Filamentous Bacteria

3 Key excerpts on "Filamentous Bacteria"

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  eBook - ePub

  Biofilms in Plant and Soil Health

  • Iqbal Ahmad, Fohad Mabood Husain, Iqbal Ahmad, Fohad Mabood Husain(Authors)
  • 2017(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  Microbiologists have documented that microbial populations in their natural environments form biofilms—complex communities attached to surfaces in a self-produced polymeric matrix [3–6]. The study of microbial biofilms has led to a shift in our understanding of how microorganisms grow, survive, adapt, and exploit hosts and resources. The bulk of biofilm research has been done on bacteria in aquatic or clinical settings, and a few examples on plants [7–9]. Fungal biofilms have also been studied, mainly in model yeast pathogens responsible for human and animal diseases [10–14]. Only recently have reports of filamentous fungal biofilms been gradually accumulating. The focus of this chapter is to review and integrate what is known about filamentous fungal biofilms with special attention to those formed on or within plant tissues or in soils.

  8.2 What Is a Biofilm?

  The linguistic meaning of the word biofilm literally translates to “biological material in a thin layer, ” but the more we learn about biofilms, the more difficult it is for all to agree on a single definition [15, 16]. A definition for filamentous biofilms becomes additionally challenging because of the unique morphology and tip growth of hyphal filaments when compared to the single-celled populations of bacteria or yeasts undergoing binary fission or budding. Filamentous fungi cannot always be cultured, measured, manipulated, or enumerated using the same experimental protocols as those used for the individual cells within bacteria and yeast biofilms. As a result, methods for describing and quantifying filamentous fungal biofilms are quite different from those established for bacteria and budding yeasts. Despite these challenges, it is important to define the term biofilm for the purposes of this chapter such that it is inclusive to bacteria, yeast, and filamentous microorganisms growing in natural environments or under laboratory conditions. Herein, we use biofilm

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  eBook - ePub

  Water Purification

  • Alexandru Grumezescu(Author)
  • 2016(Publication Date)
  • Academic Press

    (Publisher)

  Husham et al., 2012 ). The purpose of this chapter is to present the characteristics of microbial biofilms found in the aquatic ecosystems with a special focus on their both negative and beneficial roles for the water treatment and quality.

  2. Definition of Biofilm

  Biofilm represents a structured microbial community adherent to an inert or living surface embedded in a self-secreted polymeric matrix (Zarnea and Popescu, 2011 ). It has a heterogeneous structure, the cells embedded in this matrix exhibiting a modified phenotype, especially concerning the growth rate and gene transcription, and a mono- or, the most often, a multispecific composition, regulated by multiple signaling mechanisms dependent on the cellular density, known as quorum sensing and response (QS) systems (Costerton, 2009 ; Donlan, 2002 ; Lazãr and Chifiriuc, 2010a ). In QS, the communication between the cellular components of a biofilm is achieved by chemical signal micromolecules with different structures represented by peptides in Gram-positive bacteria and l -homoserin-lactones in Gram-negative species (Davey and O’Toole, 2000 ; Davies et al., 1993 ;  1998 ; Chifiriuc et al., 2014 ). The QS regulation mechanism is involved in various physiological processes (biofilm formation, antibiotic production, bioluminescence, genetic competence, sporulation, swarming motility), as well as in the expression of virulence potential (Lazãr and Chifiriuc, 2010b ). It has been shown that the QS-mutant strains have a decreased potential to develop mature biofilms, forming only thin and uniform structures (Delden and Iglewski, 1998 ). When the signaling molecules reach a threshold concentration which reflects a certain density of the microbial cells inside biofilm, the gene expression of 40–60% of the bacterial genome is changed having a consequence that the modification of biofilm cells phenotype in comparison with that of their planktonic counterparts (Israil and Chifiriuc, 2009

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  eBook - ePub

  New and Future Developments in Microbial Biotechnology and Bioengineering: Microbial Biofilms

  Current Research and Future Trends in Microbial Biofilms

  • Mukesh Kumar Yadav, Bhim Pratap Singh(Authors)
  • 2019(Publication Date)
  • Elsevier

    (Publisher)

  Chapter 16

  Agriculturally important microbial biofilms: Biodiversity, ecological significances, and biotechnological applications

  Kusam Lata Ranaa ; Divjot Koura ; Ajar Nath Yadava ; Neelam Yadavb ; Anil Kumar Saxenac     

  a Department of Biotechnology, Akal College of Agriculture, Eternal University, Baru Sahib, India

  b Gopi Nath P.G. College, Veer Bahadur Singh Purvanchal University, Jaunpur, India

  c ICAR-National Bureau of Agriculturally Important Microorganisms, Kusmaur, India

  Abstract

  A biofilm is an assemblage, aggregation, or community of microbial cells bounded by a polymeric matrix comprising polysaccharides that are associated with an inert or biotic surface. Biofilm formation is a universal trait, exhibited by microbes, when growing attached to natural and artificial surfaces. Microbial biofilms are an attractive subject, due to their important roles in the different sectors including agriculture, environment, industry, and health. Biofilms in agriculture have acquired interest due to their immense possibilities in crop production, protection, and improvement through their role in colonization of surface soils, roots/shoots of plants, and enabling proliferation in the desired niche, as well as enhancing soil fertility. Biofilm-forming microbes have been reported worldwide and they belong to Gram-positive, Gram-negative species, cyanobacteria, archaea, fungi, and microalgae. The microbial biofilm formation has been reported by all three domain systems of archaea, bacteria, and eukarya of different phylum including Actinobacteria, Ascomycota, Bacteroidetes, Basidiomycota, Chloroflexi, Crenarchaeota, Cyanobacteria, Euryarchaeota, Firmicutes, Oomycetes, and Proteobacteria. The most dominant genera involve in biofilms formation belong to Agrobacterium , Anabaena , Azospirillum , Azotobacter , Bacillus , Bradyrhizobium , Burkholderia , Gluconacetobacter , Paenibacillus , Pseudomonas , Rhizobium , Trichoderma , Xanthomonas , and Xylella

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