1,720,985 research outputs found
GAMMA-PGA: Production and characterization of a versatile biopolymer by B. subtilis laboratory strains
No full textIn recent years the interest for potential applications of natural biopolymers has tremendously increased due to the growing demand of industrial processes based on safe raw materials. Poly γ-glutamic acid (γ-PGA) is a versatile unusual, water-soluble, anionic homopolyamide that is raising considerable industrial interests for the multitude of its potential applications. It is efficiently purified by natural bacterial isolates, mainly belonging to the genus Bacillus. Its cost is currently estimated to be much higher than that of conventional materials in current use and, for the moment, it is very difficult to prepare such high-molecular-weight polymer by chemical synthesis. For the industrial application of γ-PGA it is necessary to enhance its productivity and to find optimal fermentation conditions.
Recently, a new Bacillus subtilis producer strain has been derived from the fully genetically characterised laboratory strain 168 (1). The genetic, biochemical and physiological knowledge accumulated in such model organism allowed to devise genetic strategies for strain improvement and setting up of suitable growth conditions, overcoming the heuristic approach thus far applied with wild producers.
We have data showing the success of such strategic genetic engineering approaches: mutant strains with improved and sustained accumulation of the product have been obtained by introducing selected mutations.
The purification procedure has been carefully analysed and purity and size of the polymer have been checked by NMR and GPC. Copurification of enzymes and other by-products will be shown and discussed. The result is a competitive γ-PGA producer strain.
1) Osera, Amati, Calvio, Galizzi (2009). Microbiology, 155:2282-228
Vaccines to Overcome Antibiotic Resistance: The Challenge of Burkholderia cenocepacia
No full textCystic fibrosis (CF) patients are at particular risk of infection by microorganisms that are resistant to several antibiotics. About 3% of CF patients are colonized by Burkholderia cenocepacia, and this represents a major threat because of its intrinsic high level of drug resistance and the lack of a safe and effective treatment protocol. The development of anti-Burkholderia vaccines is a valuable and complementary approach, but only a few studies have been reported to date. In this review we discuss recent advances in the vaccine field and how new technologies, including structural reverse vaccinology, could drive the design of an effective vaccine against B. cenocepacia for use in preventive and therapeutic applications
Knockout of pgdS and ggt genes improves γ-PGA yield in B. subtilis.
No full textOne of the emerging biopolymers that are currently under active investigation is bacterial poly (γ-glutamic acid) (γ-PGA). However, before its full industrial exploitation, a substantial increase in microbial productivity is required. γ-PGA obtained from the Bacillus subtilis laboratory strain 168 offers the advantage of a producer characterized by a well defined genetic framework and simple manipulation techniques. In this strain, the knockout of genes for the major γ-PGA degrading enzymes, pgdS and ggt, leads to a considerable improvement in polymer yield, which attains levels analogous to the top wild γ-PGA producer strains. This study highlights the convenience of using the laboratory strain of B. subtilis over wild isolates in designing strain improvement strategies aimed at increasing γ-PGA productivity
The cell division protein FtsZ as a cellular target to hit cystic fibrosis pathogens
No full textCystic fibrosis is a rare genetic disease characterized by the production of dehydrated mucus in the lung able to trap bacteria and rendering their proliferation particularly dangerous, thus leading to chronic infections. Among these bacteria, Staphylococcus aureus and Pseudomonas aeruginosa play a major role while, within emerging pathogens, Stenotrophomonas maltophilia, Achromobacter xylosoxidans, Burkholderia cepacia complex species, as well as non-tuberculous mycobacteria are listed. Since a common feature of these bacteria is the high level of drug resistance, cell division, and in particular FtsZ, has been explored as a novel therapeutic target for the design of new molecules with antibacterial properties. This review summarizes and provides insight into recent advances in the discovery of compounds targeting FtsZ: the majority of them exhibit anti-staphylococcal activity, while a few were directed against the cystic fibrosis Gram negative pathogens
Gamma-PGA: Production, Characterization and Functionalization of a Versatile Biopolymer from Bacillus subtilis Laboratory Strains
No full textBurkholderia cenocepacia Infections in Cystic Fibrosis Patients: Drug Resistance and Therapeutic Approaches
Full text linkBurkholderia cenocepacia is an opportunistic pathogen particularly dangerous for cystic fibrosis (CF) patients. It can cause a severe decline in CF lung function possibly developing into a life-threatening systemic infection known as cepacia syndrome. Antibiotic resistance and presence of numerous virulence determinants in the genome make B. cenocepacia extremely difficult to treat. Better understanding of its resistance profiles and mechanisms is crucial to improve management of these infections. Here, we present the clinical distribution of B. cenocepacia described in the last 6 years and methods for identification and classification of epidemic strains. We also detail new antibiotics, clinical trials, and alternative approaches reported in the literature in the last 5 years to tackle B. cenocepacia resistance issue. All together these findings point out the urgent need of new and alternative therapies to improve CF patients’ life expectancy
New Antimicrobial Strategies to Treat Multi-Drug Resistant Infections Caused by Gram-Negatives in Cystic Fibrosis
No full text: People with cystic fibrosis (CF) suffer from recurrent bacterial infections which induce inflammation, lung tissue damage and failure of the respiratory system. Prolonged exposure to combinatorial antibiotic therapies triggers the appearance of multi-drug resistant (MDR) bacteria. The development of alternative antimicrobial strategies may provide a way to mitigate antimicrobial resistance. Here we discuss different alternative approaches to the use of classic antibiotics: anti-virulence and anti-biofilm compounds which exert a low selective pressure; phage therapies that represent an alternative strategy with a high therapeutic potential; new methods helping antibiotics activity such as adjuvants; and antimicrobial peptides and nanoparticle formulations. Their mechanisms and in vitro and in vivo efficacy are described, in order to figure out a complete landscape of new alternative approaches to fight MDR Gram-negative CF pathogens
The Evolution of Antimicrobial Resistance in <i>Acinetobacter baumannii</i> and New Strategies to Fight It
No full textAcinetobacter baumannii is considered one of the prioritized ESKAPE microorganisms for the research and development of novel treatments by the World Health Organization, especially because of its remarkable persistence and drug resistance. In this review, we describe how this can be acquired by the enzymatic degradation of antibiotics, target site modification, altered membrane permeability, multidrug efflux pumps, and their ability to form biofilms. Also, the evolution of drug resistance in A. baumannii, which is mainly driven by mobile genetic elements, is reported, with particular reference to plasmid-associated resistance, resistance islands, and insertion sequences. Finally, an overview of existing, new, and alternative therapies is provided
Poly(gamma-glutamic acid) (gamma-PGA): a versatile biopolymer for novel biotechnological applications. Production, characterization and functionalization of gamma-PGA from Bacillus subtilis laboratory strains
No full textMechanism of resistance to an antitubercular 2-thiopyridine derivative that is also active against Burkholderia cenocepacia.
Full text linkThe discovery of new compounds able to inhibit Burkholderia cenocepacia growth is of primary importance for cystic fibrosis patients. Here the mechanism of resistance to a new pyridine-derivative, already shown to be effective against Mycobacterium tuberculosis, and showing a good activity toward B. cenocepacia, was investigated. An increased expression of an RND efflux system was detected in resistant mutants, thus confirming their important role in B. cenocepacia antibiotic resistance
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