1株铜绿微囊藻降解菌的分离鉴定及其溶藻特征

以铜绿微囊藻为供试藻类,从发生黄化的铜绿微囊藻液中分离出了1株溶藻细菌H1.对溶藻细菌H1进行的生理鉴定和16S rDNA序列分析结果表明该菌株为短芽孢杆菌属.H1菌对于铜绿微囊藻的降解特性表明:该株溶藻细菌对于铜绿微囊藻有很好的去除效果,1 d后叶绿素去除率达到了71.6%,7 d后叶绿素去除率为80.48%.在溶藻过程中,营养物质氮和磷从藻细胞内转移到了藻细胞外.

1株铜绿假单胞菌JM1的溶藻特征

富营养化水体的水华爆发严重影响了水环境质量,成为急需解决的环境问题。该文研究了1株水体土著菌Pseudomonas aeruginosa JM1在不同条件下的生长和溶藻特征。结果表明：菌株JM1的牛肉膏蛋白胨发酵液在一次性投加时溶藻效果明显好于少量连续滴加方式,即添加量一定时溶藻活性物质对铜绿微囊藻的累积毒性小于急性毒性。菌株JM1发酵液不仅可快速杀死铜绿微囊藻细胞,还可分解利用藻细胞的残体及其分泌物,从而能够将藻细胞快速从水体中去除。菌株JM1发酵液对铜绿微囊藻的溶解作用随着藻细胞初始密度的增加而下降。以牛肉膏蛋白胨为培养基时,适宜菌株JM1生长的pH为5~9,而且在pH为10时仍可生长,但pH〈4和〉11时菌株JM1无法生长,菌株JM1在生长过程中能够将培养液的pH主动调节成适宜生长的中性或偏碱性。菌株JM1发酵液经过酸碱变化,仍然保持较强的溶藻活性,但与未处理的相比,溶藻效果略有下降,说明发酵液中可能含有微量的其他溶藻或助溶藻物质,在pH变化过程中活性消失。研究结果表明菌株Pseudomonas aeruginosa JM1在水体的水华控制和应急除藻方面具有较高的应用价值。

一株溶藻细菌的分离、筛选与分子鉴定

为了筛选对铜绿微囊藻有溶藻活性的菌株,采用试管法筛选溶藻效果好的细菌,显微观察高效溶藻菌的溶藻作用方式,对其热稳定性、耐酸碱能力及紫外稳定性进行考察,并采用16S r DNA序列分析鉴定溶藻菌种类。共筛选获得7株具有溶藻效果的细菌,其中F15菌株对铜绿微囊藻溶藻效果最好。菌株F15的溶藻活性物质为胞外产物,当其生长到对数期时,其胞外产物的溶藻效果达到最大,按体积比1∶6将其加入藻液,培养3 d后,铜绿微囊藻的去除率达55%以上。该溶藻活性产物对加热、酸碱及紫外线处理均具有较好的稳定性。16S r DNA序列分析表明,F15菌株与Bacillus cereus strain ATCC 14579同源性最高,达99%,被鉴定为蜡状芽孢杆菌。F15菌株溶藻效果好,稳定性高,具有开发成生物控藻菌剂的潜在价值。

Characteristics of the tertiary egg membrane of cuttlefish Sepiella maindroni de Rochebrune

We separated tertiary egg membrane （TGM） from 2- and 25-day-old eggs of cuttlefish Sepiella maindroni de Rochebrune, and revealed its ultrastructure, physical （solubility, barrier property） and biochemical （histology, histochemistry, nutritional components, bacteriostasis） characteristics. The results show that TGM could not be dissolved with natural seawater, alcohol, ether or hydrochloric acid （HC1）, but it could be dissolved with 2-chloroethanol, diethylamine, and sodium hydroxide （NaOH）. The black TGM was more effective in blocking off mud particulates, microorganisms （Chlorella vulgaris, Vibrio alginolyticus） and lighter than the white TGM. The elasticity of black and white TGMs was 1.8 N and 1.5 N, respectively. There were some ink particulates and rod-shaped bacteria in the black TGM. The nutritional components were different between black and white TGMs： Lipid content was lower and protein content was higher in the black TGM. TGM could also inhibit the growth of Vibrio alginolyticus.

Three-dimensional fluorescence characteristics of dissolved organic matter produced by Prorocentrum donghaiense Lu

Filtration and cross-flow ultrafiltration techniques were used to separate culture media of Prorocentrurn donghaiense at the exponential growth, stationary and decline stages into 〈0.45 μm filtrate, 100 kDa-0.45 μm, 1%100 kDa and 1-10 kDa retentate and 〈1 kDa ultrafiltrate fractions. The fluorescence properties of different molecular weights of dissolved organic matter （DOM） were measured by excitation-emission matrix spectra. Protein-like and humic-like fluorophores were observed in the DOM produced by P. donghaiense. The central positions of protein-like fluorophores showed a red shift with prolonged growth duration, shifting from tyrosine-like properties at the exponential growth stage to tryptophan-like properties at the stationary and decline stages. The excitation wavelengths of protein-like fluorophores exhibited some change in the exponential growth and stationary stages with increased molecular size, but showed little change in the decline stage. However, the emission wavelengths in the decline stage exhibited a blue shift. Very distinct C type and A type peaks in humic-like fluorophores were observed. With a prolonged culture time, the intensities of both of the peaks became strong and the excitation wavelengths of peak A showed a red shift, while the A：C ratios fell. More than 94% of fluorescent DOM was in the lower than 1 kDa molecular weight fraction.

2株球形棕囊藻溶藻细菌的分离及鉴定

从珠海赤潮海水中分离出2株溶藻细菌Y01和Y04,对球形棕囊藻均有显著的溶藻效果.结果表明,溶藻细菌Y01和Y04均为革兰氏阳性菌,对球形棕囊藻的溶解作用时间为6 d.借助显微镜及扫描电镜等观察Y01和Y04溶藻过程,发现2株溶藻细菌的溶藻方式均为直接裂解藻细胞.溶藻细菌Y01和Y04的16S rDNA系列分析表明,溶藻细菌Y01和Y04的PCR扩增产物的长度分别为1 468 bp和1 548 bp(登录号分别为DQ531607和DQ531608).菌株Y01和Y04与多株芽孢杆菌的16S rDNA核苷酸序列的同源性在99.7%以上,均归属于芽孢杆菌属.