Abstract：
Alicyclobacillus spp. is the cause of great concern for the food industry due to their spores\' resistance (thermal and chemical) and the spoilage potential of some species. Despite this, not all Alicyclobacillus strains can spoil fruit juices. Thus, this study aimed to identify Alicyclobacillus spp. strains isolated from fruit-based products produced in Argentina, Brazil, and Italy by DNA sequencing. All Alicyclobacillus isolates were tested for guaiacol production by the peroxidase method. Positive strains for guaiacol production were individually inoculated at concentration of 103 CFU/mL in 10 mL of orange (pH 3.90) and apple (pH 3.50) juices adjusted to 11°Brix, following incubation at 45 °C for at least 5 days to induce the production of the following spoilage compounds: Guaiacol, 2,6-dichlorophenol (2,6-DCP) and 2,6-dibromophenol (2,6-DBP). The techniques of micro-solid phase extraction by headspace (HS-SPME) and gas-chromatography with mass spectrometry (GC-MS) were used to identify and quantify the spoilage compounds. All GC-MS data was analyzed by principal component analysis (PCA). The effects of different thermal shock conditions on the recovery of Alicyclobacillus spores inoculated in orange and apple juice (11°Brix) were also tested. A total of 484 strains were isolated from 48 brands, and the species A. acidocaldarius and A. acidoterrestris were the most found among all samples analyzed. In some samples from Argentina, the species A. vulcanalis and A. mali were also identified. The incidence of these two main species of Alicyclobacillus in this study was mainly in products from pear (n = 108; 22.3 %), peach (n = 99; 20.5 %), apple (n = 86; 17.8 %), and tomato (n = 63; 13 %). The results indicated that from the total isolates from Argentina (n = 414), Brazil (n = 54) and Italy (n = 16) were able to produce guaiacol: 107 (25.8 %), 33 (61.1 %) and 13 (81.2 %) isolates from each country, respectively. The PCA score plot indicated that the Argentina and Brazil isolates correlate with higher production of guaiacol and 2,6-DCP/2,6-DBP, respectively. Heatmaps of cell survival after heat shock demonstrated that strains with different levels of guaiacol production present different resistances according to spoilage ability. None of the Alicyclobacillus isolates survived heat shocks at 120 °C for 3 min. This work provides insights into the incidence, spoilage potential, and thermal shock resistance of Alicyclobacillus strains isolated from fruit-based products.
摘要：
脂环杆菌。由于它们的孢子抗性（热和化学）和某些物种的腐败潜力，引起了食品工业的极大关注。尽管如此,并非所有的脂环杆菌菌株都能破坏果汁。因此，本研究旨在鉴定脂环杆菌。从阿根廷生产的水果产品中分离出的菌株，巴西,和意大利的DNA测序。通过过氧化物酶方法测试了所有脂环杆菌分离株的愈创木酚生产。将愈创木酚生产的阳性菌株以103CFU/mL的浓度分别接种在调节至11°白利糖度的10mL橙汁（pH3.90）和苹果汁（pH3.50）中，在45°C下孵育至少5天以诱导以下腐败化合物的产生：愈创木酚，2,6-二氯苯酚(2,6-DCP)和2,6-二溴苯酚(2,6-DBP)。通过顶空微固相萃取（HS-SPME）和气相色谱-质谱（GC-MS）技术用于鉴定和定量腐败化合物。所有GC-MS数据通过主成分分析(PCA)进行分析。还测试了不同热冲击条件对接种在橙汁和苹果汁（11°白利糖度）中的脂环菌孢子回收率的影响。从48个品牌中分离出484株，在所有分析的样品中，发现的最多的物种是A.acidocaldarius和A.acidoterrestriris。在阿根廷的一些样本中，还鉴定了一种S.culsulatalis和A.mali。在这项研究中，这两种主要的脂环杆菌的发生率主要在梨的产品中（n=108；22.3％），桃子（n=99；20.5%），苹果（n=86；17.8%），和番茄（n=63；13％）。结果表明，从阿根廷的总分离株(n=414)中，巴西（n=54）和意大利（n=16）能够生产愈创木酚：107（25.8％），来自每个国家的33个（61.1%）和13个（81.2%）分离株，分别。PCA评分图表明，阿根廷和巴西分离株与愈创木酚和2,6-DCP/2,6-DBP的产量较高相关，分别。热休克后细胞存活的热图表明，愈创木酚产生水平不同的菌株根据腐败能力表现出不同的抗性。在120°C下3分钟的热休克中，没有任何一种脂环杆菌分离物可以幸免。这项工作提供了对发病率的见解，腐败潜力，从水果产品中分离出的脂环杆菌菌株的抗热震性。
