Hastings J W, Holzapfel W H, Niemand J G
Appl Environ Microbiol. 1986 Oct;52(4):898-901. doi: 10.1128/aem.52.4.898-901.1986.
Of 113 lactobacilli isolated from radurized (5 kGy) minced meat, 7 Lactobacillus sake strains, 1 L. curvatus strain, and 1 L. farciminis strain were used for radiation resistance studies in a semisynthetic substrate (i.e., modified MRS broth). Five reference Lactobacillus spp., one Staphylococcus aureus strain, and one Salmonella typhimurium strain were used for comparative purposes. All L. sake isolates exhibited the phenomenon of being more resistant to gamma-irradiation in the exponential (log) phase than in the stationary phase of their growth cycles by a factor of 28%. Four references strains also exhibited this phenomenon, with L. sake (DSM 20017) showing a 68% increase in resistance in the log phase over the stationary phase. This phenomenon was not common to all bacteria tested and is not common to all strains with high radiation resistance. Four L. sake isolates and three reference strains were used in radiation sensitivity testing in a natural food system (i.e., meat). The bacteria were irradiated in minced meat and packaged under four different conditions (air, vacuum, CO2, and N2). Organisms exhibited the highest death rate (lowest D10 values [doses required to reduce the logarithm of the bacterial population by 1] ) under CO2 packaging conditions, but resistance to irradiation was increased under N2. The D10 values of the isolates were generally greater than those of the reference strains. The D10 values were also higher (approximately two times) in meat than in semisynthetic growth medium.
从经5千戈瑞辐照的碎肉中分离出的113株乳酸菌中，选取7株清酒乳杆菌、1株弯曲乳杆菌和1株豕肠球菌用于在半合成培养基（即改良MRS肉汤）中进行抗辐射研究。选取5株参考乳杆菌属菌株、1株金黄色葡萄球菌和1株鼠伤寒沙门氏菌用于对比。所有清酒乳杆菌分离株在其生长周期的指数（对数）期比稳定期对γ射线辐照的抗性更强，抗性因子为28%。4株参考菌株也表现出这种现象，清酒乳杆菌（DSM 20017）在对数期的抗性比稳定期增加了68%。这种现象并非所有受试细菌都有，也并非所有高抗辐射性菌株都有。选取4株清酒乳杆菌分离株和3株参考菌株在天然食品体系（即肉类）中进行辐射敏感性测试。将细菌在碎肉中进行辐照，并在4种不同条件（空气、真空、二氧化碳和氮气）下包装。在二氧化碳包装条件下，微生物的死亡率最高（D10值[使细菌数量对数减少1所需的剂量]最低），但在氮气条件下对辐照的抗性增加。分离株的D10值通常高于参考菌株。在肉类中的D10值也比在半合成生长培养基中更高（约两倍）。
