Affordable oral health care: dental biofilm disruption using chloroplast made enzymes with chewing gum delivery

Genome editing in angiosperm chloroplasts: targeted DNA double-strand break and base editing

Chloroplasts are organelles that are derived from a photosynthetic bacterium and have their own genome. Genome editing is a recently developing technology that allows for specific modifications of target sequences. The first successful application of genome editing in chloroplasts was reported in 2021, and since then, this research field has been expanding. Although the chloroplast genome of several dicot species can be stably modified by a conventional method, which involves inserting foreign DNAs into the chloroplast genome via homologous recombination, genome editing offers several advantages over this method. In this review, we introduce genome editing methods targeting the chloroplast genome and describe their advantages and limitations. So far, CRISPR/Cas systems are inapplicable for editing the chloroplast genome because guide RNAs, unlike proteins, cannot be efficiently delivered into chloroplasts. Therefore, protein-based enzymes are used to edit the chloroplast genome. These enzymes contain a chloroplast-transit peptide, the DNA-binding domain of transcription activator-like effector nuclease (TALEN), or a catalytic domain that induces DNA modifications. To date, genome editing methods can cause DNA double-strand break or introduce C:G-to-T:A and A:T-to-G:C base edits at or near the target sequence. These methods are expected to contribute to basic research on the chloroplast genome in many species and to be fundamental methods of plant breeding utilizing the chloroplast genome.

Molecular farming for sustainable production of clinical-grade antimicrobial peptides

Antimicrobial peptides (AMPs) are emerging as next-generation therapeutics due to their broad-spectrum activity against drug-resistant bacterial strains and their ability to eradicate biofilms, modulate immune responses, exert anti-inflammatory effects and improve disease management. They are produced through solid-phase peptide synthesis or in bacterial or yeast cells. Molecular farming, i.e. the production of biologics in plants, offers a low-cost, non-toxic, scalable and simple alternative platform to produce AMPs at a sustainable cost. In this review, we discuss the advantages of molecular farming for producing clinical-grade AMPs, advances in expression and purification systems and the cost advantage for industrial-scale production. We further review how 'green' production is filling the sustainability gap, streamlining patent and regulatory approvals and enabling successful clinical translations that demonstrate the future potential of AMPs produced by molecular farming. Finally, we discuss the regulatory challenges that need to be addressed to fully realize the potential of molecular farming-based AMP production for therapeutics.

Effect of mutanase and dextranase on biofilms of cariogenic bacteria: A systematic review of in vitro studies

Matrix-degrading enzymes are promising non-biocidal adjuncts to dental biofilm control and caries prevention. By disrupting the biofilm matrix structure, enzymes may prevent biofilm formation or disperse established biofilms without compromising the microbial homeostasis in the mouth. This study reviewed whether treatment with mutanase and/or dextranase inhibits cariogenic biofilm growth and/or removes cariogenic biofilms in vitro. An electronic search was conducted in PubMed, EMBASE, Scopus, Web of Science, Cochrane, and LIVIVO databases. Manual searches were performed to identify additional records. Studies that quantitatively measured the effect of mutanase and/or dextranase on the inhibition/removal of in vitro cariogenic biofilms were considered eligible for inclusion. Out of 809 screened records, 34 articles investigating the effect of dextranase (n = 23), mutanase (n = 10), and/or combined enzyme treatment (n = 7) were included in the review. The overall risk of bias of the included studies was moderate. Most investigations used simple biofilm models based on one or few bacterial species and employed treatment times ≥30 min. The current evidence suggests that mutanase and dextranase, applied as single or combined treatment, are able to both inhibit and remove in vitro cariogenic biofilms. The pooled data indicate that enzymes are more effective for biofilm inhibition than removal, and an overall higher effect of mutanase compared to dextranase was observed.

Drug-loaded adhesive microparticles for biofilm prevention on oral surfaces

The oral cavity, a warm and moist environment, is prone to the proliferation of microorganisms like Candida albicans (C. albicans), which forms robust biofilms on biotic and abiotic surfaces, leading to challenging infections. These biofilms are resistant to conventional treatments due to their resilience against antimicrobials and immune responses. The dynamic nature of the oral cavity, including the salivary flow and varying surface properties, complicates the delivery of therapeutic agents. To address these challenges, we introduce dendritic microparticles engineered for enhanced adhesion to dental surfaces and effective delivery of antifungal agents and antibiofilm enzymes. These microparticles are fabricated using a water-in-oil-in-water emulsion process involving a blend of poly(lactic-co-glycolic acid) (PLGA) random copolymer (RCP) and PLGA-b-poly(ethylene glycol) (PLGA-b-PEG) block copolymer (BCP), resulting in particles with surface dendrites that exhibit strong adhesion to oral surfaces. Our study demonstrates the potential of these adhesive microparticles for oral applications. The adhesion tests on various oral surfaces, including dental resin, hydroxyapatite, tooth enamel, and mucosal tissues, reveal superior adhesion of these microparticles compared to conventional spherical ones. Furthermore, the release kinetics of nystatin from these microparticles show a sustained release pattern that can kill C. albicans. The biodegradation of these microparticles on tooth surfaces and their efficacy in preventing fungal biofilms have also been demonstrated. Our findings highlight the effectiveness of adhesive microparticles in delivering therapeutic agents within the oral cavity, offering a promising approach to combat biofilm-associated infections.

The Effect of Enzymatic Treatment with Mutanase, Beta-Glucanase, and DNase on a Saliva-Derived Biofilm Model

INTRODUCTION

The dental biofilm matrix is an important determinant of virulence for caries development and comprises a variety of extracellular polymeric substances that contribute to biofilm stability. Enzymes that break down matrix components may be a promising approach to caries control, and in light of the compositional complexity of the dental biofilm matrix, treatment with multiple enzymes may enhance the reduction of biofilm formation compared to single enzyme therapy. The present study investigated the effect of the three matrix-degrading enzymes mutanase, beta-glucanase, and DNase, applied separately or in combinations, on biofilm prevention and removal in a saliva-derived in vitro-grown model.

METHODS

Biofilms were treated during growth to assess biofilm prevention or after 24 h of growth to assess biofilm removal by the enzymes. Biofilms were quantified by crystal violet staining and impedance-based real-time cell analysis, and the biofilm structure was visualized by confocal microscopy and staining of extracellular DNA (eDNA) and polysaccharides.

RESULTS

The in vitro model was dominated by Streptococcus spp., as determined by 16S rRNA gene amplicon sequencing. All tested enzymes and combinations had a significant effect on biofilm prevention, with reductions of >90% for mutanase and all combinations including mutanase. Combined application of DNase and beta-glucanase resulted in an additive effect (81.0% ± 1.3% SD vs. 36.9% ± 21.9% SD and 48.2% ± 14.9% SD). For biofilm removal, significant reductions of up to 73.2% ± 5.5% SD were achieved for combinations including mutanase, whereas treatment with DNase had no effect. Glucans, but not eDNA decreased in abundance upon treatment with all three enzymes.

CONCLUSION

Multi-enzyme treatment is a promising approach to dental biofilm control that needs to be validated in more diverse biofilms.

Delivery of biologics: Topical administration

Biologics are unaffordable to a large majority of the global population because of prohibitively expensive fermentation systems, purification and the requirement for cold chain for storage and transportation. Limitations of current production and delivery systems of biologics were evident during the recent pandemic when <2.5% of vaccines produced were available to low-income countries and ∼19 million doses were discarded in Africa due to lack of cold-chain infrastructure. Among FDA-approved biologics since 2015, >90% are delivered using invasive methods. While oral or topical drugs are highly preferred by patients because of their affordability and convenience, only two oral drugs have been approved by FDA since 2015. A newly launched oral biologic costs only ∼3% of the average cost of injectable biologics because of the simplified regulatory approval process by elimination of prohibitively expensive fermentation, purification, cold storage/transportation. In addition, the cost of developing a new biologic injectable product (∼$2.5 billion) has been dramatically reduced through oral or topical delivery. Topical delivery has the unique advantage of targeted delivery of high concentration protein drugs, without getting diluted in circulating blood. However, only very few topical drugs have been approved by the FDA. Therefore, this review highlights recent advances in oral or topical delivery of proteins at early or advanced stages of human clinical trials using chewing gums, patches or sprays, or nucleic acid drugs directly, or in combination with, nanoparticles and offers future directions.

The lyophilized chloroplasts store synthetic DARPin G3 as bioactive encapsulated organelles

BACKGROUND

The high cost of fermentation, purification, cold storage and transportation, short shelf life, and sterile delivery methods of biopharmaceuticals, is a matter for producers and consumers as well. Since the FDA has now approved plant cells for large-scale, cost-effective biopharmaceutical production, the isolation and lyophilization of transplastomic chloroplasts can cover concerns about limitations. DARPins are engineered small single-domain proteins that have been selected to bind to HER2 with high affinity and specificity. HER2 is an oncogene involved in abnormal cell growth in some cancers and the target molecule for cancer immunotherapy.

RESULTS

In this study, we reported the prolonged stability and functionality of DARPin G3 in lyophilized transplastomic tobacco leaves and chloroplasts. Western blot analysis of lyophilized leaves and chloroplasts stored at room temperature for up to nine months showed that the DARPin G3 protein was stable and preserved proper folding. Lyophilization of leaves and isolated chloroplasts increased DARPin G3 protein concentrations by 16 and 32-fold, respectively. The HER2-binding assay demonstrated that the chloroplast-made DARPin G3 can maintain its stability and binding activity without any affinity drop in lyophilized leaf materials throughout this study for more than nine months at room temperature.

CONCLUSION

Lyophilization of chloroplasts expressing DARPin G3 would further reduce costs and simplify downstream processing, purification, and storage. Compressed packages of lyophilized chloroplasts were much more effective than lyophilized transplastomic leaves considering occupied space and downstream extraction and purification of DARPin G3 after nine months. These methods facilitate any relevant formulation practices for these compounds to meet any demand-oriented needs.

Dental Medicine and Engineering Unite to Transform Oral Health Innovations

This perspective article urges the academic community to adopt a coordinated approach uniting dental medicine and engineering to support research, training, and entrepreneurship to address the unmet needs and spur oral health care innovations. We describe a new interschool institute that brings together dentists, scientists and engineers, resources, and a training program dedicated for affordable oral health care innovations, which may serve as a template for dental medicine-engineering integration.

Drug delivery strategies for antibiofilm therapy

Although new antibiofilm agents have been developed to prevent and eliminate pathogenic biofilms, their widespread clinical use is hindered by poor biocompatibility and bioavailability, unspecific interactions and insufficient local concentrations. The development of innovative drug delivery strategies can facilitate penetration of antimicrobials through biofilms, promote drug dispersal and synergistic bactericidal effects, and provide novel paradigms for clinical application. In this Review, we discuss the potential benefits of such emerging techniques for improving the clinical efficacy of antibiofilm agents, as well as highlighting the existing limitations and future prospects for these therapies in the clinic.

Plant-based biopharmaceutical engineering

Plants can be engineered to recombinantly produce high-quality proteins such as therapeutic proteins and vaccines, also known as molecular farming. Molecular farming can be established in various settings with minimal cold-chain requirements and could thus ensure rapid and global-scale deployment of biopharmaceuticals, promoting equitable access to pharmaceuticals. State of the art plant-based engineering relies on rationally assembled genetic circuits, engineered to enable the high-throughput and rapid expression of multimeric proteins with complex post-translational modifications. In this Review, we discuss the design of expression hosts and vectors, including Nicotiana benthamiana, viral elements and transient expression vectors, for the production of biopharmaceuticals in plants. We examine engineering of post-translational modifications and highlight the plant-based expression of monoclonal antibodies and nanoparticles, such as virus-like particles and protein bodies. Techno-economic analyses suggest a cost advantage of molecular farming compared with mammalian cell-based protein production systems. However, regulatory challenges remain to be addressed to enable the widespread translation of plant-based biopharmaceuticals.

Genetic Engineering of Potato (Solanum tuberosum) Chloroplasts Using the Small Synthetic Plastome "Mini-Synplastome"

In the rapidly expanding field of synthetic biology, chloroplasts represent attractive targets for installation of valuable genetic circuits in plant cells. Conventional methods for engineering the chloroplast genome (plastome) have relied on homologous recombination (HR) vectors for site-specific transgene integration for over 30 years. Recently, episomal-replicating vectors have emerged as valuable alternative tools for genetic engineering of chloroplasts. With regard to this technology, in this chapter we describe a method for engineering potato (Solanum tuberosum) chloroplasts to generate transgenic plants using the small synthetic plastome (mini-synplastome). In this method, the mini-synplastome is designed for Golden Gate cloning for easy assembly of chloroplast transgene operons. Mini-synplastomes have the potential to accelerate plant synthetic biology by enabling complex metabolic engineering in plants with similar flexibility of engineered microorganisms.

Biofilm ecology associated with dental caries: Understanding of microbial interactions in oral communities leads to development of therapeutic strategies targeting cariogenic biofilms

A biofilm is a sessile community characterized by cells attached to the surface and organized into a complex structural arrangement. Dental caries is a biofilm-dependent oral disease caused by infection with cariogenic pathogens, such as Streptococcus mutans, and associated with frequent exposure to a sugar-rich diet and poor oral hygiene. The virulence of cariogenic biofilms is often associated with the spatial organization of S. mutans enmeshed with exopolysaccharides on tooth surfaces. However, in the oral cavity, S. mutans does not act alone, and several other microbes contribute to cariogenic biofilm formation. Microbial communities in cariogenic biofilms are spatially organized into complex structural arrangements of various microbes and extracellular matrices. The balance of microbiota diversity with reduced diversity and a high proportion of acidogenic-aciduric microbiota within the biofilm is closely related to the disease state. Understanding the characteristics of polymicrobial biofilms and the association of microbial interactions within the biofilm (e.g., symbiosis, cooperation, and competition) in terms of their potential role in the pathogenesis of oral disease would help develop new strategies for interventions in virulent biofilm formation.

Interkingdom assemblages in human saliva display group-level surface mobility and disease-promoting emergent functions

Fungi and bacteria form multicellular biofilms causing many human infections. How such distinctive microbes act in concert spatiotemporally to coordinate disease-promoting functionality remains understudied. Using multiscale real-time microscopy and computational analysis, we investigate the dynamics of fungal and bacterial interactions in human saliva and their biofilm development on tooth surfaces. We discovered structured interkingdom assemblages displaying emergent functionalities to enhance collective surface colonization, survival, and growth. Further analyses revealed an unexpected group-level surface mobility with coordinated “leaping-like” and “walking-like” motions while continuously growing. These mobile groups of growing cells promote rapid spatial spreading of both species across surfaces, causing more extensive tooth decay. Our findings show multicellular interkingdom assemblages acting like supraorganisms with functionalities that cannot be achieved without coassembly.

Fungi and bacteria often engage in complex interactions, such as the formation of multicellular biofilms within the human body. Knowledge about how interkingdom biofilms initiate and coalesce into higher-level communities and which functions the different species carry out during biofilm formation remain limited. We found native-state assemblages of Candida albicans (fungi) and Streptococcus mutans (bacteria) with highly structured arrangement in saliva from diseased patients with childhood tooth decay. Further analyses revealed that bacterial clusters are attached within a network of fungal yeasts, hyphae, and exopolysaccharides, which bind to surfaces as a preassembled cell group. The interkingdom assemblages exhibit emergent functions, including enhanced surface colonization and growth rate, stronger tolerance to antimicrobials, and improved shear resistance, compared to either species alone. Notably, we discovered that the interkingdom assemblages display a unique form of migratory spatial mobility that enables fast spreading of biofilms across surfaces and causes enhanced, more extensive tooth decay. Using mutants, selective inactivation of species, and selective matrix removal, we demonstrate that the enhanced stress resistance and surface mobility arise from the exopolymeric matrix and require the presence of both species in the assemblage. The mobility is directed by fungal filamentation as hyphae extend and contact the surface, lifting the assemblage with a “forward-leaping motion.” Bacterial cell clusters can “hitchhike” on this mobile unit while continuously growing, to spread across the surface three-dimensionally and merge with other assemblages, promoting community expansion. Together, our results reveal an interkingdom assemblage in human saliva that behaves like a supraorganism, with disease-causing emergent functionalities that cannot be achieved without coassembly.

LsNRL4 enhances photosynthesis and decreases leaf angles in lettuce

Lettuce (Lactuca sativa) is one of the most important vegetables worldwide and an ideal plant for producing protein drugs. Both well-functioning chloroplasts that perform robust photosynthesis and small leaf angles that enable dense planting are essential for high yields. In this study, we used an F2 population derived from a cross between a lettuce cultivar with pale-green leaves and large leaf angles to a cultivar with dark-green leaves and small leaf angles to clone LsNRL4, which encodes an NPH3/RPT2-Like (NRL) protein. Unlike other NRL proteins in lettuce, the LsNRL4 lacks the BTB domain. Knockout mutants engineered using CRISPR/Cas9 and transgenic lines overexpressing LsNRL4 verified that LsNRL4 contributes to chloroplast development, photosynthesis and leaf angle. The LsNRL4 gene was not present in the parent with pale-green leaves and enlarged leaf angles. Loss of LsNRL4 results in the enlargement of chloroplasts, decreases in the amount of cellular space allocated to chloroplasts and defects in secondary cell wall biosynthesis in lamina joints. Overexpressing LsNRL4 significantly improved photosynthesis and decreased leaf angles. Indeed, the plant architecture of the overexpressing lines is ideal for dense planting. In summary, we identified a novel NRL gene that enhances photosynthesis and influences plant architecture. Our study provides new approaches for the breeding of lettuce that can be grown in dense planting in the open field or in modern plant factories. LsNRL4 homologues may also be used in other crops to increase photosynthesis and improve plant architecture.

A recombinant subunit vaccine candidate produced in plants elicits neutralizing antibodies against SARS-CoV-2 variants in macaques

Since the outbreak of the coronavirus disease (COVID) pandemic in 2019, the development of effective vaccines to combat the infection has been accelerated. With the recent emergence of highly transmissible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOC), there are concerns regarding the immune escape from vaccine-induced immunity. Hence an effective vaccine against VOC with a potent immune response is required. Our previous study confirmed that the two doses of the plant-produced receptor-binding domain (RBD) of SARS-CoV-2 fused with the Fc region of human IgG1, namely Baiya SARS-CoV-2 Vax 1, showed high immunogenicity in mice and monkeys. Here, we aimed to evaluate the immunogenicity of a three-dose intramuscular injection of Baiya SARS-CoV-2 Vax 1 on days 0, 21, and 133 in cynomolgus monkeys. At 14 days after immunization, blood samples were collected to determine RBD-specific antibody titer, neutralizing antibody, and pseudovirus neutralizing antibody titers. Immunized monkeys developed significantly high levels of antigen-specific antibodies against SARS-CoV-2 compared to the control group. Interestingly, the sera collected from immunized monkeys also showed a neutralizing antibody response against the SARS-CoV-2 VOCs; Alpha, Beta, Gamma, Delta, and Omicron. These findings demonstrate that a three-dose regimen of Baiya SARS-CoV-2 Vax 1 vaccine elicits neutralizing immune response against SARS-CoV-2 variants.

Debulking different Corona (SARS-CoV-2 delta, omicron, OC43) and Influenza (H1N1, H3N2) virus strains by plant viral trap proteins in chewing gums to decrease infection and transmission

Because oral transmission of SARS-CoV-2 is 3-5 orders of magnitude higher than nasal transmission, we investigated debulking of oral viruses using viral trap proteins (CTB-ACE2, FRIL) expressed in plant cells, delivered through the chewing gum. In omicron nasopharyngeal (NP) samples, the microbubble count (based on N-antigen) was significantly reduced by 20 μg of FRIL (p < 0.0001) and 0.925 μg of CTB-ACE2 (p = 0.0001). Among 20 delta or omicron NP samples, 17 had virus load reduced below the detection level of spike protein in the RAPID assay, after incubation with the CTB-ACE2 gum powder. A dose-dependent 50% plaque reduction with 50-100 ng FRIL or 600-800 μg FRIL gum against Influenza strains H1N1, H3N2, and Coronavirus HCoV-OC43 was observed with both purified FRIL, lablab bean powder or gum. In electron micrographs, large/densely packed clumps of overlapping influenza particles and FRIL protein were observed. Chewing simulator studies revealed that CTB-ACE2 release was time/dose-dependent and release was linear up to 20 min chewing. Phase I/II placebo-controlled, double-blinded clinical trial (IND 154897) is in progress to evaluate viral load in saliva before or after chewing CTB-ACE2/placebo gum. Collectively, this study advances the concept of chewing gum to deliver proteins to debulk oral viruses and decrease infection/transmission.

Debulking SARS-CoV-2 in saliva using angiotensin converting enzyme 2 in chewing gum to decrease oral virus transmission and infection

To advance a novel concept of debulking virus in the oral cavity, the primary site of viral replication, virus-trapping proteins CTB-ACE2 were expressed in chloroplasts and clinical-grade plant material was developed to meet FDA requirements. Chewing gum (2 g) containing plant cells expressed CTB-ACE2 up to 17.2 mg ACE2/g dry weight (11.7% leaf protein), have physical characteristics and taste/flavor like conventional gums, and no protein was lost during gum compression. CTB-ACE2 gum efficiently (>95%) inhibited entry of lentivirus spike or VSV-spike pseudovirus into Vero/CHO cells when quantified by luciferase or red fluorescence. Incubation of CTB-ACE2 microparticles reduced SARS-CoV-2 virus count in COVID-19 swab/saliva samples by >95% when evaluated by microbubbles (femtomolar concentration) or qPCR, demonstrating both virus trapping and blocking of cellular entry. COVID-19 saliva samples showed low or undetectable ACE2 activity when compared with healthy individuals (2,582 versus 50,126 ΔRFU; 27 versus 225 enzyme units), confirming greater susceptibility of infected patients for viral entry. CTB-ACE2 activity was completely inhibited by pre-incubation with SARS-CoV-2 receptor-binding domain, offering an explanation for reduced saliva ACE2 activity among COVID-19 patients. Chewing gum with virus-trapping proteins offers a general affordable strategy to protect patients from most oral virus re-infections through debulking or minimizing transmission to others.

Mini-synplastomes for plastid genetic engineering

In the age of synthetic biology, plastid engineering requires a nimble platform to introduce novel synthetic circuits in plants. While effective for integrating relatively small constructs into the plastome, plastid engineering via homologous recombination of transgenes is over 30 years old. Here we show the design-build-test of a novel synthetic genome structure that does not disturb the native plastome: the 'mini-synplastome'. The mini-synplastome was inspired by dinoflagellate plastome organization, which is comprised of numerous minicircles residing in the plastid instead of a single organellar genome molecule. The first mini-synplastome in plants was developed in vitro to meet the following criteria: (i) episomal replication in plastids; (ii) facile cloning; (iii) predictable transgene expression in plastids; (iv) non-integration of vector sequences into the endogenous plastome; and (v) autonomous persistence in the plant over generations in the absence of exogenous selection pressure. Mini-synplastomes are anticipated to revolutionize chloroplast biotechnology, enable facile marker-free plastid engineering, and provide an unparalleled platform for one-step metabolic engineering in plants.

A Pair of "ACEs"

The emergence of the COVID-19 viral pandemic has generated a renewed interest in pharmacologic agents that target the renin angiotensin system (RAS). Angiotensin-converting enzyme 1 (ACE1) inhibitors decrease the synthesis of angiotensin II (Ang II) from its precursor angiotensin I and inhibit the breakdown of bradykinin, while Ang II receptor blockers antagonize the action of Ang II at the receptor level downstream. The actions of both classes of drugs lead to vasodilation, a blunting of sympathetic drive and a reduction in aldosterone release, all beneficial effects in hypertension and congestive heart failure. ACE2 cleaves the vasoconstrictor Ang II to produce the anti-inflammatory cytoprotective angiotensin 1-7 (Ang 1-7) peptide, which functions through the G protein-coupled receptor MAS to counteract the pathophysiologic effects induced by Ang II via its receptors, including vasoconstriction, inflammation, hypercoagulation, and fibrosis. SARS-CoV-2 enters human cells by binding ACE2 on the cell surface, decreases ACE2 activity, competes for ACE2 receptor-binding sites, and shifts the RAS toward an overexpression of Ang II, accounting for many of the deleterious effects of the virus. Thus, there is great interest in developing recombinant ACE2 as a therapeutic for prevention or treatment of COVID-19. Notably, ACE2 is highly expressed in the oral cavity, and saliva and dorsum of the tongue are major reservoirs of SARS-CoV-2. Cost-effective methods to debulk the virus in the oral cavity may aid in the prevention of viral spread. Here we review the pharmacology of targeted small molecule inhibitors of the RAS and discuss novel approaches to employing ACE2 as a therapeutic for COVID-19.

Combating Biofilm by Targeting Its Formation and Dispersal Using Gallic Acid against Single and Multispecies Bacteria Causing Dental Plaque

Exploring biological agents to control biofilm is a vital alternative in combating pathogenic bacteria that cause dental plaque. This study was focused on antimicrobial, biofilm formation and biofilm dispersal efficacy of Gallic acid (GA) against bacteria, including Proteus spp., Escherichia coli, Pseudomonas spp., Salmonella spp., Streptococcus mutans, and Staphylococcus aureus and multispecies bacteria. Biofilm was qualitatively and quantitatively assessed by crystal violet assay, florescence microscopy (bacterial biomass (µm²), surface coverage (%)) and extracellular polymeric substances (EPS). It was exhibited that GA (1-200 mg/L) can reduce bacterial growth. However, higher concentrations (100-200 mg/L) markedly reduced (86%) bacterial growth and biofilm formation (85.5%), while GA did not exhibit any substantial dispersal effects on pre-formed biofilm. Further, GA (20-200 mg/L) exhibited 93.43% biomass reduction and 88.6% (p < 0.05) EPS (polysaccharide) reduction. Microscopic images were processed with BioImageL software. It was revealed that biomass surface coverage was reduced to 2% at 200 mg/L of GA and that 13,612 (µm²) biomass was present for control, while it was reduced to 894 (µm²) at 200 mg/L of GA. Thus, this data suggest that GA have antimicrobial and biofilm control potential against single and multispecies bacteria causing dental plaque.