[目的]探究聚苯乙烯微塑料对球形棕囊藻(Phaeocystis globosa)生长的影响,为微塑料和致灾赤潮藻复合污染的生态效应以及海洋生态系统保护研究提供科学依据.[方法]在以f/2培养基为培养介质、初始密度为2000 mL-1的球形棕囊藻藻液中添加小粒径(直径0.1、1.0μm)及大粒径(直径10.0、100.0、1000.0μm)聚苯乙烯微塑料,扩大培养30 d,分析不同粒径微塑料对球形棕囊藻单细胞密度、囊体数量、囊体直径以及囊体细胞密度的影响.[结果]微塑料对球形棕囊藻游离单细胞生长有明显的抑制作用(P<0.05);大粒径微塑料的抑制作用较强,10.0μm组和1000.0μm组的抑制率最高分别为99.3％及99.2％.微塑料可使实验组囊体数量显著低于对照组(P<0.05),大粒径微塑料对囊体数量的抑制率均在94.0％以上,并延缓囊体的形成时间.微塑料对球形棕囊藻囊体直径的增大有显著促进作用(P<0.05);大粒径微塑料对囊体直径增长率最高分别达到2633.4％(30 d)、2515.1％(27 d)及1868.2％(27 d).微塑料对球形棕囊藻囊体细胞的生长有明显的促进作用(P<0.05),小粒径微塑料的促进作用明显大于大粒径微塑料,培养至30 d,0.1、1.0μm组囊体单细胞密度增长率已分别达到52249.4％、47666.3％.[结论]聚苯乙烯塑料微球可抑制球形棕囊藻游离单细胞的生长,延迟球形棕囊藻形成囊体的时间,减少囊体数量,增加囊体直径,增加囊体细胞密度.大粒径(10.0、100.0、1000.0μm)微塑料对游离单细胞密度、囊体数量、囊体直径影响较大,而小粒径(0.1、1.0μm)微塑料则对囊体细胞的生长有更加明显的促进作用.

Phaeocystis globosa blooms frequently in the Beibu Gulf of China. This species has a distinct life cycle that includes colonies and solitary cells. Colonies are formed during a bloom, while solitary cells are produced between blooms. Information about the abundance of solitary cells and other picophytoplankton in the northern Beibu Gulf is limited. To elucidate phytoplankton variation trends during periods of frequent P. globosa blooms and to determine the main physiochemical factors affecting phytoplankton distribution, four cruises were conducted between November 2018 and April 2019. Seawater was collected, and water temperature, salinity, and nutrient concentrations were simultaneously determined. Redundancy analysis was performed to understand the relationship between environmental factors and phytoplankton assemblages. Seven phytoplankton clusters were present during the cruises. Picophytoplankton abundance (including Synechococcus and Picoeukaryote groups I and II) dominated during the four cruises. Synechococcus abundance was restricted by the low temperatures in winter, decreasing from November to February and increasing in April. Picoeukaryote I abundance was almost unaffected by low temperatures and was mainly affected by nutrient concentration. P. globosa solitary cell abundance increased from November to January and decreased in February and April, and phosphorus was the key factor affecting P. globosa blooms. This is the first study to reveal the abundance and distribution of P. globosa solitary cells in this area.

球形棕囊藻(Phaeocystis globosa)是近年来北部湾常见的有害藻华原因种,涠洲岛海域作为广西沿海藻华的高发区之一,目前仍缺乏关于该海域球形棕囊藻藻华过程的相关研究.为探究涠洲岛海域球形棕囊藻藻华过程中营养盐的状况及藻华的发生对浮游植物群落组成的影响,对2017年3月下旬涠洲岛周边发生的球形棕囊藻藻华区域进行取样调查.结果表明,藻华期间水体中溶解有机磷含量与细胞及囊体密度呈显著正相关.本次藻华主要受水体中溶解态无机氮含量影响,多个调查站点的无机氮/无机磷(DIN/DIP)<10,且硅酸盐/无机氮(SiO32-/DIN)>1,表明这些站点存在氮限制现象,而氮限制可能是本次藻华消亡的主要因素.调查区域共鉴定出浮游植物4门58种,球形棕囊藻细胞密度最高可达1.04×108 cells/L,占浮游植物总细胞密度的98.28％.球形棕囊藻细胞密度与物种多样性指数存在显著的负相关关系.在营养缺乏条件下,有利于球形棕囊藻成囊的链状硅藻种类具有相对较大的细胞密度.

球形棕囊藻(Phaeocystis globosa Scherffel)主要以囊体形态形成赤潮,由单细胞向囊体形态的转变是赤潮爆发的关键.本研究推测囊体形成的前提是游离单细胞达到一定密度阈值,当密度低于该阈值时,囊体无法形成.基于此,本文探究了不同条件(温度、营养充气搅动、摄食压力、初始密度)下囊体形成时游离单细胞的密度.结果显示:不同培养条件下,囊体形成所需的游离单细胞密度不一致,但都达到了104 cells/mL的数量级;稀释试验表明,利用f/2培养基稀释使游离单细胞的密度小于104 cells/mL时,囊体不能形成,而密度大于104 cells/mL的游离单细胞对照组,在24 h内便有囊体形成.总的来说,游离单细胞在高密度情况下更容易形成囊体.

Bifunctional alginate lyase can efficiently saccharify alginate biomass and prepare functional oligosaccharides of alginate.

Alginate lyases are a group of enzymes that catalyze the depolymerization of alginates into oligosaccharides or monosaccharides. These enzymes have been widely used for a variety of purposes, such as producing bioactive oligosaccharides, controlling the rheological properties of polysaccharides, and performing structural analyses of polysaccharides. The algM4 gene of the marine bacterium Vibrio weizhoudaoensis M0101 encodes an alginate lyase that belongs to the polysaccharide lyase family 7 (PL7). In this study, the kinetic constants Vmax (maximum reaction rate) and Km (Michaelis constant) of AlgM4 activity were determined as 2.75 nmol/s and 2.72 mg/mL, respectively. The optimum temperature for AlgM4 activity was 30 °C, and at 70 °C, AlgM4 activity dropped to 11% of the maximum observed activity. The optimum pH for AlgM4 activity was 8.5, and AlgM4 was completely inactive at pH 11. The addition of 1 mol/L NaCl resulted in a more than sevenfold increase in the relative activity of AlgM4. The secondary structure of AlgM4 was altered in the presence of NaCl, which caused the α-helical content to decrease from 12.4 to 10.8% and the β-sheet content to decrease by 1.7%. In addition, NaCl enhanced the thermal stability of AlgM4 and increased the midpoint of thermal denaturation (Tm) by 4.9 °C. AlgM4 exhibited an ability to degrade sodium alginate, poly-mannuronic acid (polyM), and poly-guluronic acid (polyG), resulting in the production of oligosaccharides with a degree of polymerization (DP) of 2–9. AlgM4 possessed broader substrate, indicating that it is a bifunctional alginate lyase. Thus, AlgM4 is a novel salt-activated and bifunctional alginate lyase of the PL7 family with endolytic activity.

[Objective] A marine Vibrio X511 with strong ability to use alginate was isolated from the rotten Sargassum in the Weizhou Island of the North Sea.The metabolic pathway of using alginate by Vibrio X511 was studied by transcriptome sequencing.[Methods] Transcriptions sequencing was done by Illumina Hi Seq2500 sequencing platform and the transcriptome of the strains cultured in alginate and glucose were sequenced.Differential transcripts were compared and analyzed, and the sequencing results were confirmed by fluorescence quantitative PCR.The fluorescence quantitative PCR was applied to verify the sequencing results.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were used to annotate the function and pathway in differential transcripts.[Results] There were 2024 differentially expressed genes in the culture of alginate compared to those in glucose, with 1066 genes up-regulated and 958 genes down-regulated.Some genes in the ubiquitous metabolic pathway were also differentially expressed in different cultures.The transcriptions of all the genes involved in alginate utilization and the key genes of synthetic ethanol in Vibrio X511 were up-regulated.In addition, the strain had a unique way to utilize alginate and one of the metabolic processes has not been reported in Vibrio.[Conclusion] Our findings enrich the research of biological method for degradation of alginate, and provide valuable data for the research of large seaweed biomass-based energy.

The alginate lyase gene in marine Vibrio sp.X511 was expressed by Escherichia coli to realize the large-scale preparation of alginate lyase and research enzymatic properties.By analyzing the sequence,the first 20 amino acids of the enzyme were predicted as the signal peptide,the protein molecular mass without the signal peptide was 30 254.28 Da,the isoelectric point was 8.75,the molecular formula was C1368H2100N364O401S6,and the corresponding gene sequence was named as alg1987.The construction program of bacteria recombination was as follows:the specific nucleic acid primers were designed and the alg1987 was obtained by PCR;the recombinant plasmid pET-30(a)-alg1987 was introduced into E.coli Trans5t for sequencing;the positive plasmid pET-30(a)-alg1987 was extracted and introduced into E.coli BL21,then expressed by the induce of IPTG.The supematant of recombinant bacteria cytosol was induced and detected by SDS-PAGE,it was found that the molecular mass of the alginate lyase by heterologous expression was similar to the predicted value.The expression conditions of alginate lyase in recombinant bacteria were optimized.The results showed that optimum parameters were as follows:induction temperature 16 ℃,time 16 h,induction agent IPTG concentration 0.8 mmol/L.

2014年3月1-4日在广西沿岸44个站位进行了浮游植物群落结构的现场凋查,对春季广西北部湾浮游植物群落的种类组成、优势种、丰度以及多样性的时空变化特征进行研究,并应用典范对应分析(CCA)分析了环境因子对浮游植物群落结构的影响.共鉴定出浮游植物6门56属120种(含变种、变型),其中硅藻36属98种(包含变种、变型),占所有物种数的81.67％;甲藻11属13种,占所有物种数的10.83％.浮游植物数量变化范围为0.52× 104～54.47× 104 cell/L,平均密度为9.78×104cell/L,高值区主要分布在珍珠湾西侧和钦州港附近海域.硅藻平均细胞数量为6.53×104/L,甲藻平均细胞数量为0.41×104/L.主要优势种为薄壁几内亚藻、(Guinardia cylindrus)、脆根管藻(Rhizosolenia fragillissima)、球形棕囊藻(Phaeoecystis globosa)、赤潮异弯藻(Heterosiga akashiwo)、中肋骨条藻(Skeletonema costatum)、斯托根管藻(Rhizosolenia stolterfothii).分析结果显示,2014年春季广西北部湾浮游植物H'值和J值均较低,浮游植物群集稳定性较差;温度、pH值、DIP和COD是影响春季浮游植物群落的主要环境因子,研究成果可为深入了解环境变化对该海域浮游植物群落结构的影响提供基础资料.

To control seafood quality and regulate oyster aquaculture in Qinzhou Harbor, Beibu Gulf, the oysters (Crassostrea rivularis) were collected from three stations in the region in 2015, and analyzed by atomic fluorescence spectrophotometer and atomic absorption spectrometer. Overall, the content of heavy metals in Crassostrea rivularis exhibited Zn>Cu>Cd>Cr>As>Pb>Hg, and contents of Zn and Cu had the average of 532.03 and 126.96 mg/kg, respectively. Referring to aquatic products standard of NY 5073-2006, we found, with the exception ofCrassostrea rivularis collected at the 2nd station of July, the level of Cu from 89% samples exceeded the limit. While referring to aquatic products standard of GB 2762-2012, only the level of samples from the 3rd station of July went beyond the limit. Contents of Pb and Hg were low, with an average of 0.02 and 0.009 mg/kg, respectively. The dietary intakes of heavy metals in Qinzhou Harbor's Crassostrea rivularis were lower than the recommended values of Joint FAO Expert Committee on Food Additives (JECFA), thus the oysters in this region are safe for edibility.

采用响应面法优化海洋弧菌X511的产酶发酵培养基,提高其胞内褐藻胶裂解酶产量.通过单因素试验研究了不同碳源、不同氮源、海藻酸钠、氯化钠、蛋白胨、硫酸亚铁、硫酸镁和磷酸氢二钾对菌株产胞内酶活力的影响,在此基础上,利用Plackett-burman试验确定海藻酸钠、氯化钠、蛋白胨和硫酸镁对胞内酶产量的影响.通过响应面试验构建回归方程,结果表明,最佳发酵培养基成分为海藻酸钠9.0 g/L,NaC1 31.6 g/L,蛋白胨15.0g/L,MgSO4·7H2O 1.5 g/L.在此条件下,该菌株的胞内褐藻胶裂解酶的活力为(20.65±0.14) U/mL,较优化前的酶活提高了64.4％.

于2014年1月（冬季）和10月（秋季）对钦州湾海域进行了综合调查,分析了该海区分粒级Chl a的分布特征及其影响因素。结果表明,冬季Chl a平均浓度为2.38μg/L,秋季Chl a浓度显著升高,平均浓度为6.96μg/L。浮游植物粒级结构具有明显的季节变化特征,冬季浮游植物粒级组成以微型浮游植物为主,平均占Chl a总量的73.0%,小型和微微型浮游植物所占的比例分别为14.9%和12.1%;秋季,小型、微型和微微型浮游植物对Chl a总量的贡献率分别为42.3%、44.7%和12.9%。浮游植物平均粒级指数秋季（23.55μm）显著大于冬季（11.23μm）。从空间分布上看,在高营养盐含量区域大粒径的浮游植物占有优势,而其他靠近外海一侧的站位则以微型浮游植物为主。温度、营养盐和悬浮物是影响钦州湾海域浮游植物粒级Chl a分布和组成的重要环境因子。

根据2009-2011年对广西钦州湾海域的综合调查结果,采用《近岸海洋生态健康评价指南》中的河口及海湾生态系统健康评价方法对该海域的生态系统健康状况进行评价与分析.结果显示,水环境健康指数、沉积环境健康指数、生物残毒健康指数、栖息地健康指数、生物健康指数分别为14.61,9.93,9.00,7.50,13.38,海域生态系统健康指数为54.42.表明,钦州湾近岸海域水环境和沉积环境都处于健康状态,未受生物残毒污染,而栖息地和生物指标分别处于不健康状态.综合5类评价因子的评价结果,判定该海域生态环境处于亚健康状态.

Objective]Distribution and seasonal variation of chemical oxygen demand (COD) in the coastal surface waters of Fangchenggang were analyzed,and the correlation between the environmental factors and the distribution of COD was discussed.[Methods]Based on the field data from four cruises and 12 stations of oceanographic survey carried out in the coastal waters of Fangchenggang from the June 2010 to March 201 1,the sea surface water spatial and temporal distribution of COD and its influence factors are discussed by using standard in-dex method and correlation method.[Results ]The result indicated that COD standard index>1 occurred in the top of the West Bay, the Fangcheng river estuaries. The COD concentrations of other stations met the first-rate National Seawater Quality Standard.There was a positive correlation between the COD con-centrations and temperature in each season and the larger correlation coefficient was 0.575 in spring. COD concentration was in significant&nbsp;negative correlation to salinity (r < 0.860,P < 0.01).Additionally,COD concentration was significantly correlated with chlorophyll a in spring (r = 0.910,P < 0.01)and winter (r =0·957,P < 0.01).In contrast,the correlation coefficient is relatively low in summer(0.606) and the autumn(0.592).The correlation coefficient between the concentration of COD and suspended solids was above 0.800 in spring and summer,0.694 in autumn,and 0.478 in win-ter.[Conclusion]Horizontal distribution of COD showed similar patterns in different seasons in Fangchenggang.Areas with high value of COD concentration were found offshore while COD concentration in open sea was relatively low.COD concentrations decreased gradually from offshore to open sea.Results showed the COD concentration in the coastal waters of Fangchenggang was mainly correlated with terrestrial input,especially the river runoff.In addition,the COD concentration was also affected by phytoplankton.

Based on the survey data of the seawater quality of the coastal waters of the eastern Qinzhou Bay in the autumn of 2011, the seawater quality is comprehensively assessed by the single factor standard index method and fuzzy comprehensive evaluation model. The results show that the concentration of DO, COD, BOD5, PO4-P, DIN, petroleum, Cu, Pb, Zn, Cd, Cr, As and Hg in seawater averages 6.34 mg/L, 1.10 mg/L, 0.74 mg/L, 0.02 mg/L, 0.26 mg/L, 0.023 mg/L, 2.2 μg/L, 1.1 μg/L, 4 μg/L, 0.14 μg/L, 0.2 μg/L, 0.68 μg/L and 0.036 μg/L, respectively. Only the mean concentrations of PO4-P and DIN exceed the National Se awate r Quality Standard of the first category. Assessing by the single factor standard index method and fuzzy comprehensive evaluation model, the seawater quality of the eastern Qinzhou Bay is classified as II and I level, respectively. Therefore, the main pollutants in the eastern Qinzhou Bay in autumn are PO4-P and DIN.

[目的]分离筛选具有抗荔枝霜疫霉菌和荔枝炭疽病菌活性的海洋真菌,为新型生物抗菌剂的研究开发提供理论依据.[方法]采用平板分离法从广西北部湾近岸海域红树林区的海洋沉积物样品中分离单个真菌菌株,以平板对峙法和菌丝块法对具有抗菌活性的菌株进行筛选,对筛选出的真菌进行耐盐度试验,并通过形态学观察及分子生物学试验对海洋真菌的种类进行鉴定.[结果]从海洋沉积物样品中共分离出58株海洋真菌,其中2株海洋真菌(HZ02和HZ05)对荔枝霜疫霉菌和荔枝炭疽病菌具有较好的抑制效果,其发酵液对荔枝霜疫霉菌菌丝相对生长抑制率分别为94.27％和96.44％,对荔枝炭疽病菌菌丝生长相对抑制率分别为56.31％和73.43％.耐盐度试验结果表明,2株海洋真菌可在无盐及低盐条件下生长.形态学观察及分子生物学鉴定结果表明,海洋真菌HZ02为草酸青霉(Penicillium oxalicum),HZ05为阿达青霉(Penicillium adametzii).[结论]分离筛选出的2株海洋真菌HZ02和HZ05菌株对荔枝霜疫霉、荔枝炭疽病具有良好的拮抗作用,具有作为生物抗菌剂的潜力.

In order to understand the current situation of the intertidal macrobenthic animals in Beilun estuary, the survey was carried out in November 2011. Three intertidal sections were set, each contained 3 quadrats in random. 63 species were collected altogether, including 29 species of molluscs, 18 of crustaceans, 12 of polychaetes, and 4 of others. The dominant species were Cerithidea cingulata, Mictyris longicarpus, Diopatra chilienis and Diogenes penicillatus. The average total biomass and average total density of macrobenthic animals were 155.06 g/m2 and 343.8 ind/m2. The average value of Shannon-Wiener index (H') was 2.27, 0.48 of evenness index (J) and 3.53 of species richness index (d). The results of the ABC analysis showed that all of the 3 intertidal sections were disturbed modestly. MPI of theⅠ-Ⅲsections were 2.61, 0.16 and-17.08, respectively. Intertidal environmental quality of the study area was affected in a certain degree. The study suggested that the human activities such as overfishing and herding ducks were the main disturbing factors.

为研究钦州湾大型底栖动物的生态特征,探讨影响大型底栖动物分布的主要因素,于2011年5月在钦州湾进行大型底栖动物调查,并同步采集沉积物样品,进行理化性质分析.使用Surfer软件绘制各群落特征指数的平面分布图,用SPSS软件分析群落特征指数与沉积物环境因子之间的关联性.共采集到大型底栖动物种类55种.平均生物量为105.48 g/m2,平均密度为50ind/m2.香农-维纳指数(H')、种类均匀度指数(J')和丰富度指数(D)的平均值分别为1.44,0.63和0.64.群落特征指数与沉积物环境因子之间的相关性分析结果显示,密度与Cu,Pb,Zn,Cd,Cr,Hg以及有机碳呈显著负相关;种类数与所分析的10项沉积物环境因子之间均呈显著负相关;均匀度指数与Hg和有机碳呈显著负相关;丰富度指数与硫化物呈显著负相关;生物量和香农-威纳指数与沉积物各环境因子之间均没有显著的相关性.

采用纯培养法对广西茅尾海海域海洋沉积物中的细菌进行分离纯化,得到24株可培养海洋细菌.采用基于16SrRNA基因序列的系统发育分析对其中13株细菌进行多样性研究,发现分属于4门5属13种,其中菌株QZ-16与Formosa spongicola A2T最接近,相似比为95.5％,初步可判断为新的Formosa菌种属.利用滤纸片法对菌株的抑制病原或致病菌活性进行初步筛选,发现其中10株细菌对4株指示菌具有抑制作用.采用卤虫致死法测试菌株的生物毒活性,试验结果表明,其中3株菌株具有较强的卤虫致死活性,其余菌株活性较弱或无活性.

采用批量平衡吸附实验研究了广西红树林沉积物对诺氟沙星的吸附特性,以及pH、盐度和表面活性剂等对吸附的影响.结果表明,诺氟沙星在沉积物上的吸附过程包括快速吸附和慢速吸附两个阶段;在实验浓度范围内吸附等温线呈非线性,可用Freundlich模型和Langmuir模型进行良好的拟合.在pH为3～10时,诺氟沙星的平衡吸附量随pH的增大,先增后减;而平衡吸附量随盐度的上升呈下降的趋势.在表面活性剂浓度为5.00 mg/L时,3种类型表面活性剂对诺氟沙星在红树林沉积物上吸附均有促进作用,作用由弱到强依次为:Tween20＜ SDBS＜ CTAB.