Isolation and characterization of phosphate-solubilizing bacteria from seagrass rhizosphere soil

Phosphate-solubilizing bacterial strains(6 Nos.) were isolated from the rhizosphere soils of two seagrasses(Halophila ovalis(R.Br.) Hook and Halodule pinifolia(Miki) Hartog) in the Vellar estuary.Experimental studies found that the strain PSSG6 was effective in phosphate solubilization with Phosphate Solubilization efficiency index E = 375 ± 8.54,followed by the strain PSSG5 with Phosphate Solubilization efficiency index E = 275 ± 27.3.Of the 6 strains isolated,the strains PSSG4 and PSSG5 be-longed to the genus Bacillus,and PSSG1,PSSG2 and PSSG3 were identified as Citrobacter sp.,Shigella sp.,and Klebsiella sp.,respectively,by conventional method,and PSSG6 was identified as Bacillus circulans using conventional and molecular methods.     

Isolation and Characterization of a Fucoidan-DegradingBacterium from Laminariajaponica

Fucoidan, a polysaccharide containing abundant fucose and sulfate ester group, was prepared from Laminaria japonica.In order to obtain fucoidan-degrading enzyme, bacteria capable of degrading fucoidan were screened from kelp. A bacterial strainnamed RC2-3 was obtained, which degraded fucoidan by the maximura extent of 54%±1.3%, the highest among all bacterial isolatesHigh-performance size exclusion chromatography （HPSEC） showed that the molecular weight of fucoidan was gradually reduced byRC2-3 with culturing time, suggesting the production of fucoidan-degrading enzyme by RC2-3. Phylogenetic analysis of partial 16Sribosomal RNA gene （16S rDNA） sequence showed that RC2-3 belonged to the family Flavobacteriaceae. However, it showed dif-ferent physiological and biochemical characteristics from the known Flavobacteriaceae members producing fucoidan-degradingenzyme, thus RC2-3 was proposed to be a new member of this family.     

具有多种胞外酶的对虾肠道黏附菌的分离和鉴定

用对虾饲料培养基从健康凡纳滨对虾肠道分离出500株黏附细菌,以产淀粉酶、脂肪酶和蛋白酶能力为指标,筛选出产该3种消化酶的细菌90株,占总菌株的18%.对其中生长较快的69株进行16S rDNA 基因测序,确定其分类地位.结果显示,69株菌分别属于不动杆菌属(Acinetobacter)、芽孢杆菌属(Bacillus)、葡萄球菌属(Staphylococcus)、假交替单胞菌属(Pseudoalteromonas)、气单胞菌属(Aeromonas)、嗜盐单胞菌属(Halomonas)、利斯顿氏菌属(Listonella)、莫拉氏菌属(Moraxella)等,其中数量最多是芽胞杆菌属,占鉴定细菌总数的53.62%,数量最少是气单胞菌属和嗜盐单胞菌属,均占鉴定细菌总数的2.90%.表明对虾肠道黏附菌群中具有较多能分泌多种消化酶的细菌,可进一步开发为促进对虾消化功能的益生菌     

Isolation and Characterization of Melanin Pigment from Yesso Scallop Patinopecten yessoensis

Melanin is one of the essential compounds in the pigments of molluscan shells.However,the effects of melanin on color variations in molluscs are largely unknown.Our previous study suggests that Yesso scallop Patinopecten yessoensis might contain melanin pigment in the dark brown shell.We therefore isolated melanin from the pigmented shells using hydrochloric acid method,and characterized the types of melanin pigments by spectrophotometry.The purified melanin,which was verified by spectrophotometry scanning and HPLC analysis,showed the typical characteristics of melanin absorption spectra and HPLC chromatograms.The contents of pheomelanin and eumelanin in pigmented shells,which were determined by the linear standard curve of melanin at 405 nm and 350 nm absorbance,were 48.23 ? 1.350 and 157.65 ? 5.905 mg,respectively.The present results indicate that the brown-pigmented shells of scallops comprise approximately 76.6% of eumelanin and 23.4% of pheomelanin,which supports the presence of eumelanin-rich pigment in scallop shells.Therefore,the combination of hydrochloric acid extraction and spectrophotometric quantification is a rapid and efficient method to isolate and quantify melanin in shells.This will facilitate the melanin studies related to shell color polymorphism and the selective breeding of bivalves with different shell colors.     

Isolation and Characterization of Collagen from Squid(Ommastreoges bartrami) Skin

Collagen of squid (Ommastrephes bartrami) skin was examined in the present study. Histology showed that collagen fiber in the skin was partially cross-linked with muscle fiber. Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from the skin and characterized. The results of amino acid composition and electrophoretic patterns revealed that ASC and PSC were both type Ⅰ collagen, containing α1 and α2 chains. FTIR (fourier transform infrared spectroscopy) investigations con-firmed the existence of helical arrangements in PSC of squid skin. The denaturation temperature (Td) and shrinkage temperature (Ts)of PSC were 29.4℃ and 52.8℃, respectively.     

Isolation and Characterization of Collagen from Squid(Ommastrephes bartrami) Skin

Collagen of squid(Ommastrephes bartrami) skin was examined in the present study. Histology showed that collagen fiber in the skin was partially cross-linked with muscle fiber. Acid-solubilized collagen(ASC) and pepsin-solubilized collagen(PSC) were extracted from the skin and characterized. The results of amino acid composition and electrophoretic patterns revealed that ASC and PSC were both type Ⅰ collagen,containing α1 and α2 chains. FTIR(fourier transform infrared spectroscopy) investigations confirmed t...     

Extraction,Isolation and Structural Characterization of Polysaccharides from a Red Alga Gloiopeltis furcata

Three kinds of polysaccharides:GFW,GFH and GFA,were sequentially extracted from a red alga Gloiopeltis furcatawith 25℃and 85℃water,and 60℃ 4%NaOHwater solution.Based on the defatted alga,the yields of the polysaccharide were57.9%,2.5%and 2.6%,respectively.Their monosaccharide compositions,average molecular weights and structural characters weredetermined by gas chromatography(GC),high performance liquid chromatography(HPLC),fourier transform infrared spectroscopy(FTIR)or13C-NMR spectroscopy.The results showed that GFW,GFH and GFA were all composed of D-galactose(Gal)and3,6-anhydro-L-galactose(AnG),and particularly GFA also contained xylose(Xyl).The average molecular weights of GFW,GFHand GFA were 22.6 kD,26.5 kD and 49.8 kD,respectively,with the respective sulfate content 31.2%,25.1%and 22.7%.The data ofFTIR and13C-NMR confirmed the sulfate ester location at C6 of galactose.It is concluded that all the three polysaccharides extractedfrom Gloiopeltis furcata were sulfated galactans,two being sulfated-agarose,and one being xylose-containing sulfated galactan.     

Isolation,Expression and Characterization of rbcL Gene from Ulva prolifera J.Agardh (Ulvophyceae,Chlorophyta)

Ulva prolifera is a typical green alga in subtidal areas and can grow tremendously fast. A highly efficient Rubisco enzyme which is encoded by Up Rbc L gene may contribute to the rapid growth. In this study, the full-length Up Rbc L open reading frame(ORF) was identified, which encoded a protein of 474 amino acids. Phylogenetic analysis of Up Rbc L sequences revealed that Chlorophyta had a closer genetic relationship with higher plants than with Rhodophyta and Phaeophyta. The two distinct residues(aa11 and aa91) were presumed to be unique for Rubisco catalytic activity. The predicted three-dimensional structure showed that one α/β-barrel existed in the C-terminal region, and the sites for Mg~(2+)coordination and CO_2 fixation were also located in this region. Gene expression profile indicated that Up Rbc L was expressed at a higher level under light exposure than in darkness. When the culture temperature reached 35℃, the expression level of Up Rbc L was 2.5-fold lower than at 15℃, and the carboxylase activity exhibited 13.8-fold decrease. Up Rbc L was heterologously expressed in E. coli and was purified by Ni~(2+) affinity chromatography. The physiological and biochemical characterization of recombinant Rubisco will be explored in the future.     

Characterization of Fe(III)-Reducing Enrichment Cultures and Isolation of Enterobacter sp. Nan-1 from the Deep-Sea Sediment,South China Sea

To characterize the Fe(III)-reducing bacteria, enrichment cultures were initiated by inoculating deep-sea sediment from the South China Sea (SCS) into the