Evaluation of different culture media and enrichment in orange juice upon the growth of Alicyclobacillusspp.

Bacteria of the genus Alicyiclobacillus spp. form spores and develop in acid media, leading to the spoilage of citrus juices. Brazil is the largest exporter of orange juice concentrate, and yet, it has been extensively studied due to changes in taste and smell. Several investigations have reported different culture media used to detect and enumerate Alicyiclobacillus spp. The objective of the present study was to evaluate the recovery of Alicyiclobacillus spp. spores grown in ALI, BAT, K agar and YSG media using the methodology suggested by ABECitrus. Five inocula were used, two from reference strains and three from pasteurized concentrated orange juice. Cell recovery after the enrichment in reconstituted orange juice was also analyzed. An initial population of 6 log CFU/mL was inoculated. ALI, BAT and YSG media were able to recover the initial population of all different inocula, with no significant differences between the results. When compared to BAT, however, the preparation of ALI and YSG media was simpler and had more advantages. The recovery with K agar medium was lower than the other media for all the tested inocula, with significant differences found for Alicyclobacillus acidocaldarius0298T (3.66 log CFU/mL) and Alicyclobacillus pomorum-like CBMAI 0278 (4.11 log CFU/mL).

环酸芽孢杆菌属（Alicyclobacillus）细菌可形成芽孢并在酸性培养基中生长繁殖，进而导致柑橘汁变质。巴西是浓缩橙汁的最大出口国，受该菌引发的产品风味与气味异常问题影响，相关研究已得到广泛开展。多项研究已报道了多种用于检测与计数环酸芽孢杆菌属细菌的培养基。本研究旨在采用ABECitrus建议的检测方法，评估ALI、BAT、K琼脂及YSG四种培养基对培养所得环酸芽孢杆菌属芽孢的回收效果。本次实验共设置5份接种物：2份源自标准菌株，3份取自巴氏杀菌浓缩橙汁。同时，本研究还分析了经复原橙汁增菌后的菌体回收情况。实验接种的初始菌落数为6 log CFU/mL。结果显示，ALI、BAT及YSG培养基均可回收所有接种物的初始菌落数，各组检测结果无显著差异。但相较于BAT培养基，ALI与YSG培养基的配制流程更为简便，优势更为突出。对于所有受试接种物，K琼脂培养基的回收效果均低于其余三种培养基；其中，酸热环酸芽孢杆菌（Alicyclobacillus acidocaldarius）0298T（回收值为3.66 log CFU/mL）与类苹果环酸芽孢杆菌（Alicyclobacillus pomorum）样菌株CBMAI 0278（回收值为4.11 log CFU/mL）的检测结果差异显著。