EXPLORATION OF BACTERIA Symbionts Mangrove Waste FOR THE PRODUCTION OF DECOMPOSTER

Mangrove waste comprises of naturally decomposed dead mangrove leaves, twigs, and branches. This research aims to determine the types of bacterial symbionts in mangrove waste with potency as anti-bacterial agents. These anti-bacterial agents will subsequently be used in the production of compost with bio-activators. The research process involves isolation of symbiont bacteria, identification for symbiont bacteria with potency as anti-bacterial agent, DNA extraction using High Pure PCR Temperature Preparation Kit (Roche), DNA amplification by PCR 16s rDNA, and DNA Sequencing. Resulting amplified 16S rDNA are analyzed and then sequenced using Genetix program. Symbionts with identified anti-bacterial properties are used in bio-activator production. Samples of Sargassum seaweed are treated separately with resulting bio-activator product from the research and other bio-activator products for nutritional content comparison. Four types of symbiont bacteria are identified as potential anti-bacterial agents, namely Pseudomonas sp., Flavobacterium sp., Acinetobacter sp., Bacillus subtilis. It is further found that bio-activator products from mangrove waste have better quality compared to those found in the market and non-bio activator added liquid organic fertilizers. Therefore, bio-activators from mangrove waste is a potential alternative as natural bio-activator product

Antisense PNA accumulates in Escherichia coli and mediates a long post-antibiotic effect

Antisense agents that target growth-essential genes display surprisingly potent bactericidal properties. In particular, peptide nucleic acid (PNA) and phosphorodiamidate morpholino oligomers linked to cationic carrier peptides are effective in time kill assays and as inhibitors of bacterial peritonitis in mice. It is unclear how these relatively large antimicrobials overcome stringent bacterial barriers and mediate killing. Here we determined the transit kinetics of peptide-PNAs and observed an accumulation of cell-associated PNA in Escherichia coli and slow efflux. An inhibitor of drug efflux pumps did not alter peptide-PNA potency, indicating a lack of active efflux from cells. Consistent with cell retention, the post-antibiotic effect (PAE) of the anti-acyl carrier protein (acpP) peptide-PNA was greater than 11 hours. Bacterial cell accumulation and a long PAE are properties of significant interest for antimicrobial development.Peer reviewe

In situ synthesis of size-controlled, stable silver nanoparticles within ultrashort peptide hydrogels and their anti-bacterial properties

We have developed a silver-releasing biomaterial with promising potential for wound healing applications. The material is made of ultrashort peptides which can self-assemble in water to form hydrogels. Silver nanoparticles (Ag NPs) were synthesized in situ within the biomaterial, using only UV irradiation and no additional chemical reducing agents. The synthetic strategy allows precise control of the nanoparticle size, with the network of peptide fibers preventing aggregation of Ag NPs. The biomaterial shows increased mechanical strength compared to the hydrogel control. We observed a sustained release of Ag NPs over a period of 14 days. This is a crucial prerequisite for effective anti-bacterial therapy. The ability to inhibit bacterial growth was tested using different bacterial strains, namely gram-negative Escherichia coli and Pseudomonas aeruginosa and gram-positive Staphylococcus aureus. Inhibition of bacterial growth was observed for all strains. The best results were obtained for Pseudomonas aeruginosa which is known for exhibiting multidrug resistance. Biocompatibility studies on HDFa cells, using Ag NP-containing hydrogels, did not show any significant influence on cell viability. We propose this silver-releasing hydrogel as an excellent biomaterial with great potential for applications in wound healing due to its low silver content, sustained silver nanoparticle release and biocompatibility

Strategies to prevent the occurrence of resistance against antibiotics by using advanced materials

This is a post-peer-review, pre-copyedit version of an article published in Applied microbiology and biotechnology The final authenticated version is available online at: http://dx.doi.org/10.1007/s00253-018-8776-0Drug resistance occurrence is a global healthcare concern responsible for the increased morbidity and mortality in hospitals, time of hospitalisation and huge financial loss. The failure of the most antibiotics to kill Bsuperbugs^ poses the urgent need to develop innovative strategies aimed at not only controlling bacterial infection but also the spread of resistance. The prevention of pathogen host invasion by inhibiting bacterial virulence and biofilm formation, and the utilisation of bactericidal agents with different mode of action than classic antibiotics are the two most promising new alternative strategies to overcome antibiotic resistance. Based on these novel approaches, researchers are developing different advanced materials (nanoparticles, hydrogels and surface coatings) with novel antimicrobial properties. In this review, we summarise the recent advances in terms of engineered materials to prevent bacteria-resistant infections according to the antimicrobial strategies underlying their design.Peer ReviewedPostprint (author's final draft

Can we prevent antimicrobial resistance by using antimicrobials better?

Since their development over 60 years ago, antimicrobials have become an integral part of healthcare practice worldwide. Recently, this has been put in jeopardy by the emergence of widespread antimicrobial resistance, which is one of the major problems facing modern medicine. In the past, the development of new antimicrobials kept us one step ahead of the problem of resistance, but only three new classes of antimicrobials have reached the market in the last thirty years. A time is therefore approaching when we may not have effective treatment against bacterial infections, particularly for those that are caused by Gram-negative organisms. An important strategy to reduce the development of antimicrobial resistance is to use antimicrobials more appropriately, in ways that will prevent resistance. This involves a consideration of the pharmacokinetic and pharmacodynamics properties of antimicrobials, the possible use of combinations, and more appropriate choice of antimicrobials, which may include rapid diagnostic testing and antimicrobial cycling. Examples given in this review include Mycobacterium tuberculosis, Gram-negative and Gram-positive organisms. We shall summarise the current evidence for these strategies and outline areas for future development

Pyoverdine and proteases affect the response of pseudomonas aeruginosa to gallium in human serum

Gallium is an iron mimetic which has recently been repurposed as an antibacterial agent due to its capability to disrupt bacterial iron metabolism. In this study, the antibacterial activity of gallium nitrate [Ga(NO3)3] was investigated in complement-free human serum (HS) on 55 Pseudomonas aeruginosa clinical isolates from cystic fibrosis and non-cystic fibrosis patients. The susceptibility of P. aeruginosa to Ga(NO3)3 in HS was dependent on the bacterial ability to acquire iron from serum binding proteins (i.e., transferrin). The extent of serum protein degradation correlated well with P. aeruginosa growth in HS, while pyoverdine production did not. However, pyoverdine-deficient P. aeruginosa strains were unable to grow in HS and overcome iron restriction, albeit capable of releasing proteases. Predigestion of HS with proteinase K promoted the growth of all strains, irrespective of their ability to produce proteases and/or pyoverdine. The MICs of Ga(NO3)3 were higher in HS than in an iron-poor Casamino Acids medium, where proteolysis does not affect iron availability. Coherently, strains displaying high proteolytic activity were less susceptible to Ga(NO3)3 in HS. Our data support a model in which both pyoverdine and proteases affect the response of P. aeruginosa to Ga(NO3)3 in HS. The relatively high Ga(NO3)3 concentration required to inhibit the growth of highly proteolytic P. aeruginosa isolates in HS poses a limitation to the potential of Ga(NO3)3 in the treatment of P. aeruginosa bloodstream infections

A review of selected bee products as potential anti-bacterial, anti-fungal, and anti-viral agents

Antimicrobial resistance (AMR) is one of the greatest medical challenges the world faces. It was estimated recently that by 2050, AMR will account for 10 million extra deaths annually with additional economic costs in the region of $100 trillion. In order to combat this, novel antimicrobial agents with a broad spectrum of activity are required. Bee products, including; honey, propolis, defensins, royal jelly, bee pollen and venom have been used to treat infectious diseases for several centuries, although they were largely disregarded by Western medicine during the antibiotic era. There has since been a resurgence in interest in their antimicrobial properties, especially due to their reported activity against multi-drug resistant pathogens displaying high levels of AMR. In this paper we review the current scientific literature of honey, propolis, honey bee, defensins, royal jelly, bee pollen and bee venom. We highlight the antimicrobial activity each of these products has displayed and potential future research directions

Subinhibitory concentrations of trimethoprim and sulfamethoxazole prevent biofilm formation by Acinetobacter baumannii through inhibition of Csu pilus expression

ABSTRACT Acinetobacter baumannii is emerging as a multidrug-resistant nosocomial pathogen of increasing threat to human health worldwide. Pili are important bacterial virulence factors, playing a role in attachment to host cells and biofilm formation. The Csu pilus, which is assembled via the chaperone-usher secretion system, has been studied in A. baumannii ATCC 19606. Here we show that, in opposition to previous reports, the common laboratory strain ATCC 17978 produces Csu pili. We found that, although ATCC 17978 was resistant to sulfamethoxazole (Smx) and trimethoprim (Tmp), subinhibitory concentrations of these antibiotics abolished the expression of Csu and consequently produced a dramatic reduction in biofilm formation by ATCC 17978. Smx and Tmp acted synergistically to inhibit the enzymatic systems involved in the bacterial synthesis of tetrahydrofolate (THF), which is required for the synthesis of nucleotides. The effects of these antibiotics were partially relieved by exogenous THF addition, indicating that Smx and Tmp turn off Csu assembly by inducing folate stress. We propose that, for Acinetobacter , nanomolar concentrations of Smx and Tmp represent a “danger signal.” In response to this signal, Csu expression is repressed, allowing biofilm dispersal and escape from potentially inhibitory concentrations of antibiotics. The roles of antibiotics as signaling molecules are being increasingly acknowledged, with clear implications for both the treatment of bacterial diseases and the understanding of complex microbial interactions in the environment. </jats:p

Antioxidant Capacity and Antimicrobial Activity of Commercial Samples of Guava Leaves (\u3cem\u3ePsidium guajava\u3c/em\u3e)

Psidium guajava is a small tree native to South and Central America. Guava leaves have traditionally been used for treating different illnesses. These benefits can be attributed to phenolics and flavonoids produced by guava. The chemical composition of guava leaf extracts was correlated with biological activity. Total phenolics, total flavonoids, ABTS/DPPH, TZM-bl, plaque reduction, XTT, spectrophotometric and Kirby-Bauer assays were used to test phenols, flavonoids, antioxidant properties, antiviral activity, cytotoxicity, and antibacterial activity, respectively. The median cytotoxicity concentration and half-maximal effective concentration values were obtained in order to determine antiviral selectivity against human immunodeficiency virus type 1 and herpes simplex virus type 1. Antibacterial activity against Escherichia coli and Bacillus subtilis were evaluated using a spectrophotometric assay and Kirby-Bauer test. The guava leaf extracts had a high phenol (0.8 to 2.1 GAE mg/mL) and flavonoid (62.7 to 182.1 Rutin Eq mg/g DW) content that correlated with high antioxidant capacity and selective antiviral activity (therapeutic index values above 10). Results of antibacterial tests indicated that the extracts have activity against gram-negative and gram-positive bacteria