cantaloupe surfaces when inoculated as strain mixtures. Strains of serotypes 1/2a, 4b, and 4b-v1 were co-inoculated onto cantaloupe rinds and flesh and incubated for 24 h at 25°C or for 7 days at 4°C. After rinsing, 30 resulting colonies were screened for serotype. Serotype 4b strains demonstrated significantly better fitness on cantaloupe rind than either serotype 1/2a or 4b-v1 strains. On cantaloupe flesh, serotypes 4b and 4b-v1 strains were statistically similar, and serotype 4b was more fit than serotype 1/2a. Serotype 4b colonies represented approximately 50% of the colonies recovered from rind and 40% of the colonies recovered from flesh. Incubation temperature was not a factor. While all the strains could grow on both cantaloupe surfaces, the data indicate that strains of ST382 did not have a fitness advantage on cantaloupe.IMPORTANCEMost outbreaks are caused by serotypes 4b and 1/2a. An atypical variant of serotype 4b, 4b-v1, specifically sequence type (ST) 382, caused three nationwide produce-related outbreaks in the last decade. To address the fitness of ST382 on produce, these strains were inoculated in mixtures including serotypes 1/2a and 4b onto cantaloupe rinds and flesh and incubated at 25°C and 4°C. Fitness was determined by measuring the percentage recovery of the individual serotypes in the mixed population recovered from cantaloupe surfaces. Serotype 4b strains were recovered consistently at higher levels than both serotypes 1/2a and 4b-v1 strains from cantaloupe rind. On cantaloupe flesh, serotypes 4b and 4b-v1 were statistically equivalent, but serotype 4b had the advantage over serotype 1/2a strains. While all the strains can reproduce on the cantaloupe surfaces, ST382 was not more fit on the cantaloupe. Furthermore, serotype 4b strains had a fitness advantage in mixed populations on cantaloupe.

摘要

是一种与多种农产品相关疫情爆发有关的食源性病原体。在自然界中,它是腐生的,可从农业区域和地表水中分离出来。该病原体在低温下生长的能力导致受污染食品在冰箱中储存时种群数量增加。大多数疫情爆发是由血清型1/2a和4b引起的。在过去十年中,几起与农产品相关的疫情爆发是由一种非典型血清型4b亚型(称为4b-v1)引起的,特别是序列类型(ST)382的菌株。ST382菌株在环境分离物中占比过高。本研究探讨了ST382菌株作为菌株混合物接种时,在哈密瓜表面生长到更高水平,是否表明其在农产品上具有更好的适应性。将血清型1/2a、4b和4b-v1的菌株共同接种到哈密瓜皮和果肉上,并在25°C下孵育24小时或在4°C下孵育7天。冲洗后,对产生的30个菌落进行血清型筛选。血清型4b菌株在哈密瓜皮上的适应性明显优于血清型1/2a或4b-v1菌株。在哈密瓜果肉上,血清型4b和4b-v1菌株在统计学上相似,且血清型4b比血清型1/2a更具适应性。血清型4b菌落约占从瓜皮回收菌落的50%,占从果肉回收菌落的40%。孵育温度不是一个因素。虽然所有菌株都能在两种哈密瓜表面生长,但数据表明ST382菌株在哈密瓜上没有适应性优势。

重要性

大多数疫情爆发是由血清型4b和1/2a引起的。血清型4b的一种非典型变体4b-v1,特别是序列类型(ST)382在过去十年中引发了三起全国性的与农产品相关的疫情爆发。为了研究ST382在农产品上的适应性,将这些菌株与血清型1/2a和4b混合接种到哈密瓜皮和果肉上,并在25°C和4°C下孵育。通过测量从哈密瓜表面回收的混合群体中各血清型的回收率来确定适应性。从哈密瓜皮中回收的血清型4b菌株的水平始终高于血清型1/2a和4b-v1菌株。在哈密瓜果肉上,血清型4b和4b-v1在统计学上相当,但血清型4b比血清型1/2a菌株具有优势。虽然所有菌株都能在哈密瓜表面繁殖,但ST382在哈密瓜上并没有更强的适应性。此外,血清型4b菌株在哈密瓜的混合群体中具有适应性优势。

本文引用的文献

[8]
ALB65 Inhibits the Growth of on Cantaloupe Melons.

Appl Environ Microbiol. 2020-12-17

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