水稻体内细菌的动态研究

经过对水稻两品种(沈农319、中百4号)不同时期、不同组织内生细菌动态变化研究结果表明,根组织带菌量最高,其次是叶,茎最低。发育阶段以孕穗期带菌量显着增高,随着组织衰老而降低。对分离到的4个主要种群显着性检验结果表明,巨大芽孢杆菌为两品种体内细菌优势种。通过对水稻这一世界性粮食作物体内细菌的种类,以及随生育期、组织间菌体数量变化的探讨研究,为水稻害虫的生物防治,提供遗传改良工程杀虫细菌的有效载体菌。     

水稻体内细菌的动态研究

经过对水稻两品种（ 沈农３１９ 、中百４ 号） 不同时期、不同组织内生细菌动态变化研究结果表明,根组织带菌量最高,其次是叶,茎最低．发育阶段以孕穗期带菌量显著增高,随着组织衰老而降低．对分离到的４ 个主要种群显著性检验结果表明,巨大芽孢杆菌为两品种体内细菌优势种．通过对水稻这一世界性粮食作物体内细菌的种类,以及随生育期、组织间菌体数量变化的探讨研究,为水稻害虫的生物防治,提供遗传改良工程杀虫细菌的有效载体菌．     

The rumen microbiology of seaweed digestion in Orkney sheep

The microbial populations of the rumens of seaweed-fed and pasture-fed Orkney sheep were examined. The populations in the pasture-fed sheep were similar to those of other domestic ruminants fed on land plants, but those of the seaweed-fed animals showed major differences in the dominant species. Total ciliate populations were quantitatively similar, but in the seaweed-fed animals Dasytricha ruminantium was one of the most dominant species. No phycomycete fungi or cellulolytic bacteria were found in the seaweed-fed animals, and the bacterial population was dominated by Streptococcus bovis, Selenomonas ruminantium, Butyrivibrio fibrisolvens and lactate-utilizing species. Electron microscopy revealed that spirochaetes and an unidentified filamentous bacterium were probably of major significance in seaweed digestion. The ability of bacterial strains from both groups of animals to metabolize plant and algal constituents was examined.     

Bacterial communities in predatory mites are associated with species and diet types

The symbiotic bacterial communities of phytophagous arthropods are affected by host species and feeding habits, but such effects have been poorly studied in natural enemies. Here, we investigated the entire bacterial microbiome of two species of predatory mites, Neoseiulus californicus and Neoseiulus barkeri, feeding on three types of diets (artificial diet, pollen and their natural prey, the spider mite Tetranychus urticae) by high-throughput sequencing of the 16S rRNA gene. We found that the bacterial diversity of predatory mites feeding on artificial diet was significantly different from pollen and spider mite feeding groups in both N. californicus and N. barkeri, while bacterial diversity also differed strikingly between the two species even when feeding on the same artificial diet. This finding suggests that the bacterial community of predatory mites is determined by both species and diet. Alphaproteobacteria and Gammaproteobacteria were the two dominant bacterial classes in both predatory mite species, except for N. californicus feeding on artificial diet. The bacterium Bosea sp. was detected in all samples as the core microbial species in predatory mites. Additionally, we discuss whether Bradyrhizobiaceae and Rhodobacteraceae bacteria could be used as probiotics in the artificial diet of N. californicus for better mass rearing.

     

The rumen microbiology of seaweed digestion in Orkney sheep

The microbial populations of the rumens of seaweed-fed and pasture-fed Orkney sheep were examined. The populations in the pasture-fed sheep were similar to those of other domestic ruminants fed on land plants, but those of the seaweed-fed animals showed major differences in the dominant species. Total ciliate populations were quantitatively similar, but in the seaweed-fed animals Dasytricha ruminantium was one of the most dominant species. No phycomycete fungi or cellulolytic bacteria were found in the seaweed-fed animals, and the bacterial population was dominated by Streptococcus bovis, Selenomonas ruminantium, But yrivibrio fibrisol-vens and lactate-utilizing species. Electron microscopy revealed that spirochaetes and an unidentified filamentous bacterium were probably of major significance in seaweed digestion. The ability of bacterial strains from both groups of animals to metabolize plant and algal constituents was examined.     

Toxicity of the entomopathogenic bacteria Photorhabdus and Xenorhabdus to the mushroom mite (Luciaphorus sp.; Acari: Pygmephoridae)

The mushroom mite, Luciaphorus sp. is a serious pest of tropical mushrooms. We determined the pathogenicity and toxicity of species and strains of the entomopathogenic bacteria, Photorhabdus and Xenorhabdus to the mite. As these bacteria are known to produce antifungal substances, we first determined the effect of 21 species and strains of the bacteria on the mycelial growth of the mushroom, Lentinus squarrosulus. We then determined the toxicity of the eight species and strains of bacteria that did not show any effect on mushroom growth against both the female and male mites. All eight species and strains of the bacteria were toxic to the female mite resulting in significant mite mortality within 24-48 h. Cell-free supernatants from all the eight bacterial species and strains were also toxic to the female mite inflicting significant mortality within 24-48 h. The supernatants of two strains, GPS12 and GPS11, of Photorhabdus luminescens ssp. laumondii were significantly more toxic than the other species and strains to the female mite, resulting in 90-95% mite mortality within 48 h. Both the concentration and age of the bacteria had significant effect on the toxicity of the supernatants to the female mite. None of the bacteria showed toxicity to the male mite which has undeveloped mouthparts. These results indicate that P. luminescens ssp. laumondii and its byproducts are directly toxic to the female mite, suggesting the potential of developing a novel biological approach for the control of this mushroom pest. This is the first report on the miticidal activity of the entomopathogenic bacteria, Photorhabdus and Xenorhabdus.     

污损生物膜细菌Pseudoalteromonas issachenkonii YT1305-1的鉴定及其代谢物化学成分分析

【目的】对污损生物膜细菌YT1305-1进行菌种鉴定;研究其作为污损生物膜优势菌之一的代谢产物。【方法】通过16S rRNA基因序列分析,结合系统进化树和细菌生理生化实验对菌种进行鉴定,通过硅胶柱层析分离方法和核磁共振检测技术分析其代谢物的化学成分。【结果】发现生物膜中存在明显的优势菌株,假交替单胞菌属为优势菌属之一。16S rRNA序列比对分析表明Pseudoalteromonas issachenkonii为优势菌种之一,将目标菌种命名为Pseudoalteromonas issachenkonii YT1305-1,对其代谢物化学成分进行分析,共得到10个化合物,其中包括5个二酮哌嗪(DKPs)类信号分子,环(甘氨酸-丙氨酸)(1)、环(脯氨酸-甘氨酸)(2)、环(脯氨酸-酪氨酸)(3)、环(4-羟基-脯氨酸-亮氨酸)(4)和环(4-羟基-脯氨酸-丙氨酸)(5),以及尿嘧啶(6)、胸腺嘧啶(7)、胸腺嘧啶脱氧核苷(8)、己二酸二(2-乙基己)酯(9)和邻苯二甲酸二(2-乙基己)酯(10)。【结论】污损生物膜中存在明显的优势菌,其中之一为P.issachenkonii YT1305-1,在其代谢产物中发现了疑似信号分子的物质DKPs,有研究表明该物质能调控生物膜的形成,进而影响生物污损的形成,为探究生物污损现象奠定了物质基础。     

Mycophagous mites and their internal associated bacteria cooperate to digest chitin in soil

The greater bulk of soil nitrogen is immobilized in chitinous cell walls of fungi. Mycophagous soil mites participate in chitin decomposition and, hence, in the subsequent mobilization of nitrogen. The source of the chitinolytic enzymes was searched in this study. A multimethodical approach was designed for these studies. Histology, plating and identification of bacteria from mite homogenate and, finally, homogenate and bacterial treatment of the soil fungi were applied. Here the presence and activity of chitinolytic bacteria inside mycophagous mites are reported. These bacteria form an extraintestinal group within the mite’s body and pass their enzymes into the mite’s gut. Our results demonstrate that true mycophagous mites, defined by their ability to digest chitin (i.e. the fungal cell wall), achieve this through internal “cooperation” with chitinolytic bacteria that provide the necessary chitinolytic enzymes. The nitrogen from chitin is thus made available to other soil organisms and plants.     

Dominant bacterial communities in the rumen of Gayals (Bos frontalis), Yaks (Bos grunniens) and Yunnan Yellow Cattle (Bos taurs) revealed by denaturing gradient gel electrophoresis

The dominant rumen bacteria in Gayals, Yaks and Yunnan Yellow Cattle were investigated using PCR-DGGE approach. The analysis of DGGE profiles, identification of dominant bands and phylogenetic analysis 16S rDNA sequences in DGGE profiles were combined to reveal the dominant bacterial communities and compared the differences between those cattle species. DGGE profiles revealed that Gayals had the most abundant dominant bacteria and the lowest similarity of intraspecies between individuals than other two cattle species. A total of 45 sequences were examined and sequence similarity analysis revealed that Gayals had the most sequences appeared to uncultured bacteria, accounting for 85.0% of the total sequences, Yaks and Yunnan Yellow Cattle had 44.4 and 68.8% uncultured bacterial sequences, respectively. According to phylogenetic analysis, the rumen dominant bacteria of Gayals were mainly phylogenetically placed within phyla firmicutes and bacteroidetes, and the known bacteria were mainly belonged to the genera Lachnospiraceae bacterium, Ruminococcus flavefaciens and Clostridium celerecrescens. Moreover, the dominant bacteria of Yaks were also mainly belonged to phyla firmicutes and bacteroidetes, and the known dominant bacteria were including Ruminococcus flavefaciens, Butyrivibrio fibrisolvens, Pseudobutyrivibrio ruminis, Schwartzia succinivorans and Clostridiales bacterium, most of them are common rumen bacteria. In addition, the dominant bacteria in Yunnan Yellow Cattle were belonged to phyla firmicutes, bacteroidetes and Actinobacteria, and the known dominant bacteria containing Prevotella sp., Staphylococci lentus, Staphylococcus xylosus and Corynebacterium casei. Present study first detected Staphylococcus lentus and Staphylococcus xylosus in the rumen of cattle.     

溶微囊藻细菌的富集筛选及其菌群结构特征

利用铜绿微囊藻(Microcystis aeruginosa)作为溶藻对象富集、筛选, 获得一个稳定的溶藻菌群。采用叶绿素、PCR和变性梯度凝胶电泳(DGGE)方法研究溶藻过程及其细菌种群结构的变化。结果显示, 富集的溶藻菌经1×10-5稀释后仍有显著溶藻效果。Rubritepida菌C1、假单胞菌C2和鞘氨醇单胞菌C3是存在于铜绿微囊藻中的3种伴生细菌。加入富集的溶藻菌群后, 菌群结构发生明显的变化, Rubritepida菌C1、假单胞菌C2消失, 混合菌群包含未培养黄杆菌A2、鞘氨醇单胞菌C3和噬氢     

Aquatic Francisella-like bacterium associated with mortality of intensively cultured hybrid striped bass Morone chrysops x M. saxatilis

The present study identifies an emerging disease associated with an aquatic Francisella-like bacterium that can cause mortality in hybrid striped bass Morone chrysops x M. saxatilis reared intensively in freshwater. Clinically affected fish were lethargic, had scattered haemorrhagic cutaneous lesions and diffuse gill pallor. The head kidney and spleen were markedly swollen and contained numerous interstitial granulomas; histological examination revealed small, pleomorphic Gram-negative coccobacilli within vacuolated cells. The bacterium could not be cultured from head kidney homogenates either with standard or enriched microbiological media or following inoculation of a Chinook salmon embryo (CHSE)-214 cell line. No amplification product was obtained from head kidney DNA by polymerase chain reaction (PCR) assay using Piscirickettsia salmonis-specific primers. PCR analysis of infected head kidney homogenate with primers designed for the eubacterial 16S rRNA produced a single amplicon. Phylogenetic analysis of this DNA sequence demonstrated that the sequence aligned most closely with members of the genus Francisella, identified from tilapia Oreochromis spp. in Taiwan and an aquatic Francisella species that was recently isolated from the three-line grunt Parapristipoma trilineatum in Japan. This Francisella-like disease was transmitted to naive hybrid striped bass fingerlings by intraperitoneal injection of tissue homogenates prepared from a natural outbreak. All fish developed gross and histological lesions identical to those from natural outbreaks. Intracellular Gram-negative bacteria were observed within the cytoplasm of cells (presumably macrophages) within the granulomas, but bacteria were not recovered. The 16S DNA sequence of the bacterium obtained from tissues of experimentally infected fish was identical to that obtained from the fish used as infected donor tissue.     

不同产地美花石斛内生细菌分离及促生潜力比较

对采自广西、云南和广东的美花石斛(Dendrobium loddigesii Rolfe)野生植株根、茎和叶内的内生细菌进行分离并测定其促生特性,采用扩增核糖体DNA限制性酶切分析(ARDRA)与UPGMA聚类分析相结合的方法对内生细菌菌株进行分类并确定优势属;在此基础上,对具有解磷、解钾和产生长素能力的菌株进行促生潜力评价。结果显示:从不同产地美花石斛植株不同部位共分离得到67株内生细菌菌株,其分布呈现出组织与地区的特异性;其中,来源于广西的植株中菌株数量最多(42株),分离自茎的菌株数量最多(34株)。67株内生细菌菌株可分为31个ARDRA簇,经16S rDNA序列比对鉴定为12个属,包括假单胞菌属(Pseudomonas)、微杆菌属(Microbacterium)、肠杆菌属(Enterobacter)、芽孢杆菌属(Bacillus)、鞘氨醇单胞菌属(Sphingomonas)、葡萄球菌属(Staphylococcus)、嗜冷杆菌属(Psychrobacter)、短波单胞菌属(Brevundimonas)、涅斯捷连科氏菌属(Nesterenkonia)、副球菌属(Paracoccus)、泛菌属(Pantoea)和沙雷氏菌属(Serratia),其中芽孢杆菌属、微杆菌属和肠杆菌属为优势属;来源于广西的植株中内生细菌的丰度与多样性均高于其他两地。在67株内生细菌菌株中,有30株菌株具有解无机磷和解有机磷的双重能力、22株具有解钾能力、24株具有产生长素能力,其中仅8株菌株兼具3种促生能力。组培实验结果显示:在培养基中接种1×106CFU·mL-1芽孢杆菌DLB20菌株,对株高2~3 cm和3~4 cm的美花石斛试管苗生长有促进作用,且更有利于株高3~4 cm试管苗的生根,表明具有解磷、解钾和产生长素能力的菌株对美花石斛试管苗有一定的促生潜力。     

贵州省思南县不同生境区域鼠形动物体表革螨群落对比研究

1988年对贵州省思南县不同生境区域啮齿目及食虫目动物体表革螨群落的调查结果表明:室内生境革螨种类少、多样性低、优势种突出,以毒厉螨及柏氏禽刺螨为优势种;野外生境革螨种类丰富、多样性高、优势种不突出。其中海拔较高的山区和丘陵地带野外生境革螭群落为同一类型,以毒厉螨及土尔克历螨为优势种,低海拔平坝地带为另一类型,以鼠颚毛厉螨为优势种。     

Characterization of Lactic Acid Bacteria Coexisting with a Nisin Z Producer in <Emphasis Type="Italic">Tsuda</Emphasis>-Turnip Pickles

Bacteriocin-producing lactic acid bacteria (LAB) are believed to be associated with many types of fermented food. The present study reports the identification of lactic acid bacterium MS27 producing a bacteriocin isolated from the Tsuda-turnip pickle, which is a Japanese fermented food, and characterization of LAB coexisting with the bacteriocin producers in the Tsuda-turnip pickle. The strain MS27 was identified as Lactococcus lactis subsp. lactis based on a partial 16S rRNA gene sequence and sugar fermentation pattern analyses. Mass spectroscopy and genetic analysis revealed that it produces nisin Z. Microbial population analysis revealed that the LAB community in the Tsuda-turnip pickle comprises nisin Z-sensitive and nisin Z-insensitive LAB (nonbacteriocin producers) and nisin Z producers at population rates of 52.5%, 37.5%, and 10.0%, respectively. This revealed that Leuconostoc spp. (nisin Z insensitive) is the dominant species among LAB microflora and that nisin Z insensitivity of a bacterial strain is proportional to its ability to dominate the population in Tsuda-turnip pickles. Competitive growth assay revealed that Leuconostoc spp. considerably suppressed the bacteriocin production of L. lactis MS27. These results suggested that Leuconostoc spp. contributes to the formation of the LAB community with a wide variety of microorganisms in Tsuda-turnip pickles.     

Isolation and characterization of a marine algicidal bacterium against the toxic dinoflagellate Alexandrium tamarense

Interactions between bacteria and harmful algal bloom (HAB) species have been acknowledged as an important factor regulating both the population dynamics and toxin production of these algae. A marine bacterium SP48 with algicidal activity to the toxic dinoflagellate, Alexandrium tamarense, was isolated from the Donghai Sea area, China. Genetic identification was achieved by polymerase chain reaction amplification and sequence analysis of 16S rDNA. Sequence analysis showed that the most probable affiliation of SP48 was to the γ-proteobacteria subclass and the genus Pseudoalteromonas. Bacterial isolate SP48 showed algicidal activity through an indirect attack. Additional organic nutrients but not algal-derived DOM was necessary for the synthesis of unidentified algicidal compounds but β-glucosidase was not responsible for the algicidal activity. The algicidal compounds produced by bacterium SP48 were heat tolerant, unstable in acidic condition and could be easily synthesized regardless of variation in temperature, salinity or initial pH for bacterial growth. This is the first report of a bacterium algicidal to the toxic dinoflagellate A. tamarense and the findings increase our knowledge of bacterial–algal interactions and the role of bacteria during the population dynamics of HABs.     

Enumeration of pathogenic bacteria from sewage sludge in Kuwait

Domestic sewage in Kuwait is mainly treated by an activated sludge process. Sewage sludges at different treatment stages and the digested sludge were studied for their content of pathogenic bacteria. Two Gram-positive cocci and eight Gram-negative bacilli were isolated and enumerated in the sewage sludges and in raw sewage. During March, Aeromonas hydrophila was the dominant bacterium isolated. Serratia liquefaciens in raw sewage and sludge-2, and Salmonella species in digested sludge were dominant during April. Enterobacter aerogenes was dominant in sewage samples in May. Various types of bacteria isolated were tested for their sensitivity to a wide range of antibiotics.     

Investigation on diversity and population succession dynamics of endophytic bacteria from seeds of maize (Zea mays L., Nongda108) at different growth stages

Plant seeds are carriers of both beneficial bacteria and pathogens. Using the 16S rRNA gene clone library technique, we conducted a preliminary study on the community diversity and population succession dynamics of endophytic bacteria in seeds of reciprocal cross hybrid maize at different seed developmental stages. In both hybrid lines (108A and 108B), more types of endophytic bacteria were found at the proembryo-forming stage than in the other two stages, including 29 and 23 bacterial operational taxonomic units (OTUs), respectively. Undibacterium (39.20 and 30.00 % in 108A and 108B, respectively) was the first dominant bacterium to appear. At the milky stage, fewer types of endophytic bacteria in 108A and 108B appeared, including 18 and 16 OTUs, respectively, and the abundance of the dominant genus Burkholderia in the two seed samples reached 73.38 and 80.43 %, respectively. Limnobacter appeared as the second and third endophytic dominant bacterium in 108A (4.55 %) and 108B (5.07 %), respectively, in both seed samples. At the dough stage, the abundance of the first dominant bacterium, Burkholderia, in 108A and 108B was 78.26 and 84.80 %, respectively. Pantoea appeared as the second endophytic dominant bacterium in the both seeds (9.42 and 4.80 % in 108A and 108B, respectively). This is the first study on endophytic bacteria present during several crucial stages of the dynamic grain growth process of plant seeds conducted using culture-independent methods.     

Cyanide production from glycine by a homogenate from a Pseudomonas species.

A cell-free preparation with cyanide-producing activity was obtained from a bacterium, strain C, of the genus Pseudomonas. To preserve activity, an oxidizing agent, e.g., phenazine methosulphage (PMS), had to be added to the cell suspension before disruption by sonic treatment. By the procedure described, a total homogenate made from a 15% (wet weight) bacterial suspension in tris(hydroxymethyl)aminomethane-hydrochloride buffer (0.05 M, pH 8.2) and with PMS (0.4mM) exhibited about 8% of the activity obtained from a suspension of untreated bacteria. In the presence of flavine-adenine dinucleotide (0.3 mM) and PMS (0.4mM), the activity was augmented to about 16% of that of the intact cells. By gradient centrifugation the homogenate was separated into three fractions. The main enzyme activity was associated with those fractions which by electron microscopy were found to consist of membranous structures.     

玉米青贮过程中乳酸菌动态变化

为了揭示青贮玉米在发酵过程中乳酸菌数量及种群的动态变化,以及微生物添加剂对乳酸菌种群变化的影响,采用了培养方法计数发酵过程中乳酸菌数目的变化,利用16S rRNA基因序列比对方法分析青贮玉米中乳酸菌的多样性及种群变化趋势。经过对15d时间内青贮玉米中乳酸菌变化趋势的分析显示:一周后对照组乳酸菌数最高达到2.1×106CFU/g,两处理组中处理组Ⅱ乳酸菌数达到最高5.5×107CFU/g;利用MRS平板分离、培养出典型乳酸菌菌落152株,经16S rRNA基因序列比对分析为乳杆菌属和片球菌属,其中86%的菌株属于乳杆菌属。此研究表明微生物添加剂有利于青贮玉米发酵过程中乳酸菌的快速增殖,乳杆菌属和片球菌属都是青贮玉米发酵的启动菌之一,在发酵前期一直存在,但发酵后期乳杆菌属是玉米青贮过程中乳酸菌的主要菌群。     

厦门近海海水中多环芳烃降解菌的原位富集与降解菌多样性

摘要：【目的】为了分析厦门近海原位海水中多环芳烃降解菌的多样性。【方法】将涂有菲的聚氯乙烯（PVC）板悬挂在厦门国际邮轮码头的海水中,进行菲降解菌的原位富集。利用变性梯度凝胶电泳（Denaturing gradient gel electrophoresis,DGGE）和16S rRNA基因文库两种方法分析了在PVC板表面富集微生物的菌群结构。之后,在实验室模拟原位条件下,对PVC板表面富集的菲降解菌群进行进一步富集、分离和初步鉴定。【结果】PVC板在海水中浸没6 d后,16S rRNA基因文库分析表明,在涂菲的PVC板表面富集的菌群中解环菌属（Cycloclasticus）对应的克隆子占文库总克隆子的50%;在未涂菲的PVC板表面吸附的菌群中红杆菌科（Rhodobacteraceae）为优势菌,其对应的克隆子占文库总克隆子的47%;而解环菌属的克隆子只占文库总克隆子的2%。DGGE的分析结果也证明解环菌是菲原位富集降解菌群中的优势菌。实验室进一步富集后,从该菌群中分离鉴定出14株细菌,其中一株新鞘氨醇杆菌B14(Novosphingobium sp.B14)具有菲降解能力。但是,解环菌未能获得纯培养。【结论】菲原位富集发现,厦门近海水体中解环菌是多环芳烃的主要降解菌。