Alan Decho

University of South Carolina | USC · Department of Environmental Health Sciences

The rise of antibiotic resistance, biofilm formation, and dormant bacterial populations poses serious global health threats. Synthetic antimicrobial peptide (AMP) mimics offer promising alternatives, though the impact of secondary structures in polymeric AMP mimics on antimicrobial efficacy is underexplored. This study investigates chirality-contro...

Democratizing genomic data science, including bioinformatics, can diversify the STEM workforce and may, in turn, bring new perspectives into the space sciences. In this respect, the development of education and research programs that bridge genome science with "place" and world-views specific to a given region are valuable for Indigenous students a...

Growing concerns exist regarding human ingestion of contaminated seafood that contains Vibrio biofilms on microplastics (MPs). One of the mechanisms enhancing biofilm related infections in humans is due to biofilm dispersion, a process that triggers release of bacteria from biofilms into the surrounding environment, such as the gastrointestinal tra...

Members of the archaeal order Caldarchaeales (previously the phylum Aigarchaeota) are poorly sampled and are represented in public databases by relatively few genomes. Additional representative genomes will help resolve their placement among all known members of Archaea and provide insights into their roles in the environment. In this study, we ana...

Aflatoxins, a family of fungal secondary metabolites, are toxic and carcinogenic compounds that pose an enormous threat to global food safety and agricultural sustainability. Specifically agricultural products in African, Southeast Asian and hot and humid regions of American countries suffer most damage from aflatoxin producing molds due to the ide...

We report facially amphiphilic bile acid-based antimicrobials with a broad spectrum of activity against both bacterial and fungal pathogens and negligible detrimental effects on mammalian cells. Two lead compounds eliminated dormant subpopulations of various bacterial species, unlike conventional antibiotics. The lead compounds were also effective...

Climate‐induced stressors, such as changes in temperature, salinity, and pH, contribute to the emergence of infectious diseases. These changes alter geographical constraint, resulting in increased Vibrio spread, exposure, and infection rates, thus facilitating greater Vibrio‐human interactions. Multiple efforts have been developed to predict Vibrio...

Facial amphiphilicity is an extraordinary chemical structure feature of a variety of antimicrobial peptides and polymers. Vast efforts have been dedicated to small molecular, macromolecular and dendrimer-like systems to mimic this highly preferred structure or conformation, including local facial amphiphilicity and global amphiphilicity. This work...

Marine bacteria often exist in biofilms as communities attached to surfaces, like plastic. Growing concerns exist regarding marine plastics acting as potential vectors of pathogenic Vibrio, especially in a changing climate. It has been generalized that Vibrio vulnificus and Vibrio parahaemolyticus often attach to plastic surfaces. Different strains...

Lava caves, tubes, and fumaroles in Hawai'i present a range of volcanic, oligotrophic environments from different lava flows and host unexpectedly high levels of bacterial diversity. These features provide an opportunity to study the ecological drivers that structure bacterial community diversity and assemblies in volcanic ecosystems and compare th...

Compared with single-network hydrogels, double-network hydrogels offer higher mechanical strength and toughness. Integrating useful functions into double-network hydrogels can expand the portfolios of the hydrogels. We report the preparation of double-network metallopolymer hydrogels with remarkable hydration, antifouling, and antimicrobial propert...

The Puquios of the Salar de Llamara in the Atacama Desert, northern Chile, is a system of small lakes that is characterized by evaporitic mineral deposition and that commonly hosts microbial communities. This region is known for its extreme aridity, solar irradiance, and temperature fluctuations. The Puquios are a highly diverse ecosystem with a va...

Chronic multisymptom illness (CMI) affects a subsection of elderly and war Veterans and is associated with systemic inflammation. Here, using a mouse model of CMI and a group of Gulf War (GW) Veterans’ with CMI we show the presence of an altered host resistome. Results show that antibiotic resistance genes (ARGs) are significantly altered in the CM...

This paper reports antimicrobial metallopolymers containing biodegradable polycaprolactone as the backbone with boronic acid and cobaltocenium as the side chain. While boronic acid promotes interactions with bacterial cells via boronolectin with lipopolysaccharides, cationic cobaltocenium facilitates the unique complexation with anionic β-lactam an...

Metals being released into the environment are posing an increasing risk to both environments and public health. Developing improved approaches to remove these metals from the environment is urgent. A current publication discovered that metal bioremediation was significantly improved by nanoparticles (NPs), and the remediation duration was shortene...

Chronic multi-symptom illness (CMI) affects a subsection of elderly and war veterans and is associated with systemic inflammation, chronic fatigue, pain and neuroinflammation. We showed previously that an altered gut microbiome-inflammation axis aids to the symptom reporting and persistence. Here, a mouse model of CMI and a group of Gulf War vetera...

Bacteria efficiently take up small organic molecules and ions. However, the internalization of particulate forms, specifically nanoparticles (NPs) has been understudied and is a newly-emerging area of interest. However, determination of true cellular internalization is challenging owing to the difficulty of separating the aqueous phase from bacteri...

Objectives The aim of this study was to examine how the concentrated delivery of less-effective antibiotics, such as the β-lactam penicillin-G, by linkage to nanoparticles (NPs) could influence the killing efficiency against various pathogenic bacteria including methicillin-resistant-Staphylococcus aureus (MRSA) and other multi-drug resistant (MDR)...

Quorum sensing (QS), a type of chemical communication, allows bacteria to sense and coordinate activities in natural biofilm communities using N-acyl homoserine lactones (AHLs) as one type of signaling molecule. For AHL-based communication to occur, bacteria must produce and recognize the same signals, which activate similar genes in different spec...

New antimicrobial agents are needed to address ever-increasing antimicrobial resistance and a growing epidemic of infections caused by multidrug resistant pathogens. We design nanostructured antimicrobial copolymers containing multicyclic natural products that bear facial amphiphilicity. Bile acid based macromolecular architectures of these nanostr...

Polyvinylpyrrolidone (PVP) coated iron oxide nanoparticles (NPs) were used to explore the potential for improved bioremediation of metals by interaction with the Gram-negative bacterium Halomonas sp. The combined approach improved metal removal and shortened metal remediation times (approx. 100% removal of Pb after 24 h, of Cd after 48 h) compared...

Bacterial infections and antibiotic resistance, particularly by Gram-negative pathogens, have become a global healthcare crisis. We report the design of a class of cationic antimicrobial polymers that cluster local facial amphiphilicity from repeating units to enhance interactions with bacterial membranes without requiring a globally conformational...

Over-prescription and improper use of antibiotics has led to the emergence of bacterial resistance, posing a major threat to public health. There has been significant interest in the development of alternative therapies and agents to combat antibiotic resistance. We report the preparation of recyclable magnetic iron oxide nanoparticles grafted with...

Bacterial infections have become a global issue that requires urgent attention, particularly regarding to emergence of multidrug resistant bacteria. We developed quaternary amine-containing antimicrobial poly(bile acid)s that contain a hydrophobic core of lithocholic acid in the main-chain. Interestingly, by choosing appropriate monomers, these cat...

Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS) provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to...

Bacterial infections, particularly by Gram-negative pathogens, have become a serious threat to global healthcare due to the diminishing effectiveness of existing antibiotics. We report a non-traditional therapy to combine three components in one macromolecular system, in which boronic acid adheres to peptidoglycan or lipopolysaccharide via boron-po...

Vibrio gazogenes ATCC 43942 has the potential to synthesize a plethora of metabolites which are of clinical and agricultural significance in response to environmental triggers. The complete genomic sequence of Vibrio gazogenes ATCC 43942 is reported herein, contributing to the knowledge base of strains in the Vibrio genus.

Crude oil and its water-accommodated fractions (WAF) have the potential to cause catastrophic damage to aquatic ecosystems when released. A new nanomaterial (NM), composed of polyvinylpyrrolidone-coated iron oxide, has been successfully used to remediate oil-contaminated waters. In this study, the toxicity of these NMs, crude oil WAF, and their mix...

Microbial cells (i.e., bacteria, archaea, microeukaryotes) in oceans secrete a diverse array of large molecules, collectively called extracellular polymeric substances (EPSs) or simply exopolymers. These secretions facilitate attachment to surfaces that lead to the formation of structured ‘biofilm’ communities. In open-water environments, they also...

Aflatoxin is a mycotoxin and a secondary metabolite, and the most potent known liver carcinogen that contaminates several important crops, and represents a significant threat to public health and the economy. Available approaches reported thus far have been insufficient to eliminate this threat, and therefore provide the rational to explore novel m...

Quorum sensing (QS) and other forms of chemical sensing are now realized to be important processes regulating group behaviors of microbial cells involved in health-related pathogenic infections, commensal gut flora, as well as those in natural environments. The physical migration of molecules from a sender-cell to a receiver-cell most often occurs...

We report antibacterial, anti-biofilm and biocompatible properties of surface-immobilized, quaternary ammonium-containing, resin acid-derived compounds and polycations that are known to be efficient antimicrobial agents with minimum toxicities to mammalian cells. Surface immobilization was carried out by the employment of two robust, efficient chem...

Metallopolymers combine a processable, versatile organic polymeric skeleton with functional metals, providing multiple functions and methodologies in materials science. Taking advantage of cationic cobaltocenium as the key building block, organogels could be simply switched to hydrogels via a highly efficient ion exchange. With the unique ionic com...

Antibiotics were once the golden bullet to constrain infectious bacteria. However, the rapid and continuing emergence of antibiotic resistance (AR) among infectious microbial pathogens has questioned the future utility of antibiotics. This dilemma has recently fueled the marriage of the disparate fields of nanochemistry and antibiotics. Nanoparticl...

Bacteria are essential components of all natural and many engineered systems. The most active fractions of bacteria are now recognized to occur as biofilms, where cells are attached and surrounded by a secreted matrix of “sticky” extracellular polymeric substances. Recent investigations have established that significant accumulation of nanoparticle...

The alarming spread of bacterial resistance to traditional antibiotics has warranted the study of alternative antimicrobial agents. Quorum sensing (QS) is a chemical cell-to-cell communication mechanism utilized by bacteria to coordinate group behaviors and establish infections. QS is integral to bacterial survival, and therefore provides a unique...

A cell-lysate extract based assay reagent for detecting quorum sensing signals is generally provided, along with methods of making and using the same. The assay reagent generally includes a cell-lysate extract formed from a biosensor bacterium (e.g., Agrobacterium tumefaciens NTL4 (pCF218)(pCF372)) and a detecting substrate (e.g., an absorbance-bas...

This work reports on a new combination of recyclable magnetic nanoparticles, polymers and antibiotics that show increased effectiveness in combating bacterial infections. The direct-coprecipitation of iron salts strategy was used to generate superparamagnetic nanoparticles with a saturation magnetization of 59.5 emu/g. A silica coating was applied...

Antibiotic-resistant bacterial infections are a vexing global health problem and have rendered ineffective many previously-used antibiotics. Here we demonstrate that antibiotic-linkage to surface-functionalized silica nanoparticles (sNP) significantly enhances their effectiveness against Escherichia coli, and Staphylococcus aureus, and even methici...

Methicillin-resistant Staphylococcus aureus (MRSA), a complex of multidrug resistant Gram-positive bacterial strains, has proven especially problematic in both hospital and community-settings, resulting in increased mortality rates and hospitalization costs. Emergence of resistance even to vancomycin, the standard reference for MRSA treatment, buil...

While environmental biofilms have recently been implicated as a potential major sink for nanoparticles (NPs), the mechanisms of interactions remain largely unknown. Polysaccharides are a common component of biofilm extracellular polymeric substances (EPS) and an initial point of contact for NPs in early NP-biofilm interactions. In this study, the s...

Bacteria are now becoming more resistant to most conven-tional antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA), a complex of multidrug resistant Gram-positive bacterial strains, has proven especially problematic in both hospital and community-settings by deactivating convention-al β-lactam antibiotics, including penicillins, cephalo...

Microspatial arrangements of sulfate-reducing microorganisms (SRM) in surface microbial mats (~1.5 mm) forming open marine stromatolites were investigated. Previous research revealed three different mat types associated with these stromatolites, each with a unique petrographic signature. Here we focused on comparing “non-lithifying” (Type-1) and “l...

The process of biofilm formation has knowingly, and even unsuspectingly, baffled scientists for almost as long as the field of microbiology itself has existed. This Special Issue of the International Journal of Molecular Sciences (IJMS) specifically addresses an important component of the biofilm, the extracellular matrix. This matrix forms the pro...

This work reports the distribution of negatively charged, gold core nanoparticles in a model marine estuary as a function of time. A single dose of purified polystyrene sulfonate (PSS) coated gold nanorods was added to a series of three replicate estuarine mesocosms to emulate an abrupt nanoparticle release event to a tidal creek of a Spartina-domi...

A cell-lysate extract based assay reagent for detecting quorum sensing signals is generally provided, along with methods of making and using the same. The assay reagent generally includes a cell-lysate extract formed from a biosensor bacterium (e.g., Agrobacterium tumefaciens NTL4 (pCF218)(pCF372)) and a detecting substrate (e.g., an absorbance-bas...

Prokaryota in natural environments form biofilms, which are benthic assemblages of a variety of microorganisms embedded within their extracellular mucilage. Biofilms are firmly attached to surfaces such as aquatic sediments. Quorum sensing by the many microbes in a biofilm is collective decision making and cooperation in responding to internal and...

We prepared a class of novel cationic polymers as antimicrobial agents: quaternary ammonium-containing poly(N,N-dimethylaminoethyl methacrylate) with natural rosin as the pendant group (PDMAEMA-g-rosin). Different from most other amphipathic antimicrobial polymeric systems reported in the literature, our approach sandwiched the hydrophilic cationic...

A study was conducted to investigate the role of nanoparticle (NP) surface functionalization/charge on their uptake by biofilms. Biofilms, bacterial colonies attached to surfaces via extracellular polymers, are effective at removing suspended nanomaterials from the aqueous phase. However, the mechanisms regulating particle uptake are unknown. Here,...

Ecotoxicology research is using many methods for engineered nanomaterials (ENMs), but the collective experience from researchers has not been documented. This paper reports the practical issues for working with ENMs and suggests nano-specific modifications to protocols. The review considers generic practical issues, as well as specific issues for a...

We report novel robust resin acid-derived antimicrobial agents that exhibit excellent antimicrobial activities against a broad spectrum of bacteria (6 Gram-positive and 7 Gram-negative) with selective lysis of microbial membranes over mammalian membranes. Our results indicate that hydrophobicity and unique structures of resin acids can be determini...

Chemical signaling is a multidisciplinary topic that combines the relevant terminologies of microbiology, chemical ecology, and chemistry. QS is a process where cells produce molecular cues that are released outside the cell, traverse the extra-cellular environment mostly by diffusion, and are perceived by other cells in proximity, or by the same....

SynonymsCapsule; Exopolymers; Exopolysaccharide; Microbial secretions; SlimeDefinitionExtracellular polymeric substances (EPS) are molecules having a range of sizes, compositions, and chemical properties that are produced and secreted by bacteria and other microorganisms, and contribute to the cell adaptability, resiliency, and functional roles in...

Chemical communication in bacteria, sometimes called quorum sensing, is a fundamental microbial process that is based on the exchange of molecular signals between cells. The signaling molecules involved in this process are thermodynamically unstable in some environments and their degradation affects microbial communication. This work reports the ox...

Due to the presence of inhibitors such as extracellular polymeric substances (EPSs) and salts, most microbial mat studies have relied on harsh methods of direct DNA extraction that result in DNA fragments too small for large-insert vector cloning. High molecular weight (HMW) DNA is crucial in functional metagenomic studies, because large fragments...

The unique geochemical coupling of organic molecules and mineral CaCO3 provides a fluorescence signature detectable using conventional confocal scanning laser microscopy (CSLM). The surface microbial mats of open-water marine stromatolites (Bahamas) exist in a continuum of states ranging from a Type 1 (i.e., nonlithifying) to Type 2 (i.e., lithifie...