Efficient Plant Biomass Degradation by Thermophilic Fungus Myceliophthora heterothallica

ABSTRACTRapid and efficient enzymatic degradation of plant biomass into fermentable sugars is a major challenge for the sustainable production of biochemicals and biofuels. Enzymes that are more thermostable (up to 70°C) use shorter reaction times for the complete saccharification of plant polysaccharides compared to hydrolytic enzymes of mesophilic fungi such asTrichodermaandAspergillusspecies. The genusMyceliophthoracontains four thermophilic fungi producing industrially relevant thermostable enzymes. Within this genus, isolates belonging toM. heterothallicawere recently separated from the well-described speciesM. thermophila. We evaluate here the potential ofM. heterothallicaisolates to produce efficient enzyme mixtures for biomass degradation. Compared to the other thermophilicMyceliophthoraspecies, isolates belonging toM. heterothallicaandM. thermophilagrew faster on pretreated spruce, wheat straw, and giant reed. According to their protein profiles andin vitroassays after growth on wheat straw, (hemi-)cellulolytic activities differed strongly betweenM. thermophilaandM. heterothallicaisolates. Compared toM. thermophila,M. heterothallicaisolates were better in releasing sugars from mildly pretreated wheat straw (with 5% HCl) with a high content of xylan. The high levels of residual xylobiose revealed that enzyme mixtures ofMyceliophthoraspecies lack sufficient β-xylosidase activity. Sexual crossing of twoM. heterothallicashowed that progenies had a large genetic and physiological diversity. In the future, this will allow further improvement of the plant biomass-degrading enzyme mixtures ofM. heterothallica.

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Optimization of β-1,4-Endoxylanase Production by an Aspergillus niger Strain Growing on Wheat Straw and Application in Xylooligosaccharides Production

Molecules ◽

10.3390/molecules26092527 ◽

2021 ◽

Vol 26 (9) ◽

pp. 2527

Author(s):

Zahra Azzouz ◽

Azzeddine Bettache ◽

Nawel Boucherba ◽

Alicia Prieto ◽

Maria Jesus Martinez ◽

...

Keyword(s):

Aspergillus Niger ◽

Wheat Straw ◽

Plant Biomass ◽

Residual Activity ◽

Exchange Chromatography ◽

Glycosyl Hydrolases ◽

Biomass Degradation ◽

Xylan Hydrolysis ◽

Rsm Optimization ◽

Single Carbon Source

Plant biomass constitutes the main source of renewable carbon on the planet. Its valorization has traditionally been focused on the use of cellulose, although hemicellulose is the second most abundant group of polysaccharides on Earth. The main enzymes involved in plant biomass degradation are glycosyl hydrolases, and filamentous fungi are good producers of these enzymes. In this study, a new strain of Aspergillus niger was used for hemicellulase production under solid-state fermentation using wheat straw as single-carbon source. Physicochemical parameters for the production of an endoxylanase were optimized by using a One-Factor-at-a-Time (OFAT) approach and response surface methodology (RSM). Maximum xylanase yield after RSM optimization was increased 3-fold, and 1.41- fold purification was achieved after ultrafiltration and ion-exchange chromatography, with about 6.2% yield. The highest activity of the purified xylanase was observed at 50 °C and pH 6. The enzyme displayed high thermal and pH stability, with more than 90% residual activity between pH 3.0–9.0 and between 30–40 °C, after 24 h of incubation, with half-lives of 30 min at 50 and 60 °C. The enzyme was mostly active against wheat arabinoxylan, and its kinetic parameters were analyzed (Km = 26.06 mg·mL−1 and Vmax = 5.647 U·mg−1). Wheat straw xylan hydrolysis with the purified β-1,4 endoxylanase showed that it was able to release xylooligosaccharides, making it suitable for different applications in food technology.

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ABC Transporters Required for Hexose Uptake byClostridium phytofermentans

Journal of Bacteriology ◽

10.1128/jb.00241-19 ◽

2019 ◽

Vol 201 (15) ◽

Cited By ~ 2

Author(s):

Tristan Cerisy ◽

Alba Iglesias ◽

William Rostain ◽

Magali Boutard ◽

Christine Pelle ◽

...

Keyword(s):

Abc Transporters ◽

Extracellular Enzymes ◽

Plant Biomass ◽

Carbon Sources ◽

Anaerobic Bacteria ◽

Model Organism ◽

Industrial Transformation ◽

Content Type ◽

Plant Matter

ABSTRACTThe mechanisms by which bacteria uptake solutes across the cell membrane broadly impact their cellular energetics. Here, we use functional genomic, genetic, and biophysical approaches to reveal howClostridium(Lachnoclostridium)phytofermentans, a model bacterium that ferments lignocellulosic biomass, uptakes plant hexoses using highly specific, nonredundant ATP-binding cassette (ABC) transporters. We analyze the transcription patterns of its 173 annotated sugar transporter genes to find those upregulated on specific carbon sources. Inactivation of these genes reveals that individual ABC transporters are required for uptake of hexoses and hexo-oligosaccharides and that distinct ABC transporters are used for oligosaccharides versus their constituent monomers. The thermodynamics of sugar binding shows that substrate specificity of these transporters is encoded by the extracellular solute-binding subunit. As sugars are not phosphorylated during ABC transport, we identify intracellular hexokinases based onin vitroactivities. These mechanisms used byClostridiato uptake plant hexoses are key to understanding soil and intestinal microbiomes and to engineer strains for industrial transformation of lignocellulose.IMPORTANCEPlant-fermentingClostridiaare anaerobic bacteria that recycle plant matter in soil and promote human health by fermenting dietary fiber in the intestine.Clostridiadegrade plant biomass using extracellular enzymes and then uptake the liberated sugars for fermentation. The main sugars in plant biomass are hexoses, and here, we identify how hexoses are taken in to the cell by the model organismClostridium phytofermentans. We show that this bacterium uptakes hexoses using a set of highly specific, nonredundant ABC transporters. Once in the cell, the hexoses are phosphorylated by intracellular hexokinases. This study provides insight into the functioning of abundant members of soil and intestinal microbiomes and identifies gene targets to engineer strains for industrial lignocellulosic fermentation.

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A Novel Cys2His2 Zinc Finger Homolog of AZF1 Modulates Holocellulase Expression in Trichoderma reesei

mSystems ◽

10.1128/msystems.00161-19 ◽

2019 ◽

Vol 4 (4) ◽

Cited By ~ 4

Author(s):

Amanda Cristina Campos Antonieto ◽

Karoline Maria Vieira Nogueira ◽

Renato Graciano de Paula ◽

Luísa Czamanski Nora ◽

Murilo Henrique Anzolini Cassiano ◽

...

Keyword(s):

Trichoderma Reesei ◽

Filamentous Fungi ◽

Plant Cell Wall ◽

Plant Biomass ◽

Regulatory Elements ◽

Biomass Degradation ◽

Control Of Gene Expression ◽

Content Type ◽

Encoding Genes

ABSTRACT Filamentous fungi are remarkable producers of enzymes dedicated to the degradation of sugar polymers found in the plant cell wall. Here, we integrated transcriptomic data to identify novel transcription factors (TFs) related to the control of gene expression of lignocellulosic hydrolases in Trichoderma reesei and Aspergillus nidulans. Using various sets of differentially expressed genes, we identified some putative cis-regulatory elements that were related to known binding sites for Saccharomyces cerevisiae TFs. Comparative genomics allowed the identification of six transcriptional factors in filamentous fungi that have corresponding S. cerevisiae homologs. Additionally, a knockout strain of T. reesei lacking one of these TFs (S. cerevisiae AZF1 homolog) displayed strong reductions in the levels of expression of several cellulase-encoding genes in response to both Avicel and sugarcane bagasse, revealing a new player in the complex regulatory network operating in filamentous fungi during plant biomass degradation. Finally, RNA sequencing (RNA-seq) analysis showed the scope of the AZF1 homologue in regulating a number of processes in T. reesei, and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) provided evidence for the direct interaction of this TF in the promoter regions of cel7a, cel45a, and swo. Therefore, we identified here a novel TF which plays a positive effect in the expression of cellulase-encoding genes in T. reesei. IMPORTANCE In this work, we used a systems biology approach to map new regulatory interactions in Trichoderma reesei controlling the expression of genes encoding cellulase and hemicellulase. By integrating transcriptomics related to complex biomass degradation, we were able to identify a novel transcriptional regulator which is able to activate the expression of these genes in response to two different cellulose sources. In vivo experimental validation confirmed the role of this new regulator in several other processes related to carbon source utilization and nutrient transport. Therefore, this work revealed novel forms of regulatory interaction in this model system for plant biomass deconstruction and also represented a new approach that could be easy applied to other organisms.

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In vitro digestibility and pasting properties of epichlorohydrin modified cassava starch

Nutrition & Food Science ◽

10.1108/nfs-11-2015-0151 ◽

2016 ◽

Vol 46 (4) ◽

pp. 517-528 ◽

Cited By ~ 1

Author(s):

Marta Aurelia Horianski ◽

Juan Manuel Peralta ◽

Luis Alberto Brumovsky

Keyword(s):

Reaction Time ◽

Resistant Starch ◽

Reaction Times ◽

Cassava Starch ◽

Pasting Properties ◽

Cross Linking ◽

In Vitro Digestibility ◽

Total Dietary Fiber ◽

Content Type

Purpose The purpose of this study was to analyze the influence of epichlorohydrin (ECH) concentration and reaction time on the food-grade resistant starch production and its pasting properties by using native cassava starch of Misiones-Argentina origin. Design/methodology/approach Cassava starch was modified using ECH (0.30 and 0.15 per cent) during 4 or 8 h. Digestibility was evaluated by determining resistant starch as total dietary fiber. Pasting properties and the cross-linking degree were studied using a micro-viscoamylograph (Brabender). Findings Resistant starch content was not influenced by ECH concentration and reaction time. Cross-linking was detected at higher reaction times (8 h) and ECH concentrations (0.30 per cent), where a decrease in viscosity peaks by more than 80 per cent was observed. Both pasting temperature and breakdown were increased, whereas a decrease in retrogradation was detected. Practical implications Starches can be suitable for different food applications. This is because of the ability to modify its pasting properties and the invariability of the in vitro digestibility of cassava starch as a result of using ECH (at concentrations approved by local and regional legislation) and reaction times of 4 and 8 h. Originality/value Information related to the modification of cassava starch using ECH is scarce or not available nowadays in literature.

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Establishment of a Simple Lactobacillus plantarum Cell Consortium for Cellulase-Xylanase Synergistic Interactions

Applied and Environmental Microbiology ◽

10.1128/aem.01211-13 ◽

2013 ◽

Vol 79 (17) ◽

pp. 5242-5249 ◽

Cited By ~ 31

Author(s):

Sarah Moraïs ◽

Naama Shterzer ◽

Inna Rozman Grinberg ◽

Geir Mathiesen ◽

Vincent G. H. Eijsink ◽

...

Keyword(s):

Wheat Straw ◽

Lactobacillus Plantarum ◽

Plant Biomass ◽

Soluble Sugar ◽

Acid Tolerance ◽

Cellulolytic Bacterium ◽

Synergistic Activity ◽

Heterologous Proteins ◽

Content Type ◽

Highly Active

ABSTRACTLactobacillus plantarumis an attractive candidate for bioprocessing of lignocellulosic biomass due to its high metabolic variability, including its ability to ferment both pentoses and hexoses, as well as its high acid tolerance, a quality often utilized in industrial processes. This bacterium grows naturally on biomass; however, it lacks the inherent ability to deconstruct lignocellulosic substrates. As a first step toward engineering lignocellulose-converting lactobacilli, we have introduced genes coding for a GH6 cellulase and a GH11 xylanase from a highly active cellulolytic bacterium intoL. plantarum. For this purpose, we employed the recently developed pSIP vectors for efficient secretion of heterologous proteins. Both enzymes were secreted byL. plantarumat levels estimated at 0.33 nM and 3.3 nM, for the cellulase and xylanase, respectively, in culture at an optical density at 600 nm (OD600) of 1. Transformed cells demonstrated the ability to degrade individually either cellulose or xylan and wheat straw. When mixed together to form a two-strain cell-based consortium secreting both cellulase and xylanase, they exhibited synergistic activity in the overall release of soluble sugar from wheat straw. This result paves the way toward metabolic harnessing ofL. plantarumfor novel biorefining applications, such as production of ethanol and polylactic acid directly from plant biomass.

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Priming of Plant Growth Promotion by Volatiles of Root-AssociatedMicrobacteriumspp.

Applied and Environmental Microbiology ◽

10.1128/aem.01865-18 ◽

2018 ◽

Vol 84 (22) ◽

Cited By ~ 17

Author(s):

Viviane Cordovez ◽

Sharella Schop ◽

Kees Hordijk ◽

Hervé Dupré de Boulois ◽

Filip Coppens ◽

...

Keyword(s):

Plant Growth ◽

Volatile Compounds ◽

Plant Growth Promotion ◽

Large Scale ◽

Plant Biomass ◽

Growth Promotion ◽

Shoot Biomass ◽

Content Type ◽

Prolonged Contact

ABSTRACTVolatile compounds produced by plant-associated microorganisms represent a diverse resource to promote plant growth and health. Here, we investigated the effect of volatiles from root-associatedMicrobacteriumspecies on plant growth and development. Volatiles of eight strains induced significant increases in shoot and root biomass ofArabidopsisbut differed in their effects on root architecture.Microbacteriumstrain EC8 also enhanced root and shoot biomass of lettuce and tomato. Biomass increases were also observed for plants exposed only briefly to volatiles from EC8 prior to transplantation of the seedlings to soil. These results indicate that volatiles from EC8 can prime plants for growth promotion without direct and prolonged contact. We further showed that the induction of plant growth promotion is tissue specific; that is, exposure of roots to volatiles from EC8 led to an increase in plant biomass, whereas shoot exposure resulted in no or less growth promotion. Gas chromatography–quadrupole time of flight mass spectometry (GC–QTOF-MS) analysis revealed that EC8 produces a wide array of sulfur-containing compounds, as well as ketones. Bioassays with synthetic sulfur volatile compounds revealed that the plant growth response to dimethyl trisulfide was concentration-dependent, with a significant increase in shoot weight at 1 μM and negative effects on plant biomass at concentrations higher than 1 mM. Genome-wide transcriptome analysis of volatile-exposedArabidopsisseedlings showed upregulation of genes involved in assimilation and transport of sulfate and nitrate. Collectively, these results show that root-associatedMicrobacteriumprimes plants, via the roots, for growth promotion, most likely via modulation of sulfur and nitrogen metabolism.IMPORTANCEIn the past decade, various studies have described the effects of microbial volatiles on other (micro)organismsin vitro, but their broad-spectrum activityin vivoand the mechanisms underlying volatile-mediated plant growth promotion have not been addressed in detail. Here, we revealed that volatiles from root-associated bacteria of the genusMicrobacteriumcan enhance the growth of different plant species and can prime plants for growth promotion without direct and prolonged contact between the bacterium and the plant. Collectively, these results provide new opportunities for sustainable agriculture and horticulture by exposing roots of plants only briefly to a specific blend of microbial volatile compounds prior to transplantation of the seedlings to the greenhouse or field. This strategy has no need for large-scale introduction or root colonization and survival of the microbial inoculant.

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Proteomic Analysis of the Burkholderia pseudomallei Type II Secretome Reveals Hydrolytic Enzymes, Novel Proteins, and the Deubiquitinase TssM

Infection and Immunity ◽

10.1128/iai.01739-14 ◽

2014 ◽

Vol 82 (8) ◽

pp. 3214-3226 ◽

Cited By ~ 32

Author(s):

Mary N. Burtnick ◽

Paul J. Brett ◽

David DeShazer

Keyword(s):

Burkholderia Pseudomallei ◽

Signal Sequence ◽

Hydrolytic Enzymes ◽

Opportunistic Pathogen ◽

Etiologic Agent ◽

Type Ii ◽

Secretion Systems ◽

Content Type

ABSTRACTBurkholderia pseudomallei, the etiologic agent of melioidosis, is an opportunistic pathogen that harbors a wide array of secretion systems, including a type II secretion system (T2SS), three type III secretion systems (T3SS), and six type VI secretion systems (T6SS). The proteins exported by these systems provideB. pseudomalleiwith a growth advantagein vitroandin vivo, but relatively little is known about the full repertoire of exoproducts associated with each system. In this study, we constructed deletion mutations ingspDandgspE, T2SS genes encoding an outer membrane secretin and a cytoplasmic ATPase, respectively. The secretion profiles ofB. pseudomalleiMSHR668 and its T2SS mutants were noticeably different when analyzed by SDS-PAGE. We utilized liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify proteins present in the supernatants ofB. pseudomalleiMSHR668 andB. pseudomalleiΔgspDgrown in rich and minimal media. The MSHR668 supernatants contained 48 proteins that were either absent or substantially reduced in the supernatants of ΔgspDstrains. Many of these proteins were putative hydrolytic enzymes, including 12 proteases, two phospholipases, and a chitinase. Biochemical assays validated the LC-MS/MS results and demonstrated that the export of protease, phospholipase C, and chitinase activities is T2SS dependent. Previous studies had failed to identify the mechanism of secretion of TssM, a deubiquitinase that plays an integral role in regulating the innate immune response. Here we present evidence that TssM harbors an atypical signal sequence and that its secretion is mediated by the T2SS. This study provides the first in-depth characterization of theB. pseudomalleiT2SS secretome.

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Two Distinct α-l-Arabinofuranosidases in Caldicellulosiruptor Species Drive Degradation of Arabinose-Based Polysaccharides

Applied and Environmental Microbiology ◽

10.1128/aem.00574-17 ◽

2017 ◽

Vol 83 (13) ◽

Cited By ~ 9

Author(s):

Mohammad Abu Saleh ◽

Wen-Jie Han ◽

Ming Lu ◽

Bing Wang ◽

Huayue Li ◽

...

Keyword(s):

Chemical Structure ◽

Plant Biomass ◽

Glycoside Hydrolases ◽

Biomass Degradation ◽

Content Type ◽

Complex Chemical ◽

Key Factor ◽

Fuels And Chemicals ◽

Hydrolysis Of ◽

Hydrolysis Activity

ABSTRACT Species in the extremely thermophilic genus Caldicellulosiruptor can degrade unpretreated plant biomass through the action of multimodular glycoside hydrolases. To date, most focus with these bacteria has been on hydrolysis of glucans and xylans, while the biodegradation mechanism for arabinose-based polysaccharides remains unclear. Here, putative α-l-arabinofuranosidases (AbFs) were identified in Caldicellulosiruptor species by homology to less-thermophilic versions of these enzymes. From this screen, an extracellular XynF was determined to be a key factor in hydrolyzing α-1,2-, α-1,3-, and α-1,5-l-arabinofuranosyl residues of arabinose-based polysaccharides. Combined with a GH11 xylanase (XynA), XynF increased arabinoxylan hydrolysis more than 6-fold compared to the level seen with XynA alone, likely the result of XynF removing arabinofuranosyl side chains to generate linear xylans that were readily degraded. A second AbF, the intracellular AbF51, preferentially cleaved the α-1,5-l-arabinofuranosyl glycoside bonds within sugar beet arabinan. β-Xylosidases, such as GH39 Xyl39B, facilitated the hydrolysis of arabinofuranosyl residues at the nonreducing terminus of the arabinose-branched xylo-oligosaccharides by AbF51. These results demonstrate the separate but complementary contributions of extracellular XynF and cytosolic AbF51 in processing the bioconversion of arabinose-containing oligosaccharides to fermentable monosaccharides. IMPORTANCE Degradation of hemicellulose, due to its complex chemical structure, presents a major challenge during bioconversion of lignocellulosic biomass to biobased fuels and chemicals. Degradation of arabinose-containing polysaccharides, in particular, can be a key bottleneck in this process. Among Caldicellulosiruptor species, the multimodular arabinofuranosidase XynF is present in only selected members of this genus. This enzyme exhibited high hydrolysis activity, broad specificity, and strong synergism with other hemicellulases acting on arabino-polysaccharides. An intracellular arabinofuranosidase, AbF51, occurs in all Caldicellulosiruptor species and, in conjunction with xylosidases, processes the bioconversion of arabinose-branched oligosaccharides to fermentable monosaccharides. Taken together, the data suggest that plant biomass degradation in Caldicellulosiruptor species involves extracellular XynF that acts synergistically with other hemicellulases to digest arabino-polysaccharides that are subsequently transported and degraded further by intracellular AbF51 to produce short-chain arabino sugars.

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Preferential Packing of Acidic Glycosidases and Proteases into Bacteroides Outer Membrane Vesicles

mBio ◽

10.1128/mbio.00909-14 ◽

2014 ◽

Vol 5 (2) ◽

Cited By ~ 89

Author(s):

Wael Elhenawy ◽

Mykhaylo O. Debelyy ◽

Mario F. Feldman

Keyword(s):

Gut Microbiota ◽

Outer Membrane ◽

Hydrolytic Enzymes ◽

Membrane Vesicles ◽

Short Chain Fatty Acids ◽

Outer Membrane Vesicles ◽

Content Type ◽

High Prevalence ◽

Secretion Pathways

ABSTRACTOuter membrane vesicles (OMV) are spherical membranous structures released from the outer membrane (OM) of Gram-negative bacteria. OMV have been proposed to play several different roles during both pathogenesis and symbiosis. Despite the fact that OMV were described several decades ago, their biogenesis is a poorly characterized process. Whether OMV are produced by an active mechanism or by passive disintegration of the OM is a still matter of controversy.Bacteroides fragilisandBacteroides thetaiotaomicronare important members of the human microbiota. In this work, we determined and compared the protein compositions of OM and OMV fromB. fragilisandB. thetaiotaomicron. SDS-PAGE analysis of both fractions revealed dramatically different protein profiles. Proteomic analysis of OM and OMV inB. fragilisidentified more than 40 proteins found exclusively in OMV and more than 30 proteins detectable only in the OM. The OMV-specific proteome showed a high prevalence of glycosidases and proteases, some of which were shown to be activein vitro. Similar results were obtained forB. thetaiotaomicron. Most of the OMV-exclusive proteins were acidic. Based on these results, we propose that these species possess machinery devoted to selectively pack acidic proteins into the OMV. These OMV equipped with hydrolytic enzymes could help in securing nutrients for the benefit of the whole bacterial community present in the microbiota, uncovering a novel function for bacterial OMV.IMPORTANCEThe members of genusBacteroidesare key players in the symbiosis between the human host and the gut microbiota. It is known for its ability to degrade a wide variety of glycans that are not substrates for human glycosidases. The cleaved glycans can be utilized byBacteroidesand other microbiota members, resulting in the production of short-chain fatty acids that are beneficial for the host. Although members of the genusBacteroidesare known to secrete different hydrolases, their secretion pathways remain uncharacterized. In this article, we show thatB. fragilisandB. thetaiotaomicronpreferentially pack a large number of hydrolases in outer membrane vesicles (OMV). Most of these hydrolases are acidic and were detected exclusively in OMV. This suggests the presence of a molecular mechanism inBacteroidesresponsible for the selection of OMV proteins based on their charge. We propose that OMV contribute to the establishment and balance of the gut microbiota.

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The Antistaphylococcal Lysin, CF-301, Activates Key Host Factors in Human Blood To Potentiate Methicillin-ResistantStaphylococcus aureusBacteriolysis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02291-18 ◽

2019 ◽

Vol 63 (4) ◽

Cited By ~ 12

Author(s):

Chiara Indiani ◽

Karen Sauve ◽

Assaf Raz ◽

Wessam Abdelhady ◽

Yan Q. Xiong ◽

...

Keyword(s):

Human Serum ◽

Human Blood ◽

Hydrolytic Enzymes ◽

Host Factors ◽

Adjunctive Treatment ◽

Content Type ◽

Therapeutic Implications ◽

Antistaphylococcal Activity

ABSTRACTBacteriophage-derived lysins are cell-wall-hydrolytic enzymes that represent a potential new class of antibacterial therapeutics in development to address burgeoning antimicrobial resistance. CF-301, the lead compound in this class, is in clinical development as an adjunctive treatment to potentially improve clinical cure rates ofStaphylococcus aureusbacteremia and infective endocarditis (IE) when used in addition to antibiotics. In order to profile the activity of CF-301 in a clinically relevant milieu, we assessed itsin vitroactivity in human blood versus in a conventional testing medium (cation-adjusted Mueller-Hinton broth [caMHB]). CF-301 exhibited substantially greater potency (32 to ≥100-fold) in human blood versus caMHB in three standard microbiologic testing formats (e.g., broth dilution MICs, checkerboard synergy, and time-kill assays). We demonstrated that CF-301 acted synergistically with two key human blood factors, human serum lysozyme (HuLYZ) and human serum albumin (HSA), which normally have no nascent antistaphylococcal activity, against a prototypic methicillin-resistantS. aureus(MRSA) strain (MW2). Similarin vitroenhancement of CF-301 activity was also observed in rabbit, horse, and dog (but not rat or mouse) blood. Two well-established MRSA IE models in rabbit and rat were used to validate these findingsin vivoby demonstrating comparable synergistic efficacy with standard-of-care anti-MRSA antibiotics at >100-fold lower lysin doses in the rabbit than in the rat model. The unique properties of CF-301 that enable bactericidal potentiation of antimicrobial activity via activation of “latent” host factors in human blood may have important therapeutic implications for durable improvements in clinical outcomes of serious antibiotic-resistant staphylococcal infections.

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