一株海洋来源蛋白酶产生菌Parengyodontium album HX2019006的鉴定及其发酵条件研究

为筛选1株产蛋白酶的海洋菌种,课题组从厦门市红树林中筛选得到1株产蛋白酶的丝状真菌,并对其细胞形态进行了扫描电镜观察,经提取其ITS序列于Genbank进行比对并构建进化树,将其鉴定为Parengyodontium album HX2019006。该菌株在海水培养基中可生产蛋白酶,通过对其培养基组分及发酵条件进行单因素优化,获得较高的蛋白酶产量后,选择培养基中麦芽糖浓度、蛋白胨浓度和培养时间3个因素进行3水平响应面优化,在优化后的培养基和发酵条件下,发酵液蛋白酶活力为71. 1 U/m L,较初始条件提高125. 7%。

Adhesion of pathogenic Vibrio alginolyticus to the gill mucus of Pseudosciaena crocea

Adhesion of Vibrio alginolyticus to the gill mucus of Pseudosciaena crocea has been investigated using [ methyl-^3 H ] thymidine as isotope tracer. The results showed that： the adhesive quantity of V. alginolyticus increased with bacterial concentrations and reached equilibrium after incubated for 180 min; the higher adhesive quantity was obtained at 15 ~ 30 ℃ and sourish conditions; adhesion of V. alginolyticus could not achieved without Na^＋ , and Ca^2＋ played an auxiliary role in the bacterial adhesion; adhesion of V. alginolyticus was inhibited remarkably by starvation, heat treatment and periodic acid treatment; all of the eight kinds of carbohydrates investigated enhanced the adhesion of V. alginolyticus to the gill mucus of P. crocea, among them, glucose, mannose, fructose and maltose showed the specially enhanced adhesion. The results indicated that E alginolyticus could adhere to the gill mucus of P. crocea facilely in seawater, and this bacterial adhesion was influenced by environmental factors and closely related to superficial carbohydrate structures and some heat-sensitive structures.

产DHA破囊壶菌Aurantiochytrium sp.HX2019010的筛选及其脂肪酸组成分析

为筛选产二十二碳六烯酸(Docosahexaenoic acid,DHA)菌株,从厦门市红树林的海水腐木中分离到一株球状真菌HX2019010,通过扫描电镜观察,测定ITS序列,与Genbank数据库比对,该菌株与破囊壶菌相似性较高。选取ITS序列相似性较高的相近菌株构建的进化树表明,菌株HX2019010与Aurantiochytrium类群聚为一枝,自举检验值较高,初步定名为Aurantiochytrium sp.HX2019010。该菌株在发酵罐中可产生较高浓度的DHA,98 h发酵后生物量达108.27 g/L,总油脂达28.43 g/L,DHA达9.17 g/L。细胞脂肪酸组成分析结果表明,该菌株所产脂肪酸主要为棕榈酸、DHA、肉豆蔻酸等;脂肪酸组成受培养时间或培养条件的影响,总量可达细胞干质量的26.26%,其中DHA占脂肪酸总量的32.25%-45.86%。

Separation and Enrichment of Melamine in Feed by a New Molecularly Imprinted Solid-phase Extraction Column

[ Objective] The research aimed to develop a new molecular imprinting solid-phase extraction column for the separation and enrichment of melamine in feed. [ Method] The molecular imprinting polymer of melamine was prepared by mass polymerization method. This polymer was used as filler to prepare molecular imprinting polymer solid-phase extraction（MIP-SPE） column of melamine. The solid-phase extraction conditions were optimized and melamine content in concentrated solution was determined by using HPLC. [ Result] Melamine eould be separated selectively from feed and enriehed by self-made MIP-SPE column. It could wipe off complex matrix from feed and the addition recovery rate was 95%. The contrast experiment between MIP-SPE column and NMIP-SPE （ non-imprinted polymer- solid phase extraction） column showed that the extraction efficiency of the former was obviously higher than the latter. [ Conclusion] The home-made MIP- SPE column could be used to separate and enrich melamine in feed efficiently, with a broad application prospect.

Starvation effects on pathogenic Vibrio alginolyticus in natural seawater

To get a better understanding of the starvation survival strategy of pathogenic Vibrio alginolyticus, log-phase cells were inoculated into sterile natural seawater for starvation studies. The results showed that all of total bacteria number, viable bacteria number and CFU number of V. alginolyticus increased remarkably at the initial starvation stage; after reaching their peaks at 5 d, both total bacteria number and viable bacteria number of V. alginolyticus fell slowly, while the CFU number fell more quickly after reaching its peak at 10 d; V. alginolyticus elongated their cells at the prophase of starvation, and then shrunk their volume and turned their shapes into ovals from rods at the anaphase of starvation; starved cells showed more sensitivity to heating and UV; starved cells showed no significant difference from unstarved ones at the lowest detection limit determined by indirect enzyme-linked immu- nosorbent assay （ELISA） ; starved cells＇ ability to adhere to the skin mucus of large yellow croaker （ Pseudosciaena crocea） showed a sharp decline as the starvation time increases; the cellular protein of V. alginolyticus increased remarkably at the ariaphase of starvation. The results indicated that pathogenic V. alginolyticus could survive in starvation for relatively long periods of time （ ≥2 months） in 28℃ natural seawater due to the morphological and physiological changes; however, starved V. alginolyticus cells showed less virulence and higher sensitivity under environmental stresses.

Distribution and Migration Patterns of Lead in Atmosphere-tea System by Isotopic Tracing Method

With low concentration of stable lead isotope as the tracer, using inductively coupled plasma mass spectrometry （ICP-MS）, the lead absorption of tea plants as well as the distribution and migration pattern of lead in plants under different pH environments and spraying introduction of lead sources were studied through pot trial. The results showed that tea plants were very sensitive to atmospheric lead source pollution; atmospheric lead source pollution had a tendency of moving up to the top （bud） ; low pH conditions enhanced lead absorption of plants and promoted upward migration of lead in plants. The experimental method is closer to the actual situation that plants are exposed to low concentration pollution, and could distinguish experimentally introduced lead source from environmentally introduced lead source.

A Device for Rapid Detection of Dithiocarbamate Pesticide Residues in Fruits

Based on the chemical properties of dithiocarbamate pesticides,a device for rapid detection was developed in the paper,and the experimental conditions were optimized. Dithiocarbamate residues in fruits were successfully detected using molecular absorption spectro-photometry,and the recovery rate was over 80%.The rapid detection method was simple to operate with low cost,and was conducive to application in basic level and enterprise laboratories.

厦门市售蔬菜、茶叶重金属含量及健康风险评价

为研究厦门市售蔬菜和茶叶中重金属含量特征并评价其对人体的健康风险,分析测定了厦门市主要农贸市场的10种蔬菜和主要商场的10种茶叶中重金属含量,运用内梅罗综合污染指数对重金属污染水平进行评价,运用靶标危害系数法(THQ)对重金属人体健康风险进行评估。结果表明:厦门市售蔬菜和茶叶不同品种中Zn、Cu、As、Cd和Pb含量差异较大,其中As、Cd和Pb含量均低于植物样品(蔬菜和茶叶)中各重金属元素食品卫生标准限值;蔬菜和茶叶中重金属As、Cd和Pb均处于安全等级(P_综≤0.7),其中,蔬菜中Cd的单项污染指数最高,茶叶中Pb的单项污染指数最高,两种元素均有较大危害,应重点关注;蔬菜和茶叶中重金属Zn、Cu、As、Cd、Pb对儿童的靶标危害系数基本高于成人,各重金属的单一靶标危害系数(THQ)及综合危害系数(TTHQ)均小于1,说明不存在明显的健康风险。

福建省茶园土壤-茶叶的铅含量及铅同位素示踪

运用微波消解-电感耦合等离子体质谱法（ICP-MS）分析了福建省内9个市县的茶园土壤和茶叶的铅含量及铅同位素组成,评价铅污染情况并解析铅来源。结果表明,茶园土壤和茶叶的铅含量分别为23.00±0.099～55.43±0.032 mg/kg和0.53±0.126～1.47±0.058 mg/kg,地质累积指数法表明茶园土壤基本为无污染,单项因子指数法表明茶叶均为安全等级。茶园土壤和茶叶铅同位素组成具有区域性,茶叶铅同位素组成相对于茶园土壤具有较低的206Pb/207Pb和206Pb/208Pb。结合铅含量相关性分析和铅同位素示踪分析,福建省茶叶铅主要来源于茶园土壤和大气。福建省茶叶铅同位素组成的同地相似性和异地差异性特征可为茶叶产地溯源和鉴别提供一定的科学依据和参考价值。

基于全基因组序列的新型冠状病毒SARS-CoV-2多算法进化树分析

新型冠状病毒(SARS-CoV-2)作为一种RNA病毒,具有高突变率的特征,自新型冠状病毒肺炎(COVID-19)发生以来,病毒基因组已出现了一定程度的突变,可以通过进化分析对其进行分类,以辅助分析病毒感染源。由于时间较短,总体突变率仍然较低,利用单一算法构建的进化树结构可靠性不高。本文用Paup、MrBayes和MEGA软件,通过不同算法构建进化树,对目前GenBank中所有的SARS-CoV-2基因组进行了分析。不同算法所得到的多个进化树中,部分序列分支结构相同或相似,且相应的病毒宿主间可能存在交集,通过比较分析多个树之间的相似结构,可为病毒的来源提供参考信息。随着病毒的进化和基因组数据库的不断积累,预计利用多算法构建进化树去筛选相同分枝结构的方法的有效性将逐步提升,可作为感染源分析的参考方法之一。