目的在沉香性状、显微和理化鉴别、浸出物含量测定的基础上,通过探讨不同品种间的r DNA TIS2序列差异及系统发育分析,为商品沉香的鉴定提供分子生物学依据。方法以白木香、商品沉香及人工诱导沉香为材料,对其进行醇溶性浸出物测定、性...
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目的在沉香性状、显微和理化鉴别、浸出物含量测定的基础上,通过探讨不同品种间的r DNA TIS2序列差异及系统发育分析,为商品沉香的鉴定提供分子生物学依据。方法以白木香、商品沉香及人工诱导沉香为材料,对其进行醇溶性浸出物测定、性状及显微鉴别,提取总DNA、扩增r DNA ITS2片段并直接测定序列,MEGA5.0软件计算种内种间Kimura 2-parameter(K2P)遗传距离并进行系统发育分析,构建邻接树(NJ)和最大简约树(MP)。结果人工沉香、商品沉香醇溶性浸出物含量均高于10%,性状和显微鉴别均符合《中国药典》(2010年版)一部有关规定。沉香种内平均K2P遗传距离为0-0.003,种间平均K2P遗传距离为0.005-0.023。白木香、人工沉香和商品沉香在系统发育树上聚为一支。结论在沉香性状、显微和理化鉴别、浸出物含量分析的基础上,基于ITS2条形码序列可以准确鉴别沉香基源植物,为商品沉香的鉴定提供分子生物学依据。
Listeria monocytogenes is a major foodborne pathogen that is well known as high mortality rate upon *** study aimed to investigate the occurrence of *** isolates from a meat product processing plant in China and chara...
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Listeria monocytogenes is a major foodborne pathogen that is well known as high mortality rate upon *** study aimed to investigate the occurrence of *** isolates from a meat product processing plant in China and characterize the isolates of *** by antibiotic resistance, virulence potential and genetic diversity analyses.A total of 86 food and environment samples were *** the qualitative and quantitative methods, 10 samples (11.6%) were positive for *** 29 isolates in this survey were sensitive to gentamicin, kanamycin, sulbactam/ampicillin, trimethoprim-sulfamethoxazole,tetracycline and doxycycline, the highest resistance is rifampicin (41.4%), followed by penicillin (24.1%) and ciprofloxacin (24.1%).Ten isolates were susceptible to all 17 tested antibiotics;thirteen isolates were resistant to more than two antibiotics, which most of them isolated from raw material and equipment of the meat product processing *** isolates were carried hly (29/29, 100%), inlB (23/29, 79.3%), inlA (29/29, 100%), inlC (29/29, 100%), inlJ (29/29, 100%), actA (19/29, 65.5%), iap (29/29, 100%), plcA (26/29, 100%), plcB (29/29,100%) and prfA (27/29, 93.1%).Further study of inlA sequencing showed most of strains (25/29, 86.2%) contained full-length InlA that required for host cell invasion, whereas three mutations lead to premature stop codons (PMSC).*** isolates belonged to serovar 1/2a (3a) and 1/2b (3b, 7) and multilocus sequence typing (MLST) revealed that these *** strains belonged to 5 different sequence *** accordance with these results, the control of *** should focus on the raw *** study also reflects the potential risk of *** infection from different *** Listeria monitoring programs will allow for improved development of Listeria control measures in order to minimize cross-contamination in finished products.
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