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Staffan Kjelleberg - One of the best experts on this subject based on the ideXlab platform.

  • Antidiatom and antiBacterial activity of Epiphytic Bacteria isolated from Ulva lactuca in tropical waters
    World Journal of Microbiology and Biotechnology, 2011
    Co-Authors: V. Kumar, Staffan Kjelleberg, D. Rao, T. Thomas, S. Egan
    Abstract:

    Bacteria and diatoms are primary colonizers of marine surfaces and hence play a crucial role in the attachment and subsequent growth of macroorganisms. It has been suggested that the temperate green alga Ulva lactuca relies on the defence provided by the Epiphytic Bacterial community to regulate surface fouling of colonising organisms. In this study, ten resident Bacterial isolates from tropical U . lactuca were tested for their antiBacterial and antidiatom properties that may regulate surface colonization on the algae. Sixty percent of the Epiphytic isolates expressed antiBacterial properties against other resident Bacteria and 80% had antidiatom activity against the pennate diatom, Cylindrotheca fusiformis . Isolates of the Pseudoalteromonas genus showed both- antiBacterial and antidiatom activities, while members of the genus Bacillus , Vibrio and Shewanella mostly possessed antidiatom activity. Our results show that a high proportion of Bacterial isolates from tropical U . lactuca , like that of their temperate counterparts contain antibiotic properties that might impact on the Bacterial community composition and prevent fouling by diatoms.

  • Antimicrobial activity observed among cultured marine Epiphytic Bacteria reflects their potential as a source of new drugs
    FEMS Microbiology Ecology, 2009
    Co-Authors: Anahit Penesyan, Carola Holmström, Staffan Kjelleberg, Zoe Marshall-jones, Suhelen Egan
    Abstract:

    The surfaces of marine eukaryotes provide a unique habitat for colonizing microorganisms where competition between members of these communities and chemically mediated interactions with their host are thought to influence both microbial diversity and function. For example, it is believed that marine eukaryotes may use their surface-associated Bacteria to produce bioactive compounds in defence against competition and to protect the host against further colonization. With the increasing need for novel drug discovery, marine epibiotic Bacteria may thus represent a largely underexplored source of new antimicrobial compounds. In the current study, 325 Bacterial isolates were obtained from the surfaces of marine algae Delisea pulchra and Ulva australis. Thirty-nine showed to have antimicrobial activity and were identified via 16S rRNA gene sequencing. The majority of those isolates belonged to Alpha- and GammaproteoBacteria. Interestingly, the most commonly isolated Bacterial strain, Microbulbifer sp., from the surface of D. pulchra has previously been described as an ecologically significant epibiont of different marine eukaryotes. Other antimicrobial isolates obtained in this study belonged to the phyla ActinoBacteria, Firmicutes and Bacteroidetes. Phylogenetically, little overlap was observed among the Bacteria obtained from surfaces of D. pulchra and U. australis. The high abundance of cultured isolates that produce antimicrobials suggest that culturing remains a powerful resource for exploring novel bioactives of Bacterial origin.

  • Antimicrobial activityobservedamong culturedmarine Epiphytic Bacteria re£ects their potential as a source of newdrugs
    2009
    Co-Authors: Anahit Penesyan, Suhelen Egan, Staffan Kjelleberg, Carola Holmström, Zoe Marshall-jones, Correspondence Staffan Kjelleberg, Of Biotechnology, Biomolecular Sciences
    Abstract:

    diversity. The surfaces of marine eukaryotes provide a unique habitat for colonizing microorganisms where competition between members of these communities and chemically mediated interactions with their host are thought to influence both microbial diversity and function. For example, it is believed that marine eukaryotes may use their surface-associated Bacteria to produce bioactive compounds in defence against competition and to protect the host against further colonization. With the increasing need for novel drug discovery, marine epibiotic Bacteria may thus represent a largely underexplored source of new antimicrobial compounds. In the current study, 325 Bacterial isolates were obtained from the surfaces of marine algae Delisea pulchra and Ulva australis. Thirty-nine showed to have antimicrobial activity and were identified via 16S rRNA gene sequencing. The majority of those isolates belonged to Alpha- and GammaproteoBacteria. Interestingly, the most commonly isolated Bacterial strain, Microbulbifer sp., from the surface of D

  • low densities of Epiphytic Bacteria from the marine alga ulva australis inhibit settlement of fouling organisms
    Applied and Environmental Microbiology, 2007
    Co-Authors: Jeremy S Webb, Carola Holmström, Rebecca J Case, Peter D Steinberg, Staffan Kjelleberg
    Abstract:

    Bacteria that produce inhibitory compounds on the surface of marine algae are thought to contribute to the defense of the host plant against colonization of fouling organisms. However, the number of Bacterial cells necessary to defend against fouling on the plant surface is not known. Pseudoalteromonas tunicata and Phaeobacter sp. strain 2.10 (formerly Roseobacter gallaeciensis) are marine Bacteria often found in association with the alga Ulva australis and produce a range of extracellular inhibitory compounds against common fouling organisms. P. tunicata and Phaeobacter sp. strain 2.10 biofilms with cell densities ranging from 102 to 108 cells cm–2 were established on polystyrene petri dishes. Attachment and settlement assays were performed with marine fungi (uncharacterized isolates from U. australis), marine Bacteria (Pseudoalteromonas gracilis, Alteromonas sp., and Cellulophaga fucicola), invertebrate larvae (Bugula neritina), and algal spores (Polysiphonia sp.) and gametes (U. australis). Remarkably low cell densities (102 to 103 cells cm–2) of P. tunicata were effective in preventing settlement of algal spores and marine fungi in petri dishes. P. tunicata also prevented settlement of invertebrate larvae at densities of 104 to 105 cells cm–2. Similarly, low cell densities (103 to 104cells cm–2) of Phaeobacter sp. strain 2.10 had antilarval and antiBacterial activity. Previously, it has been shown that abundance of P. tunicata on marine eukaryotic hosts is low (<1 x 103 cells cm–2) (T. L. Skovhus et al., Appl. Environ. Microbiol. 70:2373-2382, 2004). Despite such low numbers of P. tunicata on U. australis in situ, our data suggest that P. tunicata and Phaeobacter sp. strain 2.10 are present in sufficient quantities on the plant to inhibit fouling organisms. This strongly supports the hypothesis that P. tunicata and Phaeobacter sp. strain 2.10 can play a role in defense against fouling on U. australis at cell densities that commonly occur in situ

  • A CARD-FISH protocol for the identification and enumeration of Epiphytic Bacteria on marine algae.
    Journal of Microbiological Methods, 2006
    Co-Authors: Niina Tujula, Staffan Kjelleberg, Carola Holmström, Marc Mussmann, Rudolf Amann, Gregory Crocetti
    Abstract:

    Abstract A CARD–FISH protocol was developed and applied to analyse surface-associated Bacteria on the marine algae Ulva lactuca , Delisea pulchra , Corallina officinalis , Amphiroa anceps , Porphyra sp. and Sargassum linearifolium . The combination of Alexa 546 -labelled tyramide as the reporter molecule with SYBR Green II counterstain allowed for superior detection of the hybridised probe fluorescence against plant tissue from which pigment autofluorescence has been reduced.

Raymond Goulder - One of the best experts on this subject based on the ideXlab platform.

  • increase in Epiphytic Bacteria downstream of a sewage works outfall monitoring using artificial hydrophytes
    Bulletin of Environmental Contamination and Toxicology, 1997
    Co-Authors: J Y Kang, Raymond Goulder
    Abstract:

    Epiphytic Bacteria on submerged freshwater quantified by direct microscopic counting of aniline-blue stained, Bacteria (Hossell and macrophytes may be in situ, phenolicBaker 1979). Thus, Kang and Goulder (1996) used in situ counting to demonstrate increased abundance of Bacteria, per unit leaf area, on water starwort, Callitriche L. sp., and Canadian pondweed, Elodea canadensis Michx., downstream of sewage works outfalls. Such increases in Epiphytic Bacteria are potentially important in promoting biopurification of organically-enriched river waters. In situ counting is, however, very labor-intensive. An alternative, more economic, approach to the quantification of Epiphytic Bacteria is the preparation of a suspension of epiphyton by treatment of the host plant in a stomacher, followed by direct counting of Bacteria in the suspension by epifluorescence microscopy (Rimes and Goulder 1986). The plant material is dried and weighed after stomaching, and results are expressed as Bacteria per unit dry weight of host macrophyte. Interpretation of results is, however, complicated by the fact of substantial within-species and between-species variation in the surface area:dry weight ratio of submerged macrophytes (Fry and Humphrey 1978). This complication might potentially be overcome by the use of artificial plants which have uniform surface area, and hence readily allow determination of abundance on an areal basis. In the work described here, we investigated the effect of a sewage works outfall on density of Epiphytic Bacteria, assayed by direct epifluorescence counting of Bacteria in epiphyte suspensions produced by stomaching of both real plants (Callitriche and E. canadensis) and artificial plants. Since pennate diatoms, principally Cocconeis Ehr. sp., were also a substantial component of the epiphyton, these too were counted on the artificial plants.

  • Epiphytic Bacteria downstream of sewage works outfalls
    Water Research, 1996
    Co-Authors: J Y Kang, Raymond Goulder
    Abstract:

    Abstract Epiphytic microorganisms were investigated in two watercourses which were enriched by sewage-works effluent. These were a disused canal and a small stream in North-East England. Scanning electron microscopy, on the submerged macrophytes Callitriche sp. and Elodea canadensis, from the canal, demonstrated abundant epiphyton which was dominated by rod-shaped Bacteria and pennate diatoms, especially Cocconeis sp. An in situ counting technique showed that the density of Epiphytic Bacteria was greater downstream of the sewage-works outfall on plants from both watercourses. The proportion of metabolically-active Epiphytic Bacteria, and cell length of Epiphytic Bacteria, were determined on Callitriche in the small stream, and were greater downstream of the outfall. Thus increase in (1) the population density of Epiphytic Bacteria, (2) the proportion of cells which were metabolically active, and (3) cell size, combined to increase the potential contribution of Epiphytic Bacteria to biopurification and downstream recovery. Epiphytic diatoms, in contrast to Bacteria, apparently did not increase in abundance downstream of the outfalls.

Steven E Lindow - One of the best experts on this subject based on the ideXlab platform.

  • high level culturability of Epiphytic Bacteria and frequency of biosurfactant producers on leaves
    Applied and Environmental Microbiology, 2016
    Co-Authors: Adrien Y Burch, Adrian Sbodio, Trevor V Suslow, Steven E Lindow
    Abstract:

    ABSTRACT To better characterize the Bacterial community members capable of biosurfactant production on leaves, we distinguished culturable biosurfactant-producing Bacteria from nonproducers and used community sequencing to compare the composition of these distinct cultured populations with that from DNA directly recovered from leaves. Communities on spinach, romaine, and head lettuce leaves were compared with communities from adjacent samples of soil and irrigation source water. Soil communities were poorly described by culturing, with recovery of cultured representatives from only 21% of the prevalent operational taxonomic units (OTUs) (>0.2% reads) identified. The dominant biosurfactant producers cultured from soil included bacilli and pseudomonads. In contrast, the cultured communities from leaves are highly representative of the culture-independent communities, with over 85% of the prevalent OTUs recovered. The dominant taxa of surfactant producers from leaves were pseudomonads as well as members of the infrequently studied genus Chryseobacterium. The proportions of Bacteria cultured from head lettuce and romaine leaves that produce biosurfactants were directly correlated with the culture-independent proportion of pseudomonads in a given sample, whereas spinach harbored a wider diversity of biosurfactant producers. A subset of the culturable Bacteria in irrigation water also became enriched on romaine leaves that were irrigated overhead. Although our study was designed to identify surfactant producers on plants, we also provide evidence that most Bacteria in some habitats, such as agronomic plant surfaces, are culturable, and these communities can be readily investigated and described by more classical culturing methods. IMPORTANCE The importance of biosurfactant production to the Bacteria that live on waxy leaf surfaces as well as their ability to be accurately assessed using culture-based methodologies was determined by interrogating Epiphytic populations by both culture-dependent and culture-independent methods. Biosurfactant production was much more frequently observed in cultured communities on leaves than in other nearby habitats, such as soil and water, suggesting that this trait is important to life on a leaf by altering either the leaf itself or the interaction of Bacteria with water. While pseudomonads were the most common biosurfactant producers isolated, this habitat also selects for taxa, such as Chryseobacterium, for which this trait was previously unrecognized. The finding that most Epiphytic Bacterial taxa were culturable validates strategies using more classical culturing methodologies for their study in this habitat.

  • acyl homoserine lactone mediated cross talk among Epiphytic Bacteria modulates behavior of pseudomonas syringae on leaves
    The ISME Journal, 2009
    Co-Authors: Glenn F J Dulla, Steven E Lindow
    Abstract:

    The leaf surface harbors a host of Bacterial epiphytes that are capable of influencing the quorum sensing (QS) system of the plant pathogen Pseudomonas syringae pv. syringae (Pss). Pss uses QS to regulate expression of genes conferring extracellular polysaccharide production, motility and factors contributing to virulence to plants. About 7% of Bacterial epiphytes isolated in this study produce the Pss cognate signal, 3-oxohexanoyl-homoserine lactone (3OC6HSL), often in amounts more than 10-fold higher than Pss. Premature induction of QS in Pss by these 3OC6HSL-producing epiphytes suppressed swarming motility and subsequent disease of the leaf. Co-inoculation of 3OC6HSL-producing strains with Pss reduced the number of lesions when inoculated together onto leaves compared with that of plants inoculated with Pss alone. Strains in which 3OC6HSL accumulation was quenched by expression of an N-acyl-homoserine lactonase did not decrease disease when co-inoculated with Pss. Disease incidence caused by a nonmotile mutant of Pss was not affected by 3OC6HSL-producing Bacteria, suggesting that exogenous 3OC6HSL signal that altered the motility of Pss was responsible for reducing the apparent virulence of this pathogen. Thus, considerable cross talk involving exogenous 3OC6HSL occurs on leaves and this process can be exploited for disease control.

  • occurrence of indole 3 acetic acid producing Bacteria on pear trees and their association with fruit russet
    Phytopathology, 1998
    Co-Authors: Steven E Lindow, Caroline Desurmont, Rachel Elkins, Glenn Mcgourty, Ellen Clark, Maria T Brandl
    Abstract:

    ABSTRACT A relatively high percentage of Epiphytic Bacteria on pear leaf and fruit surfaces had the ability to produce indole-3-acetic acid (IAA) in culture media supplemented with tryptophan. While over 50% of the strains produced at least small amounts of IAA in culture, about 25% of the strains exhibited high IAA production as evidenced by both colorimetric and high-performance liquid chromatography analysis of culture supernatants. A majority of the strains that produced high amounts of IAA were identified as Erwinia herbicola (Pantoea agglomerans), while some strains of Pseudomonas syringae, Pseudomonas viridiflava, Pseudomonas fluorescens, Pseudomonas putida, and Rahnella aquaticus that produced high amounts of IAA also were found on pear. Fruit russeting was significantly increased in 39 out of 46 trials over an 8-year period in which IAA-producing Bacteria were applied to trees compared with control trees. A linear relationship was observed between fruit russet severity and the logarithm of the po...

  • determinants of Epiphytic fitness in Bacteria
    1991
    Co-Authors: Steven E Lindow
    Abstract:

    The Bacteria that inhabit the phylloplane are generally distinctive from those that colonize other habitats and therefore probably have special adaptations which allow them to exploit leaf surfaces. Several studies have noted that a majority of the Bacteria isolated from leaf surfaces are pigmented, unlike those recovered from other habitats such as nearby soil (Stout, 1960a, 1960b; Goodfellow and Austin, 1976). It has been speculated (Gibbins and Peterson, 1978) that pigmentation in Epiphytic Bacteria is an adaptation which allows these microorganisms to tolerate incident ultraviolet (UV) light impinging on the leaf surface (Dickinson, 1986). Presumably, such adaptations would be unnecessary in Bacteria inhabiting other habitats in which incident UV radiation was lower.

R May - One of the best experts on this subject based on the ideXlab platform.

  • biological control of pseudomonas syringae pv glycinea by Epiphytic Bacteria under field conditions
    Microbial Ecology, 2001
    Co-Authors: Beate Volksch, R May
    Abstract:

    The efficacy of a Bacterial strain as a biocontrol agent in the field may be related to the ecological similarity between the biocontrol agent and the target pathogen. Therefore, a number of different Pseudomonas syringae strains were evaluated for their antagonistic activities in vitro (agar-diffusion assay) and in planta (greenhouse assay) against the target pathogen, Pseudomonas syringae pv. glycinea. Six strains of five different pathovars were found to be antagonistic in vitro as well as in planta. The Epiphytic fitness of the antagonistic Pseudomonas syringae strain 22d/93 and its two antibiotic-resistant mutants were examined on soybean plants in the fields. After adaptation the parental strain and its mutants had the ability to establish and maintain large Epiphytic populations (about 106 cfu/g FW) over the whole growing season after a single spray inoculation. The Epiphytic behaviors of the mutants and the parent were not significantly different. The introduced Bacteria did not influence the total Bacterial population size. When the antagonist was coinoculated with the pathogen, the development of the pathogen was significantly reduced during the whole growing season. When the antagonistic strain was inoculated 4 weeks in advance of the pathogen, this antagonistic effect could be markedly enhanced. The final population size of the pathogen reached just 104 cfu/g FW and was significantly reduced to 0.12% compared to the pathogen alone. This study demonstrates that biological control of foliar pathogens through colonization of the host plants with near isogenic or ecologically similar antagonistical strains seems to be a realistic goal.

  • characterization of two Epiphytic Bacteria from soybean leaves with antagonistic activities against pseudomonas syringae pv glycinea
    Journal of Basic Microbiology, 1996
    Co-Authors: Beate Volksch, Jorg Nuske, R May
    Abstract:

    The strains 48b/90 and 22d/93 are naturally occurring ephiphytes which were isolated from soybean leaves. On the basis of pheno- and genotypic characteristics 48b/90 was identified as Erwinia herbicola and 22d/93 as Pseudomonas syringae. These two isolates produced biological active substances against different indicator organisms. The E. herbicola strain showed clear antagonistic properties against Escherichia coli and Pseudomonas syringae pv. glycinea, but not against Geotrichum candidum. 22d/93 was active against P. glycinea and G. candidum, but not against E. coli. Strain 48b/90 produced at least two different inhibitors: an antibiotic substance and an inhibitor of the alginate synthesis. Strain 22d/93 produced at least three different compounds inhibitory to P. glycinea and one to G. candidum. Their activities against the Bacterial blight pathogen, P. glycinea, can be observed in planta, too. Under the influences of the antagonists the pathogen multiplied at lower rates and to lower stationary phase population levels. The development of Bacterial blight symptoms was suppressed.

Robert E Mandrell - One of the best experts on this subject based on the ideXlab platform.

  • escherichia coli o157 h7 survival and growth on lettuce is altered by the presence of Epiphytic Bacteria
    Journal of Food Protection, 2006
    Co-Authors: Michael B Cooley, Diana Chao, Robert E Mandrell
    Abstract:

    Escherichia coli O157:H7 can survive in low numbers in soil and on plants. Occasionally, conditions may occur in the field that lead to contamination of produce. Survival of enteric pathogens in the field is controlled to a certain extent by complex interactions with indigenous soilborne and seedborne epiphytes. Identifying these interactions may assist in developing strategies to improve produce safety. Two epiphytes were isolated from pathogen-contaminated plants that interact differently with E. coli O157:H7. Wausteria paucula enhanced the survival of E. coli O157:H7 six-fold on lettuce foliage grown from coinoculated lettuce seed. In contrast, Enterobacter asburiae decreased E. coli O157:H7 survival 20- to 30-fold on foliage. Competition also occurred in the rhizosphere and in plant exudate. This competition may be the result of E. asburiae utilization of several of the carbon and nitrogen substrates typically present in exudate and also used by E. coli O157:H7. Hence, competition observed on the plan...