Are there bacterial bioprotectants besides Bacillus and Pseudomonas species?

2021 ◽  
pp. 375-400
Author(s):  
Emilio Montesinos ◽  
◽  
Anna Bonaterra ◽  
Keyword(s):  
Lactic Acid ◽  
Molecular Markers ◽  
Plant Pathogens ◽  
Genetic Manipulation ◽  
Strain Improvement ◽  
Mechanisms Of Action ◽  
Antagonistic Bacteria ◽  
Future Trends ◽  
Commercial Development ◽  
Pseudomonas Species

This chapter discusses the taxonomy of non-Bacillus and Pseudomonas (NBP) bioprotectant strains, including enterobacteria, actinomycetes, Sphingomonas, Methylobacterium, Agrobacterium-Rhizobium and Lactobacillus. The chapter reviews their mechanisms of action against plant pathogens. Sources of isolates and methods of isolation are discussed in building strain collections. The chapter then reviews procedures for screening antagonistic bacteria candidates as bioprotectants using biochemical and molecular markers, including the example of lactic acid bacteria. The chapter then covers strain improvement to increase fitness and efficacy in the field through physiological and genetic manipulation. Since they are essential for commercial development, biosafety issues are discussed, followed by an overview of patented substances and commercialized products. The chapter concludes with a summary and future trends in research on non-Bacillus and Pseudomonas species.

Fresh approaches to antibiotic production

1980 ◽  
Vol 290 (1040) ◽  
pp. 313-328 ◽  
Keyword(s):  
Polyethylene Glycol ◽  
Plant Pathogens ◽  
Growth Promotion ◽  
Antibiotic Production ◽  
Strain Improvement ◽  
Antibiotic Biosynthesis ◽  
Yield Improvement ◽  
Acquired Drug Resistance ◽  
Intensive Farming ◽  
New Antibiotics

New antibiotics are needed, ( a ) to control diseases that are refractory to existing ones either because of intrinsic or acquired drug resistance of the pathogen or because inhibition of the disease is difficult, at present, without damaging the host (fungal and viral diseases, and tumours), ( b ) for the control of plant pathogens and of invertebrates such as helminths, insects, etc., and ( c ) for growth promotion in intensive farming. Numerous new antibiotics are still being obtained from wild microbes, especially actinomycetes. Chemical modification of existing compounds has also had notable success. Here we explore the uses, actual and potential, of genetics to generate new antibiotics and to satisfy the ever-present need to increase yield. Yield improvement has depended in the past on mutation and selection, combined with optimization of fermentation conditions. Progress would be greatly accelerated by screening random recombinants between divergent high-yielding strains. Strain improvement may also be possible by the introduction of extra copies of genes of which the products are rate-limiting, or of genes conferring beneficial growth characteristics. Although new antibiotics can be generated by mutation, either through disturbing known biosyntheses or by activating ‘silent’ genes, we see more promise in interspecific recombination between strains producing different secondary metabolites, generating producers of ‘hybrid’ antibiotics. As with proposals for yield improvement, there are two major strategies for obtaining interesting recombinants of this kind: random recombination between appropriate strains, or the deliberate movement of particular biosynthetic abilities between strains. The development of protoplast technology in actinomycetes, fungi and bacilli has been instrumental in bringing these idealized strategies to the horizon. Protoplasts of the same or different species can be induced to fuse by polyethylene glycol. At least in intraspecific fusion of streptomycetes, random and high frequency recombination follows. Protoplasts can also be used as recipients for isolated DNA, again in the presence of polyethylene glycol, so that the deliberate introduction of particular genes into production strains can be realistically envisaged. Various kinds of DNA cloning vectors are being developed to this end. Gene cloning techniques also offer rich possibilities for the analysis of the genetic control of antibiotic biosynthesis, knowledge of which is, at present, minimal. The information that should soon accrue can be expected to have profound effects on the application of genetics to industrial microbiology.

scholarly journals Optimal markers for the identification ofColletotrichumspecies

2019 ◽  
Author(s):  
Willie Anderson dos Santos Vieira ◽  
Priscila Alves Bezerra ◽  
Anthony Carlos da Silva ◽  
Josiene Silva Veloso ◽  
Marcos Paz Saraiva Câmara ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Species Complex ◽  
Plant Pathogens ◽  
Phylogenetic Signal ◽  
Intergenic Spacer ◽  
Internal Transcribed Spacers ◽  
Type Locus ◽  
Phylogenetic Studies ◽  
Fungal Plant Pathogens ◽  
Species Complexes

ABSTRACTColletotrichumis among the most important genera of fungal plant pathogens. Molecular phylogenetic studies over the last decade have resulted in a much better understanding of the evolutionary relationships and species boundaries within the genus. There are now approximately 200 species accepted, most of which are distributed among 13 species complexes. Given their prominence on agricultural crops around the world, rapid identification of a large collection ofColletotrichumisolates is routinely needed by plant pathologists, regulatory officials, and fungal biologists. However, there is no agreement on the best molecular markers to discriminate species in each species complex. Here we calculate the barcode gap distance and intra/inter-specific distance overlap to evaluate each of the most commonly applied molecular markers for their utility as a barcode for species identification. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), histone-3 (HIS3), DNA lyase (APN2), intergenic spacer between DNA lyase and the mating-type locusMAT1-2-1 (APN2/MAT-IGS), and intergenic spacer between GAPDH and a hypothetical protein (GAP2-IGS) have the properties of good barcodes, whereas sequences of actin (ACT), chitin synthase (CHS-1) and nuclear rDNA internal transcribed spacers (nrITS) are not able to distinguish most species. Finally, we assessed the utility of these markers for phylogenetic studies using phylogenetic informativeness profiling, the genealogical sorting index (GSI), and Bayesian concordance analyses (BCA). Although GAPDH, HIS3 and β-tubulin (TUB2) were frequently among the best markers, there was not a single set of markers that were best for all species complexes. Eliminating markers with low phylogenetic signal tends to decrease uncertainty in the topology, regardless of species complex, and leads to a larger proportion of markers that support each lineage in the Bayesian concordance analyses. Finally, we reconstruct the phylogeny of each species complex using a minimal set of phylogenetic markers with the strongest phylogenetic signal and find the majority of species are strongly supported as monophyletic.

scholarly journals Antimicrobial activity of lactic acid bacteria isolated from garri on Escherichia coli strains isolated from clinical and environmental samples

2020 ◽  
Vol 12 (4) ◽  
pp. 357-365
Author(s):  
H.I. Atta ◽  
A. Gimba ◽  
T. Bamgbose
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Lactobacillus Plantarum ◽  
Lactobacillus Acidophilus ◽  
Plant Pathogens ◽  
Resistant Bacteria ◽  
Fermented Foods ◽  
Environmental Isolates ◽  
E Coli

Abstract. The production of bacteriocins by lactic acid bacteria affords them the ability to inhibit the growth of bacteria; they are particularly important in the biocontrol of human and plant pathogens. Lactic acid bacteria have been frequently isolated from fermented foods due to the high acidity these foods contain. In this study, lactic acid bacteria were isolated from garri, a popular Nigerian staple food, which is fermented from cassava, and their antagonistic activity against clinical and environmental isolates of Escherichia coli was determined. The species of Lactobacillus isolated include: Lactobacillus plantarum (50%), Lactobacillus fermentum (20%), Lactobacillus acidophilus (20%), and Lactobacillus salivarius (10%). Growth inhibition of the strains of E.coli was observed in Lactobacillus plantarum that inhibited the growth of both. The clinical and environmental isolates of E. coli were inhibited by Lactobacillus plantarum, while Lactobacillus acidophilus showed activity against only the clinical isolate. The greatest zone of inhibition against the strains of E. coli was recorded by Lactobacillus acidophilus (22.7±1.53 mm). The bacteriocins produced by Lactobacillus species have a good potential in the biocontrol of pathogens, and should be the focus of further studies on antibiotic resistant bacteria.

scholarly journals Droplet-based microfluidics as a future tool for strain improvement in lactic acid bacteria

2018 ◽  
Vol 366 (Supplement_1) ◽  
pp. i10-i16
Author(s):  
Jun Chen ◽  
Mike Vestergaard ◽  
Jing Shen ◽  
Christian Solem ◽  
Martin Dufva ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Strain Improvement ◽  
Cost Effective ◽  
Screening Tools ◽  
Strain Development ◽  
Mutant Selection ◽  
Mutagenesis Screen ◽  
Microbial Strain ◽  
Potential Use

ABSTRACT Strain development is frequently used to improve the performance and functionality of industrially important microbes. As traditional mutagenesis screen is especially utilized by the food industry to improve strains used in food fermentation, high-throughput and cost-effective screening tools are important in mutant selection. The emerging droplet-based microfluidics technology miniaturizes the volume for cell cultivation and phenotype interrogation down to the picoliter scales, which facilitates screening of microbes for improved phenotypical properties tremendously. In this mini review, we present recent application of the droplet-based microfluidics in microbial strain improvement with a focus on its potential use in the screening of lactic acid bacteria.

Physiological and molecular characterization of compost bacteria antagonistic to soil-borne plant pathogens

2017 ◽  
Vol 63 (5) ◽  
pp. 411-426 ◽  
Author(s):  
Rowida Mohamed ◽  
Emma Groulx ◽  
Stefanie Defilippi ◽  
Tamara Erak ◽  
James T. Tambong ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Antagonistic Activity ◽  
Antagonistic Bacteria ◽  
Antimicrobial Compounds ◽  
Fusarium Sambucinum ◽  
Inhibitory Compounds ◽  
Antimicrobial Lipopeptides ◽  
Chemical Pesticides ◽  
Insight Into

Disease suppressive composts have the potential to mitigate the risks associated with chemical pesticides. One of the main characteristics responsible for the suppressive nature of composts is their microbiological populations. To gain insight into the determinants responsible for their suppressive effects, we assayed composts to (i) isolate and identify beneficial antagonistic bacteria, (ii) quantify their antifungal and anti-oomycetal activities, (iii) extract inhibitory compounds produced by the bacteria, and (iv) identify antimicrobial lipopeptides produced by these bacteria. The antagonistic bacteria belonged to the genera Arthrobacter, Pseudomonas, Bacillus, Brevibacillus, Paenibacillus, and Rummeliibacillus and had the ability to antagonise the growth of Fusarium sambucinum, Verticillium dahliae, and (or) Pythium sulcatum. These bacteria produced antimicrobial compounds that affected the mycelial growth and (or) conidial germination of the pathogens. Mass spectrometry analyses showed the presence of various antimicrobial lipopeptides in Bacillus and Bacillus-related spp. extracts, demonstrating that they are responsible, at least in part, for the antagonistic activity of the bacteria. Results from this work provide greater insight into some of the biological, biochemical, and physiological determinants of suppressiveness in composts involved in the control of plant pathogens.

Exploration of the Use of the “Bialaphos Genes” for Improving Bioherbicide Efficacy

1996 ◽  
Vol 10 (3) ◽  
pp. 625-636 ◽  
Author(s):  
R. Charudattan ◽  
V. J. Prange ◽  
J. T. Devalerio
Keyword(s):  
Host Range ◽  
Xanthomonas Campestris ◽  
Plant Pathogens ◽  
Strain Improvement ◽  
Tetracycline Resistance ◽  
Plasmid Vector ◽  
E Coli ◽  
Normal Expression ◽  
Natural Hosts ◽  
Rot Disease

We are studying the possibility of altering the virulence and host range of a phytopathogen by transferring and expressing certain genes from the soil-dwelling saprophyte,Streptomyces hygroscopicus, in a plant pathogen model,Xanthomonas campestrispv.campestris(XCC). The genes, referred to herein as the “bialaphos genes,” encode the production of bialaphos, a potent glutamine-synthetase-inhibiting herbicide. This cluster of genes was originally isolated from several biosynthetically blocked mutants ofS. hygroscopicusand constructed into a plasmid vector, pBG9. We have transferred a fragment of the gene cluster into pLAFR3, a plasmid that functions in bothEscherichia coliand XCC and contains a tetracycline resistance marker. The resulting plasmid, named pIL-1, was used to transformE. coliand was incorporated into XCC by conjugation. The transfer of the fragment was confirmed by Southern analysis. The genes were maintained in XCC for about 47 generations in the absence of selection for tetracycline, and no changes in cultural phenotypes were seen in the transformed XCC (XCC/pIL-1). The XCC/pIL-1 cells were pathogenic to their natural hosts cabbage and broccoli, but induced an altered hypersensitive response in the nonhosts bean, pepper, sunflower, and tobacco. The pathogenic host-reaction, induced by the parent XCC, XCC/pLAFR3, and XCC/pIL-1, was a typical black rot disease in inoculated leaves of the two hosts. The nonhost reaction on the nonhost leaves was necrotic hypersensitivity, induced by XCC and XCC/pLAFR3, or the inhibition of hypersensitivity accompanied by only chlorosis at sites inoculated with XCC/pIL-1. We hypothesize that the altered hypersensitivity phenotype may be due to the transformed XCC becoming more compatible with the nonhosts, a step toward acquiring nonhost-virulence, or due to disruption of the normal expression of the hypersensitivity and pathogenicity genes in the transformed XCC. More work is needed to confirm that the introduced genes are being expressed in XCC. With further understanding, this approach may provide a useful model to study host range, virulence, and strain improvement of plant pathogens for biological control of weeds.

Genetic Manipulation of Broad Host-Range Fungi for Biological Control of Weeds

1990 ◽  
Vol 4 (3) ◽  
pp. 471-474 ◽  
Author(s):  
David C. Sands ◽  
Eugene J. Ford ◽  
R. Vincent Miller
Keyword(s):  
Host Range ◽  
Plant Pathogens ◽  
Genetic Manipulation ◽  
Broad Host Range ◽  
Biological Control Of Weeds ◽  
Term Survival ◽  
Induced Mutants ◽  
Highly Virulent ◽  
Exogenous Source

Few plant pathogens are both lethal and specific enough to be effective weed control agents. In short, highly specific organisms seldom kill. Two genetic approaches to overcome this problem are to delimit the host range of lethal pathogens or to enhance the efficacy of host-specific ones. Narrowing the virulence or survival of a deadly pathogen seems more plausible than imparting new characters to a nonlethal organism. Our approach has been to genetically restrict the host range or to decrease the survival and/or spread ofSclerotinia sclerotiorum(Lib.) de Bary, a highly virulent and aggressive pathogen of several weeds. Working with this fungus, three classes of induced mutants which meet criteria for delimitation were obtained: auxotrophic mutants that only attack plants when applied concomitantly with an exogenous source of the required nutrient; mutants unable to form sclerotia, structures required for long-term survival and precursors to fruiting bodies; and mutants with reduced virulence and/or host ranges. These studies demonstrate the validity of genetically improving bioherbicides and greatly expanding the number of fungi that may be useful as bioherbicides.

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