Relationship of in vitro and in planta screening: improving the selection process for biological control agents against Fusarium root rot in row crops

Fusarium root rot in row crops is typically managed by cultural practices and fungicide seed treatments. Biological control using microbial agents is another option but needs further development for improved disease management. Screening to identify biocontrol agents are crucial. However, relationships among the steps and how to improve the screening process are unresolved questions. Strains of Burkholderia (4), Bacillus (5) and Trichoderma (26) were studied in vitro against six Fusarium pathogens. All the bacteria and five selected Trichoderma strains were tested in planta in the greenhouse against diseases of Fusarium graminearum and Fusarium oxysporum. Burkholderia ambifaria C628, Bacillus simplex R180, and all Trichoderma isolates showed high reduction in disease levels in corn, soybean and wheat, ranging from 16 to 63%. Responses of the biocontrol agents during in vitro and in planta screening did not always correlate. In vitro and in planta tests should be considered independently in selecting biocontrol candidates.     

高毒力昆虫病原线虫共生细菌菌株的筛选及其杀虫活性的检测

昆虫病原线虫共生细菌是寄生在昆虫病原线虫肠道的一种细菌,二者互惠共生。实验采用6个不同种的菌株为筛选材料。共生细菌菌株的培养液经85%饱和度的(NH₄)_2SO4盐析,浓缩冻干得到杀虫粗提物。以粗提物注射大蜡螟Galleria mellonella、饲喂玉米螟Ostrinia furnacalis和棉铃虫Helicoverpa armigera,发现Xenorhabdus nematophilus D43、X.bovienii A54、Photorhabdus luminescens HZL和CB-8等4个菌株发酵液的粗提物对昆虫有高的血腔毒性,菌株A54对昆虫又有高的胃毒效果。由此确立A54为高毒力的菌株,其杀虫活性表现为：注射大蜡螟48 h的死亡率为80%,96 h为93.3%;粗提物饲喂玉米螟,72 h死亡率为53.3%,120 h死亡率为100%;饲喂棉铃虫,72 h死亡率为80.1%,120 h死亡率为90%。杀虫粗提物经DEAE-52柱层析分离,得到一个穿透峰和三个盐的梯度洗脱峰,其中穿透峰对昆虫有很好的胃毒效果,但没有血腔毒性;三个盐峰均有很高的血腔毒性,但没有胃毒作用。穿透峰样品饲喂2龄、3龄棉铃虫也有很好的杀虫活性,96 h 2龄棉铃虫的死亡率为65%,3龄棉铃虫的死亡率为30%;处理96 h的棉铃虫同处理前相比体重下降,未死棉铃虫体重明显低于对照。     

Gastrointestinal parasites of the grasscutter (Thryonomys swinderianus, Temminck 1827) on the Accra Plains of Ghana

The gastrointestinal parasites of the grasscutter were investigated between 1996 and 2006 using 180 grasscutters from the Accra Plains. The aim of the study was to develop strategies for the control of the parasites under captive management. The gastrointestinal tracts of the animals were examined for the presence of both helminth and protozoan parasites with the aid of a hand lens, the direct smear and Willis Flotation techniques. In all, fourteen species of helminths were found including twelve nematodes and two cestodes. Trichuris muris was the most common nematode encountered, whilst Hepatocola hepatica was the least commonly encountered nematode. Three genera of protozoans, viz, Trichomonas spp, Giardia spp and Eimeria spp were also encountered, with Giardia spp and Trichomonas spp being reported for the first time in the grasscutter. Eimeria spp were the most prevalent protozoa. The widespread occurrence of protozoal and helminthic parasites in the grasscutter suggests that routine treatment of grasscutters with coccidiostats, anti-flagellates and anthelminthics such as dimetridazole and albendazole may contribute significantly to improve productivity of animals and reduce the pressure on wild populations.     

Kodiak®—a successful biological-control product for suppression of soil-borne plant pathogens of cotton

Cotton (Gossypium spp) has been the first large-scale, agronomic crop in the United States treated with a biological-control agent (BCA) for suppression of seedling diseases and long-term chronic diseases of the rhizosphere. The vast majority of cotton seed planted in the United States is now treated with Bacillus subtilis strain GB03, registered as Kodiak^? (Gustafson, Inc, Plano, TX, USA). Responses are typically a mixture of growth promotion (increased root mass) and disease suppression (Rhizoctonia and Fusarium spp). Strain GB03 shows exceptional rhizosphere competence, colonizing the rhizosphere of monocots and dicots. Though the initial success of strain GB03 has been observed in the production of cotton, other crops have shown positive yield responses following bacterization. Since B. subtilis is a spore-forming organism, it is extremely tolerant of environmental stresses, including seed-treatment pesticides, soil and seed pH, cultivar effects, edaphic factors and long-term storage. More importantly, it is readily produced with current fermentation technology. Other BCAs, such as Pseudomonas spp, do not readily adapt to large-scale production methods, and stability is a limiting factor. In order to be successful, scale-up production must provide a product with efficacy equivalent to the laboratory model. A better understanding of how fermentation and other production processes affect the efficacy and rhizosphere competence of biocontrol organisms is now required by the industry. Processes have to be carefully optimized for both maximum production and maximum efficacy. A strong collaboration and understanding between the agricultural industry and industrial microbiologists are required to continue the advance of new biologicals such as Kodiak^?. Received 06 February 1997/ Accepted in revised form 16 April 1997     

Identification of an Apically-Located Antigen That Is Conserved in Sporozoan Parasites

ABSTRACT. Sporozoan parasites of the phylum Apicomplexa all possess common apical structures. The current study used a monoclonal antibody (mAb-E12) to identify a conserved antigen in the apical region of merozoites of seven species of Plasmodium (including rodent, primate and human pathogens), tachyzoites of Toxoplasma gondii , bradyzoites of Sarcocystis bovis , and sporozoites and merozoites of Eimeria tenella and E. acervulina. The antigen was also present in sporozoites of haemosporinid parasites. Immunofluorescence studies showed that the antigen was restricted to the apical 3rd of these invasive stages. Using immunoelectron microscopy, labeling was demonstrated in the region of the polar ring, below the paired inner membranes of the parasite pellicle, and near the subpellicular microtubules radiating from the polar ring of merozoites and sporozoites of E. tenella . The majority of the antigen could be extracted with 1% Triton-X 100, but a portion remained associated with the cytoskeletal elements. The molecule has a relative rate of migration (M_r) of 47,000 in Plasmodium spp. and 43–46,000 in coccidian species. Since the epitope recognized by mAb-El 2 is highly conserved, restricted to motile stages, and appears to be associated with microtubules, this antigen could be involved in cellular motility and cellular invasion.     

Survival of several <Emphasis Type="Italic">Rhizobium/Bradyrhizobium</Emphasis> strains on different inoculant formulations and inoculated seeds

The effect of a variety factors on the survival of several rhizobia strains on inoculants and inoculated seeds has been evaluated. Since the rhizobia strains showed different cell-density-evolution patterns on peat-based inoculants and on inoculated seeds, several inoculant formulations with highly effective Rhizobium/Bradyrhizobium strains (for Lupinus, Hedysarum, Phaseolus and Glycine max.) were monitored under the following storage conditions: (a) the inoculants were kept refrigerated (at 4 °C), or (b) at room temperature (25 °C). The effect of water content (30–50%, w/w) in the inoculants as well as that of several seed-coating adhesives were also investigated. Alternative carriers including perlite and vermiculite were tested. For all of the strains, survival on sterile peat-based inoculants was higher than on the corresponding unsterile peat formulation; for the latter, refrigerated storage conditions are recommended to ensure high bacterial densities. The water content of the inoculants had a differential effect on strain survival depending on the sterility of the peat, such that a high water content was more detrimental when unsterilized peat was employed. The best adherent for rhizobia survival was a gum arabic/water solution. Perlite was as effective as peat in maintaining a high population of rhizobia, at least for 6 months of storage. Electronic Publication     

Occurrence of Acremonium endophytes in wild populations of Lolium spp. in European countries and a relationship between level of infection and climate in France

Infection with endophytic fungi (Acremonium spp.) was detected in wild populations of Lolium spp. from 15 of 20 European countries. Of 523 populations examined, 38% contained no infection, 48% contained 1–50% infection and 14% contained 51–100% infection. Level of infection was slightly but significantly associated with abundance of Lolium in the sward. For data from France, significant correlations were obtained between level of infection and five climate variables; the highest correlations were with evapotranspiration (0.66, P < 0.001) and water supply deficit (-0.66, P < 0.001). A model established using multiple regression analysis and incorporating five climatic variables, accounted for 56% of total variation; water supply deficit alone accounted for 43%. These climatic variables were shown by geostatistical analysis to account for a spatial structure in infection level. Groups of Lolium populations with a high level of infection were located mostly in Mediterranean regions, where stress from summer drought is common.     

禾本科植物内生真菌研究5. 中国产部分epichlo?内生真菌的遗传多样性

Epichlo?内生真菌（epichlo? endophytes）是禾本科植物的共生真菌,开展其多样性研究对菌株的生物学特性和进化规律的了解以及开发利用都有着十分重要的意义。本研究筛选了12条随机引物对24株epichlo?内生真菌进行RAPD扩增,探讨真菌种类、宿主种类、采集地和菌株间的遗传多样性。结果表明,宿主为拂子茅Calamagrostis sp.、雀麦Bromus sp.、披碱草Elymus sp.、小颖羊茅Festuca parvigluma Steud.的菌株分别独立聚为一个分枝;而宿主为鹅观草Roegneria spp.的Neotyphodium属菌株聚类情况较为复杂;宿主为早熟禾Poa spp.的菌株分别在三个不同的分枝,表现出丰富的遗传多样性。以上结果反应了我国具有丰富的epichlo?内生真菌资源,它们和其宿主之间有着比较明显的相互关系。本研究还显示,采集于南京的拂子茅与其内生真菌共生可能发生在较久远的年代。     

Prevalence of keds on city dogs in central Poland

The aim of this study was to identify the species of ked infesting dogs in the cities of central Poland. A total of 510 dogs were observed between June and September 2015. The presence of keds was noted in 182 (35.7%) animals. Keds were more prevalent in female (38.0%) than in male (33.2%) dogs, and were more frequently found in animals younger than 1 year (46.2%) and in long‐haired dogs (36.6%). The body areas most heavily colonized by keds were the groin (35.4%) and neck (21.4%). A total of 904 keds were isolated from dogs, including Hippobosca equina (Diptera: Hippoboscidae) (17.2%), Lipoptena cervi (Diptera: Hippoboscidae) (32.0%), and two species not previously encountered in Poland: Hippobosca longipennis (45.0%) and Lipoptena fortisetosa (5.9%). Hippoboscidae may act as vectors of pathogens and any shifts in their geographic range may lead to the spread of new diseases affecting animals.     

昆虫病原线虫共生菌杀虫毒素研究进展

对昆虫病原线虫共生菌杀虫毒素的种类、与口服毒性有关的杀虫毒素以及口服毒性与杀虫毒素基因的关系等研究进展进行了综述,并对未来的研究方向提出了作者的见解。     

禾本科植物内生真菌研究 5.中国产部分epichloё内生真菌的遗传多样性

Epichloё内生真菌(epichloё endophytes)是禾本科植物的共生真菌,开展其多样性研究对菌株的生物学特性和进化规律的了解以及开发利用都有着十分重要的意义。本研究筛选了12条随机引物对24株epichloё内生真菌进行RAPD扩增,探讨真菌种类、宿主种类、采集地和菌株间的遗传多样性。结果表明,宿主为拂子茅Calamagrostis sp.、雀麦Bromus sp.、披碱草Elymus sp.、小颖羊茅Festuca parvigluma Steud.的菌株分别独立聚为一个分枝;而宿主为鹅观草Roegneria spp.的Neotyphodium属菌株聚类情况较为复杂;宿主为早熟禾Poas pp.的菌株分别在三个不同的分枝,表现出丰富的遗传多样性。以上结果反应了我国具有丰富的epichloё内生真菌资源,它们和其宿主之间有着比较明显的相互关系。本研究还显示,采集于南京的拂子茅与其内生真菌共生可能发生在较久远的年代。     

Resistance to cyst nematode (Heterodera cajani) in pigeonpea cultivars and in wild relatives of Cajanus*

Heterodera cajani is an important nematode pest of pigeonpea in India. Evaluation of 58 pigeonpea cultivars and 61 accessions of Cajanus acutifolius, C. cajanifolius, C. grandifolius, C. lanceolatus, C. lineatus, C. mollis, C. pla-tycarpus, C. reticulatus, C. scarabaeoides, C. sericeus, C. volubilis, Flemingia macrophylla, F. stricta, F. strobilifera, Rhynchosia aurea, R. bracteata, R. cana, R. densiflora, R. minima, R. rothii, R. suaveolens and R. sublobata revealed that the tested pigeonpea cultivars lacked resistance to H. cajani. Eight accessions of wild relatives were resistant and 20 accessions were moderately resistant. Based on the white cyst number on roots and low plant-to-plant variation, two accessions of C. scarabaeoides (ICPWs 111 and 128), three accessions of Flemingia spp. (ICPWs 194, 202 and 203), and one accession each of R. rothii (ICPW 257), R. densiflora (ICPW 224), and R. aurea (ICPW 210) were identified as resistant and promising for use in intergeneric hybridisation programmes.     

The use of probiotics in shrimp aquaculture

Shrimp aquaculture, as well as other industries, constantly requires new techniques in order to increase production yield. Modern technologies and other sciences such as biotechnology and microbiology are important tools that could lead to a higher quality and greater quantity of products. Feeding and new practices in farming usually play an important role in aquaculture, and the addition of various additives to a balanced feed formula to achieve better growth is a common practice of many fish and shrimp feed manufacturers and farmers. Probiotics, as 'bio-friendly agents' such as lactic acid bacteria and Bacillus spp., can be introduced into the culture environment to control and compete with pathogenic bacteria as well as to promote the growth of the cultured organisms. In addition, probiotics are nonpathogenic and nontoxic microorganisms without undesirable side-effects when administered to aquatic organisms. These strains of bacteria have many other positive effects, which are described in this article.     

Keratinophilic fungi associated with starlings Sturnus vulgaris in Brittany,France

The occurrence of keratinophilic fungi on the feathers of 110 starlings (Sturnus vulgaris) was investigated in order to assess the part that these birds may have in spreading of fungi of medical interest. Thirty eight birds (26%) yielded keratinophilic fungi, primarily Chrysosporium species, but also Scopulariopsis brevicaulis and Trichophyton terrestre. We reviewed the pathogenicity of the isolated fungi. Starlings may spread the propagules of keratinophilic fungi but it is difficult to determine if their increasing numbers in cities can be of significance in the epidemiology of today's rare mycoses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Yersiniabactin and other siderophores produced by clinical isolates of Enterobacter spp. and Citrobacter spp

We analyzed the ability of extraintestinal strains of Enterobacter spp. and Citrobacter spp. to employ different siderophore-mediated strategies of iron acquisition. All strains produced iron-chelating compounds. Cross-feeding assays indicated that most isolates of both Enterobacter spp. and Citrobacter spp. excreted catecholate siderophore enterobactin, less produced aerobactin, and single strains excreted hydroxamates different from aerobactin. Besides, we analyzed if the strains had the ability to produce the siderophore yersiniabactin coded by the Yersinia high-pathogenicity island (HPI). The presence of HPI genes was observed in single isolates of three species: E. cloaceae, E. aerogenes and C. koseri. A detailed polymerase chain reaction analysis revealed differences in the genetic organization of the HPIs; however, in a cross-feeding test we proved that yersiniabactin was produced and the island was functional.     

1-Kestose consumption during pregnancy and lactation increases the levels of IgA in the milk of lactating mice

To examine the effect of dietary supplementation with 1-kestose on the IgA levels in milk, BALB/c mice were fed diets with or without 5% 1-kestose during pregnancy and lactation. The total and specific IgA levels in the milk were measured at 7 and 14?days after delivery. A two-way ANOVA with repeated measures resulted in a significant effect of 1-kestose-supplementation on total IgA concentrations (p?<?0.05) and the level of anti-Bacteroides IgA (p?<?0.05). A significant positive correlation was found between the mean count of Bacteroides spp. in maternal feces and the total IgA concentration in maternal milk (r?=?0.55, p?<?0.05), suggesting a potential link between the gut and mammary gland immune system. In conclusion, this study demonstrated the effects of dietary prebiotics on milk IgA production.