木糖氧化无色杆菌反硝化亚种细菌的分离鉴定及其菲降解特性研究

利用选择性富集培养及升华法,从石油污染的土壤中分离到2株菲降解细菌,它们在以菲为唯一碳源的培养基上生长良好。应用BIOLOG细菌鉴定系统和分子生物学方法对两株细菌进行鉴定,两株菌分别为坚强芽孢杆菌(Bacillus.firmus)和木糖氧化无色杆菌反硝化亚种(Achromobacter.xylosoxidanssub.sp.denitrificans),两株菌均具有邻苯二酚氧化酶活性。两株细菌在液体培养条件下都表现较强降解菲的能力,液体培养60.h约90%的加入菲被降解。通过测定液体培养基中菲浓度和菌体密度变化发现,菌株降解菲的量与其生长密度相关;随着菌体浓度(吸光度)的增加,代谢底物菲的浓度明显降低,两株菌混合使用能够大幅度提高降解菲的能力。     

噬氨副球菌HPD-2固体发酵条件优化及其对PAHs污染土壤的修复效果

选用有机肥A、有机肥B和紫花苜蓿粉3种有机物料作为菌剂载体,探讨了固体发酵过程中物料量、接种量、固水比和发酵时间对噬氨副球菌HPD-2生长的影响,以及固体发酵菌剂对PAHs污染土壤的修复效果。结果表明,3种发酵载体中,以有机肥A的效果最好。噬氨副球菌HPD-2以有机肥A为载体的固体发酵最佳条件为物料量20 g、接种量5%、固水比1:1、发酵时间 144 h。菌剂施入土壤28天后,土壤中PAHs总含量由初始的9.96 mg/kg 下降到7.64 mg/kg,其去除率达22.8%。不同环数PAHs的去除率高低顺序为3环＞5环＞6环和4环,分别下降了35.1%、27.0%、20.7%、20.4%。该菌剂对PAHs污染土壤有一定的修复效果。     

木瓜秀粉蚧在海南的适生性及空间分布型研究

木瓜秀粉蚧是热带和亚热带地区重要的危险性害虫,本研究利用最大熵模型(Max Ent)和地理信息系统(GIS)软件,依据该虫的分布数据和20个环境因子预测其在海南的适生性,并对木瓜秀粉蚧在木薯地中的空间分布型进行了分析。结果表明:木瓜秀粉蚧在海南的高度适生区主要有陵水、乐东、东方、昌江、海口西部等地,模型的AUC值为0.982,表明该模型预测结果可靠;影响其分布的主要环境因子有年均降水量、最冷季度平均温度、年温度变化范围和最湿润季度降水量等,因子贡献率分别为23.7%、16.5%、14.2%和12.1%;用聚集度指标法确定木瓜秀粉蚧在木薯上一定密度下的空间分布为聚集分布,并采用m*-m回归法和Taylor幂法则对其进行了验证;成虫在木薯植株上的分布,表现为上、中层的虫口密度显著高于下层。研究结果对提高木瓜秀粉蚧的监测和防控水平具有指导意义。     

A molecular detection and identification method for papaya mealybug （Paracoccus marginatus）, the first recorded invasive pest in Fujian province of China北大核心CSCD

【Objective】Paracoccus marginatus Williams and Granara de Willink is an invasive pest with strong diffusion and fecundity. It has caused serious damage to the papaya industry in Central America, Florida (USA), Guam (USA) and India. Pa. marginatus was first discovered in Fujian Province (Fuzhou and Zhangzhou) in 2017, showing great potential risks to papaya and other fruit crops, as well as flower industry in Fujian province. Because of the small body size and similar morphological characteristics, the morphological identification of mealybugs was inefficient. Rapid molecular identification of different species could be achieved through the use of DNA barcoding technology. Therefore, a technology for rapid molecular identification of Pa. marginatus was established based on the species-specific PCR method. 【Methods】A species-specific PCR method based on ribosomal DNA-28S gene fragment (28S rDNA) was exploited to establish one technology for rapid detection and identification of Pa. marginatus. The additional 10 species of mealybugs (Phenacoccus solenopsis, Dysmicoccus boninsis, Nipaecoccus viridis, Phenacoccus solani, Pseudococcus comstocki, Pseudococcus cryptus, Planococcus lilacinus, Pseudococcus odermatti, Planococcus minor and Phenacoccus madeirensi) were collected in the fields as the contrast. In order to ensure the uniqueness of the source of DNA, the DNA templates were all extracted from one single female adult of these 11 species of mealybugs, respectively. 28S rDNA of the 11 species was amplified by a pair of universal primers (S3660/A335). The obtained partial fragments of 28S rDNA were sequenced. And the phylogenetic tree was established by using a Neighbor-joining (NJ) method. According to the obtained 28S rDNA gene partial sequence of the 11 species and 28S rDNA gene sequences of Paracoccus galzerae in GeneBank database, the sequence alignment and analysis were performed on DNAMAN. 28S rDNA species-specific primers (28S-ParF/ 28S-MarR) for Pa. marginatus were designed by selecting the sites with large differences in the sequence. And then, the specific effects, versatility and sensitivity of the specific primers were examined. 【Results】The comparative results showed that the similarity between Pa. marginatus and Paracoccus marginatus isolate S3-668, KP692333 in the GenBank database was 100%. It was also indicated that the mealybugs were identified as Pa. marginatus by molecular identification. Phylogenetic analysis indicated that Pa. marginatus from Fuzhou and Zhangzhou was clustered in a clade. And that combined with Paracoccus galzerae (inter-species genetic distance is 0.058) to form a clade of the genus Paracoccus. The results of specificity tests showed that all Pa. marginatus specimens could be detected positively and a 446 bp fragment of the 28S rDNA of Pa. marginatus was obtained by the species-specific primers, while there was no cross reactions with other 10 species of mealybugs. The species-specific primers not only had a stable amplification effect on female adults, but also were proved to be applicable for the 2nd instar nymphs and the 3rd instar nymphs. Pa. marginatus from three different regions (Fuzhou and Zhangzhou in Fujian province, Jinghong in Yunnan province) and six different host plants (Carica papaya, Solanum melongena, Plumeria rubra, Solanum tuberosum, Tithonia diversifolia and Duranta erecta) was also successfully detected by the species-specific primers.【Conclusion】Molecular identification of Pa. marginatus first reported in Fujian province was carried out based on 28S rDNA molecular markers. It was proved by experiments that the 28S rDNA species-specific primers had ideal and stable specificity for Pa. marginatus and could be used to identify Pa. marginatus accurately. A rapid molecular detection technique for Pa. marginatus was established based on the species-specific PCR method. The technology has the characteristics of accuracy, rapidity, sensitivity and simplicity. Our present results indicated that the rapid detection technique should be useful in quarantine at ports, in pest detection and in monitoring during transportation of papaya and other fruit tree seedlings, as well as flowers. However, in view of the fact that no other mealybugs of the genus Paracoccus has been reported in China, this study can provide a reference for the molecular identification for the closely related species of Pa. marginatus. © 2019 Journal of Fruit Science     

A highly effective polycyclic aromatic hydrocarbon-degrading bacterium, Paracoccus sp. HPD-2, shows opposite remediation potential in two soil types

Bioaugmentation is an efficient and eco-friendly strategy for the bioremediation of polycyclic aromatic hydrocarbons(PAHs). Since the degrading abilities of soils can greatly alter the abilities of PAH-degrading bacteria, illustrating the potential and mechanism of highly efficient degrading bacteria in different soil environments is of great importance for bioremediation. A PAH-degrading bacterium, Paracoccus aminovorans HPD-2, and two soil types,red and paddy soils, with distinct PAH-degrading...     

外来危险性入侵害虫木瓜秀粉蚧的危害与防控

木瓜秀粉蚧原产于墨西哥和中美洲,是危害热带和亚热带水果、蔬菜和园林植物的重要害虫.介绍了该虫的野外特征、地理分布、寄主植物、生物学及经济重要性,并提出了生物防治、物理防治、加强检疫、化学防治等方面的防控措施及预防建议.     

一株异养硝化细菌的分离鉴定和脱氮特性研究

筛选对高浓度NH3-N养殖废水具有高效硝化能力的菌株,研究其硝化性能。通过比较几种已报道的筛选方法和不同生境中异养硝化细菌筛选效果,确定了以乙酰胺为唯一碳源和氮源,从高氨氮生境中可以筛选到高效的异养硝化细菌;进一步通过富集培养分离,从沼气池出水口水中分离到一株异养硝化细菌,并根据部分长度的16S rDNA序列进行了系统发育分析。该菌株具有高效异养硝化功能,在初始氨氮浓度为104 mg·L-1的异养氨化培养基中培养12 h后,氨氮和总氮去除率分别达81.7%和53.7%,最终氨氮和总氮去除率可达90.1%和61.3%,且培养液中无明显的硝酸盐氮和亚硝酸盐氮累积。16S rDNA的序列分析鉴定,该菌株与Paracoccus denitrificans具有99%相似性,结合生理生化分析认定该菌株是一株脱氮副球菌,命名为Paracoccus denitrificans FJAT-14899。筛选出的菌株Paracoccus denitrificans FJAT-14899对氨氮具有高效的去除率,显示了良好的应用前景。     

木瓜秀粉蚧为害对不同木薯品种次生代谢物质含量的影响

次生代谢物质在植物防御植食性害虫时发挥重要作用,但目前尚无次生代谢物质与木薯品种抗虫相关性的报道。本研究系统开展了木瓜秀粉蚧为害前后不同木薯品种叶组织中总酚、丙二醛、单宁等次生代谢物质含量的差异分析。结果表明,与为害前相比,木瓜秀粉蚧为害1、4、8 d后,感虫木薯品种‘BRA900’‘面包’‘SC205’和‘瑞士T7’叶组织中总酚与丙二醛含量无显著差异,单宁含量则显著降低,而抗虫木薯品种‘缅甸’和‘C1115’叶组织中总酚和单宁含量显著增加,丙二醛含量显著降低。抗虫木薯品种的总酚含量在粉蚧为害前显著低于感虫木薯品种,而粉蚧为害1、4、8 d后显著高于感虫木薯品种;抗虫木薯品种丙二醛含量在为害前与感虫木薯品种无显著差异,粉蚧为害1、4、8 d后显著低于感虫木薯品种;抗虫木薯品种单宁含量在为害前后均显著高于感虫木薯品种。相关性分析发现,木薯对木瓜秀粉蚧的抗性与叶组织中总酚含量和单宁含量显著正相关,与丙二醛含量显著负相关。本研究初步阐明基于次生代谢物质总酚、丙二醛、单宁的木薯品种对木瓜秀粉蚧的抗性机理。     

优化VB12发酵工艺 提高经济效益

进行了甜菜碱不同加量对脱氮假单胞杆菌发酵产VB12影响的实验。结果表明,甜菜碱减量对VB12发酵单位不但无显著负影响,反而可以提高发酵单位。在此基础上考察了发酵培养基中甜菜碱不同加量对VB12发酵单位的影响,发酵培养基中甜菜碱的量由7．0g／L降至3．0g／L,对VB12发酵单位无显著影响;还考察了补料中甜菜碱减量对VB12发酵单位的影响,补料中甜菜碱量由30g/L降至15g/L,对VB12发酵单位无显著影响。