Isolation and characterization of microsatellite loci from mangrove red snapper Lutjanus argentimaculatus

Lutjanus argentimaculatus, also called mangrove red snapper, is a commercially important fish in East Asia. A proper understanding of population structure is primarily linked with the management of genetic resources in exploiting marine fisheries. Herein, seven microsatellite loci, which showed high polymorphism (observed heterozygosity per locus ranging from 0.3571 to 0.7857 and expected heterozygosity per locus ranging from 0.6236 to 0.8821), were isolated and characterized from L. argentimaculatus. Cross-species amplifications also indicate that primers designed for these loci may be useful for further studies about other closely phylogenetic species of the family Lutjanidae.

Population genetic structure of crimson snapper Lutjanus erythropterus in East Asia, revealed by analysis of the mitochondrial control region

The population genetic structure of the crimson snapper Lutjanus erythropterus in East Asia was examined with a 427-bp hypervariable portion of the mtDNA control region. A total of 262 samples were collected and 75 haplotypes were obtained. Neutrality tests (Tajima's and Fu's) suggested that Lutjanus erythropterus in East Asia had experienced a bottleneck followed by population expansion since the late Pleistocene. Despite the low phylogeographic structures in mtDNA haplotypes, a hierarchical examination of populations in 11 localities from four geographical regions using analysis of molecular variance (AMOVA) indicated significant genetic differentiation among regions (Phi(CT) = 0.08564, p < 0.01). Limited gene flow between the eastern region (including a locality in the western Pacific Ocean and two localities in the East Sea) and three geographic regions of the South China Sea largely contributed to the genetic subdivision. However, comparisons among three geographic regions of the South China Sea showed little to no genetic difference. Populations of Lutjanus erythropterus in East Asia are inferred to be divided into two major groups: an eastern group, including populations of the western Pacific Ocean and the East Sea, and a South China Sea group, consisting of populations from northern Malaysia to South China. The results suggest that fishery management should reflect the genetic differentiation and diversity in East Asia. (c) 2006 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.

己酸乙酯酯化真菌筛选及发酵条件研究

本文主要研究了具有己酸乙酯酯化活性的真菌菌株的筛选和发酵条件优化。从大曲和糟醅样品中分离纯化获得79株产生透明圈的丝状真菌，菌落形态初步识别结果显示分离菌株包括红曲霉属、根霉属及曲霉属等菌株。其中菌株EM-56酯化酶活力最强，发酵获得的粗酶制剂酶活为172.36 u。根据显微形态、菌落形态及生理生化特征，初步鉴定该菌株为曲霉科红曲霉属紫色红曲霉（Monascus purpureus）。 在此基础上重点研究了菌株EM-56在不同培养基成分及不同培养条件下的产酶情况，确定了最佳培养基和培养条件。通过单因素实验确定在基础培养基中添加最佳碳源为葡萄糖，最佳氮源为蛋白胨。正交优化实验结果确定了最佳培养基组成：以麸皮为基础培养基，添加葡萄糖 2%，蛋白胨 0.3 %，KH2PO4.3H2O 0.05 %，MgSO4.7H2O 0.06 %。菌株EM-56在上述培养基中的最佳发酵条件为：初始pH 5.5，发酵温度为35°C，发酵时间7d，种龄48h，接种量8%，装瓶量50g / 瓶（500mL）。在最佳培养基和发酵条件下，菌株EM-56发酵获得的粗酶制剂酶活达到241.56 u，比优化前提高了40.15%。 In this paper, the research focuses on the selection of fungus with esterifying activity and optimization of fermentation conditions. We isolated 79 strains which had transparent zones from Daqu and fermented grains. The isolated strains contained Monascus、Rhizopus and Aspergillus through primary morphology analysis. The strain of EM-56 which produces strongest esterase was selected. The enzyme activity reached 172.36u. According to related literature, EM-56 was identified as Monascus purpureus through morphology analysis and biochemical determination. We also studied the effects of different medium and fermentation conditions on the esterase production of strain EM-56. The optimal medium and fermentation conditions were determined. Single factor experiment result shows that the optimal carbon source added is glucose and the optimal nitrogen source added is peptone. The optimal fermentation medium determined by orthogonal optimization test is as follows: wheat bran as substrate, glucose 2%, peptone 0.3%, KH2PO4.3H2O 0.05%，MgSO4.7H2O 0.06%. The optimal fermentation conditions are: initial pH 5.5, cultural temperature 35°C, cultural time 7d, seed age 48h, inoculation 8%, medium mass 50g / flask（500mL）. The esterse activity of EM-56 cultivated in the optimal medium and fermentation conditions reached 241.56u and increased by 40.15% compared with the original activity.

Species identification in salted products of red snappers by semi-nested PCR-RFLP based on the mitochondria 12S rRNA gene sequence

A molecular approach was developed to distinguish species of red snappers among commercial salted fish products. The specific fragments of the mitocliondrial 12S rRNA gene, which were about 450 bp, were obtained using the semi-nested polymerase chain reaction (semi-nested PCR). Subsequently, PCR amplicons were sequenced, aiming to select restriction endonucleases that generated species-specific restriction fragment length polymorphism (RFLP) profiles. Discrimination of red snappers Lutjanus sanguineus, L. erythopterus from L. argentintaculatus, L. malabarius and other morphologically similar fishes such as Lethrinus leutjanus and Pinjalo pinjalo was feasible by one restriction digestion reaction with three endonucleases Hae III, Sca I and SnaB I, however, for differentiation of L. sattguineus and L. erythopterus, another restriction digestion reaction with single restriction endonuclease Mae II was needed. The seminested PCR-RFLP was demonstrated to be reliable in species identification of salted fish products in this study. (c) 2005 Published by Elsevier Ltd.

Species identification in salted products of red snappers by semi-nested PCR-RFLP based on the mitochondrial 12S rRNA gene sequence

A molecular approach was developed to distinguish species of red snappers among commercial salted fish products. The specific fragments of the mitochondrial 12S rRNA gene, which were about 450bp, were obtained using the semi-nested polymerase chain reaction (semi-nested PCR). Subsequently, PCR arnplicons were sequenced, aiming to select restriction endonucleases that generated species-specific restriction fragment length polymorphism (RFLP) profiles. Discrimination of red snappers Lutjanus sanguineus, Lutjanus erythopterus from Lutjanus argentimaculatus, Lutjanus malabarius and other morphologically similar fishes such as Lethrinus leutjanus and Pinjalo pinjalo was feasible by one restriction digestion reaction with three endonucleases Hae III, Sca I and SnaB I, however, for discrimination of L. sanguineus and L. erythopterus, another restriction digestion reaction with single restriction endonuclease Mae II was needed. The semi-nested PCR-RFLP was demonstrated to be reliable in species identification of salted fish products in this study. (c) 2005 Elsevier Ltd. All rights reserved.

高产Monacolin K红曲菌株的复合诱变选育

利用紫外线和氯化锂对一株紫红曲Monascus purpureus 菌株进行复合诱变试验。在最佳紫外照射时间为45s 和最佳氯化锂浓度为1.0‰的情况下，获得了一株Monacolin K 高产突变菌Monascu purpureus ZT32 且连续传接5 代产量稳定，用紫外分光光度法检测其Monacolin K 含量为219.9μg/mL，较原始菌株高出2 倍多，然后将其用于固态发酵，结果表明：红曲米中的Monacolin K 的含量达到8.33mg/g，是原始菌株的3.3 倍。