Characterization and assessment of barnacle larval settlement-inducing activity of extracellular polymeric substances isolated from marine biofilm bacteria

Genetically engineered phages and engineered phage-derived enzymes to destroy biofilms of antibiotics resistance bacteria

"An impregnable stronghold where one or more warrior clans can evade enemy attacks" may serve as a description of bacterial biofilm on a smaller level than human conflicts. Consider this hypothetical conflict: who would emerge victorious? The occupants of secure trenches or those carrying out relentless assault? Either faction has the potential for triumph; the defenders will prevail if they can fortify the trench with unwavering resolve, while the assailants will succeed if they can devise innovative means to breach the trench. Hence, bacterial biofilms pose a significant challenge and are formidable adversaries for medical professionals, often leading to the failure of antibiotic treatments in numerous hospital infections. Phage engineering has become the foundation for the targeted enhancement of various phage properties, facilitating the eradication of biofilms. Researchers across the globe have studied the impact of engineered phages and phage-derived enzymes on biofilms formed by difficult-to-treat bacteria. These novel biological agents have shown promising results in addressing biofilm-related challenges. The compilation of research findings highlights the impressive capabilities of engineered phages in combating antibiotic-resistant bacteria, superbugs, and challenging infections. Specifically, these engineered phages exhibit enhanced biofilm destruction, penetration, and prevention capabilities compared to their natural counterparts. Additionally, the engineered enzymes derived from phages demonstrate improved effectiveness in addressing bacterial biofilms. As a result, these novel solutions, which demonstrate high penetration, destruction, and inhibition of biofilms, can be regarded as a viable option for addressing infectious biofilms in the near future.

Remediation of pharmacophoric laboratory waste by using biodegradable carbon nanoparticles of bacterial biofilm origin

Research laboratories generate a broad range of hazardous pharmacophoric chemical contaminants, from drugs to dyes used during various experimental procedures. In the recent past, biological methods have demonstrated great potential in the remediation of such contaminants. However, the presence of pharmacophoric chemicals containing antibiotics, xenobiotics, and heavy metals suppresses the growth and survivability of used microbial agents, thus decreasing the overall efficiency of biological remediation processes. Bacterial biofilm is a natural arrangement to counter some of these inhibitions but its use in a systemic manner, portable devices, and pollutant remediation plants post serious challenges. This could be countered by synthesizing a biodegradable carbon nanoparticle from bacterial biofilm. In this study, extracellular polymeric substance-based carbon nanoparticles (Bio-EPS-CNPs) were synthesized from bacterial biofilm derived from Bacillus subtilis NCIB 3610, as a model bacterial system. The produced Bio-EPS-CNPs were investigated for physiochemical properties by dynamic light scattering, optical, Fourier-transformed infrared, and Raman spectroscopy techniques, whereas X-ray diffraction study, scanning electron microscopy, and transmission electron microscopy were used to investigate structural and morphological features. The Bio-EPS-CNPs exhibited negative surface charge with spherical morphology having a uniform size of sub-100 nm. The maximum remediation of some laboratory-produced pharmacophoric chemicals was achieved through a five-round scavenging process and confirmed by UV/Vis spectroscopic analysis with respect to the used pharmacophore. This bioinspired remediation of used pharmacophoric chemicals was achieved through the mechanism of surface adsorption via hydrogen bonding and electrostatic interactions, as revealed by different characterizations. Further experiments were performed to investigate the effects of pH, temperature, stirring, and the protocol of scavenging to establish Bio-EPS-CNP as a possible alternative to be used in research laboratories for efficient removal of pharmacophoric chemicals by incorporating it in a portable, filter-based device.

Structural characterization and potential anti-tumor activity of a polysaccharide from the halophyte Salicornia bigelovii Torr

Plant polysaccharides are highly potent bioactive molecules. Clarifying the structural composition and bioactivities of plant polysaccharides will provide insights into their structure-activity relationships. Therefore, herein, we identified a polysaccharide produced by Salicornia bigelovii Torr. and analyzed the structure and anti-tumor activity of its component, SabPS-1. SabPS-1 was 3.24 × 104 Da, primarily composed of arabinose (24.96 %), galactose (30.39 %), and galacturonic acid (23.20 %), rhamnose (6.21 %), xylose (4.99 %), glucuronic acid (3.12 %), mannuronic acid (1.75 %), mannose (1.69 %), glucose (1.54 %), fucose (1.12 %), and guluronic acid (1.03 %). The backbone of SabPS-1 was a → 4)-β-D-GalpA-(1→, →5)-α-L-Araf-(1→, and→4)-β-D-Galp-(1 → molecule with a branched chain of α-L-Araf-(1 → connected to sugar residues of →3,6)-β-D-Galp-(1 → in the O-3 position. SabPS-1 induced apoptosis and inhibited the growth of HepG-2 cells, with viability of 47.90 ± 4.14 (400 μg/mL), indicating anti-tumor activity. Apoptosis induced by SabPS-1 may be associated with the differential regulation of caspase 3, caspase 8, Bax, and Bcl-2. To the best of our knowledge, this is the first study to investigate the principal structures and anti-tumor biological activities of SabPS-1. Our findings demonstrated the excellent anti-tumor properties of SabPS-1, which will aid in the development of anti-tumor drugs utilizing Salicornia bigelovii Torr.

A review of experimental Assessment Processes of material resistance to marine and freshwater biofouling

Biofouling presents hazards to a variety of freshwater and marine underwater infrastructures and is one of the direct causes of species invasion. These negative impacts provide a unified goal for both industry practitioners and researchers: the development of novel antifouling materials to prevent the adhesion of biofouling. The prohibition of tributyltin (TBT) by the International Maritime Organization (IMO) in 2001 propelled the research and development of new antifouling materials. However, the evaluation process and framework for these materials remain incomplete and unsystematic. This mini-review starts with the classification and principles of new antifouling materials, discussing and summarizing the methods for assessing their biofouling resistance. The paper also compiles the relevant regulations and environmental requirements from different countries necessary for developing new antifouling materials with commercial potential. It concludes by highlighting the current challenges in antifouling material development and future outlooks. Systematic evaluation of newly developed antifouling materials can lead to the emergence of more genuinely applicable solutions, transitioning from merely laboratory products to materials that can be effectively used in real-world applications.

Coral larval settlement induction using tissue-associated and exuded coralline algae metabolites and the identification of putative chemical cues

Reef-building crustose coralline algae (CCA) are known to facilitate the settlement and metamorphosis of scleractinian coral larvae. In recent decades, CCA coverage has fallen globally and degrading environmental conditions continue to reduce coral survivorship, spurring new restoration interventions to rebuild coral reef health. In this study, naturally produced chemical compounds (metabolites) were collected from two pantropical CCA genera to isolate and classify those that induce coral settlement. In experiments using four ecologically important Caribbean coral species, we demonstrate the applicability of extracted, CCA-derived metabolites to improve larval settlement success in coral breeding and restoration efforts. Tissue-associated CCA metabolites induced settlement of one coral species, Orbicella faveolata, while metabolites exuded by CCA (exometabolites) induced settlement of three species: Acropora palmata, Colpophyllia natans and Orbicella faveolata. In a follow-up experiment, CCA exometabolites fractionated and preserved using two different extraction resins induced the same level of larval settlement as the unfractionated positive control exometabolites. The fractionated CCA exometabolite pools were characterized using liquid chromatography tandem mass spectrometry, yielding 145 distinct molecular subnetworks that were statistically defined as CCA-derived and could be classified into 10 broad chemical classes. Identifying these compounds can reveal their natural prevalence in coral reef habitats and facilitate the development of new applications to enhance larval settlement and the survival of coral juveniles.

Chemically mediated rheotaxis of endangered tri-spine horseshoe crab: potential dispersing mechanism to vegetated nursery habitats along the coast

Background

An enhanced understanding of larval ecology is fundamental to improve the management of locally depleted horseshoe crab populations in Asia. Recent studies in the northern Beibu Gulf, China demonstrated that nesting sites of Asian horseshoe crabs are typically close to their nursery beaches with high-density juveniles distributed around mangrove, seagrass and other structured habitats.

Methods

A laboratory Y-maze chamber was used to test whether the dispersal of early-stage juvenile tri-spine horseshoe crab Tachypleus tridentatus is facilitated by chemical cues to approach suitable nursery habitats. The juvenile orientation to either side of the chamber containing controlled seawater or another with various vegetation cues, as well as their movement time, the largest distance and displacement were recorded.

Results

The juveniles preferred to orient toward seagrass Halophila beccarii cues when the concentration reached 0.5 g l^-1, but ceased at 2 g l^-1. The results can be interpreted as a shelter-seeking process to get closer to the preferred settlement habitats. However, the juveniles exhibited avoidance behaviors in the presence of mangrove Avicennia marina and invasive saltmarsh cordgrass Spartina alterniflora at 2 g l^-1. The juveniles also spent less time moving in the presence of the A. marina cue, as well as reduced displacement in water containing the S. alterniflora cue at 1 and 2 g l^-1. These results may explain the absence of juvenile T. tridentatus within densely vegetated areas, which have generally higher organic matter and hydrogen sulfide.

Conclusion

Early-stage juvenile T. tridentatus are capable of detecting and responding to habitat chemical cues, which can help guide them to high-quality settlement habitats. Preserving and restoring seagrass beds in the intertidal areas should be prioritized when formulating habitat conservation and management initiatives for the declining horseshoe crab populations.

Structure and bioactivity of polysaccharide from a subseafloor strain of Schizophyllum commune 20R-7-F01

Fungal polysaccharide is a kind of biomacromolecule with multiple biological activities, which has a wide application prospect and may play an important role in organisms to cope with extreme environments. Herein, we reported an extracellular polysaccharide (EPS) produced by Schizophyllum commune 20R-7-F01 that was isolated from subseafloor sediments at ~2 km below the seafloor, obtained during expedition 337. The monosaccharide of EPS was glucose and its molecular weight was 608.8 kDa. Methylation and NMR analysis indicated that the backbone of the EPS was (1 → 3)-β-D-glucan with a side chain (1 → 6) β-D-glucan linking at every third residue. Bio-active assays revealed that the EPS had potent antioxidant activity and could promote RAW264.7 cells viability and phagocytosis. These results suggest that fungi derived from sediments below seafloor are important and new source of polysaccharides and may be involved in the adaptation of fungi to anoxic subseafloor extreme ecosystem.

Signalling molecules inducing metamorphosis in marine organisms

Covering: findings from early 1980s until early 2022Microbial-derived cues of marine biofilms induce settlement and metamorphosis of marine organisms, a process responsible for the emergence of diverse flora and fauna in marine habitats. Although this phenomenon is known for more than 80 years, the research field has only recently gained much momentum. Here, we summarize the currently existing biochemical and microbial knowledge about microbial signalling molecules, con-specific signals, and synthetic compounds that induce or prevent recruitment, settlement, and metamorphosis in invertebrate larvae. We discuss the possible modes of action and conclude with perspectives for future research directions in the field of marine chemical ecology.

Phages against Pathogenic Bacterial Biofilms and Biofilm-Based Infections: A Review

Bacterial biofilms formed by pathogens are known to be hundreds of times more resistant to antimicrobial agents than planktonic cells, making it extremely difficult to cure biofilm-based infections despite the use of antibiotics, which poses a serious threat to human health. Therefore, there is an urgent need to develop promising alternative antimicrobial therapies to reduce the burden of drug-resistant bacterial infections caused by biofilms. As natural enemies of bacteria, bacteriophages (phages) have the advantages of high specificity, safety and non-toxicity, and possess great potential in the defense and removal of pathogenic bacterial biofilms, which are considered to be alternatives to treat bacterial diseases. This work mainly reviews the composition, structure and formation process of bacterial biofilms, briefly discusses the interaction between phages and biofilms, and summarizes several strategies based on phages and their derivatives against biofilms and drug-resistant bacterial infections caused by biofilms, serving the purpose of developing novel, safe and effective treatment methods against biofilm-based infections and promoting the application of phages in maintaining human health.

Evidence for Host Selectivity and Specialization by Epizoic Chelonibia Barnacles Between Hawksbill and Green Sea Turtles

Epibionts are organisms that utilize the exterior of other organisms as a living substratum. Many affiliate opportunistically with hosts of different species, but others specialize on particular hosts as obligate associates. We investigated a case of apparent host specificity between two barnacles that are epizoites of sea turtles and illuminate some ecological considerations that may shape their host relationships. The barnacles Chelonibia testudinaria and Chelonibia caretta, though roughly similar in appearance, are separable by distinctions in morphology, genotype, and lifestyle. However, though each is known to colonize both green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles, C. testudinaria is >5 times more common on greens, while C. caretta is >300 times more common on hawksbills. Two competing explanations for this asymmetry in barnacle incidence are either that the species’ larvae are spatially segregated in mutually exclusive host-encounter zones or their distributions overlap and the larvae behaviorally select their hosts from a common pool. We indirectly tested the latter by documenting the occurrence of adults of both barnacle species in two locations (SE Florida and Nose Be, Madagascar) where both turtle species co-mingle. For green and hawksbill turtles in both locations (Florida: n = 32 and n = 275, respectively; Madagascar: n = 32 and n = 125, respectively), we found that C. testudinaria occurred on green turtles only (percent occurrence – FL: 38.1%; MD: 6.3%), whereas the barnacle C. caretta was exclusively found on hawksbill turtles (FL: 82.2%; MD: 27.5%). These results support the hypothesis that the larvae of these barnacles differentially select host species from a shared supply. Physio-biochemical differences in host shell material, conspecific chemical cues, external microbial biofilms, and other surface signals may be salient factors in larval selectivity. Alternatively, barnacle presence may vary by host micro-environment. Dissimilarities in scute structure and shell growth between hawksbill and green turtles may promote critical differences in attachment modes observed between these barnacles. In understanding the co-evolution of barnacles and hosts it is key to consider the ecologies of both hosts and epibionts in interpreting associations of chance, choice, and dependence. Further studies are necessary to investigate the population status and settlement spectrum of barnacles inhabiting sea turtles.

Complete genome sequence of Metabacillus sp. cB07, a bacterium inducing settlement and metamorphosis of coral larvae

The settlement and metamorphosis of coral larvae are the bottleneck of coral recruitment. They are critical for the extension of coral population, which is the basis of the restoration of degraded coral reef ecosystem. In this study, we described the genomic characteristics of Metabacillus sp. cB07, which can efficiently induce larvae settlement and metamorphosis of coral Pocillopora damicornis. This function is first reported in the genus Metabacillus. Strain cB07 was isolated from the coral Porites pukoensis, and comprised one circular chromosome of 4,148,576 bp (44.14 mol% G + C content), containing 4148 protein coding sequences. To explore the potential mechanism of coral larvae settlement and metamorphosis induced by Metabacillus sp. cB07, we predicted that numerous genes related to the bacterial inductive ability. The genome of Metabacillus sp. cB07 will be helpful for further insights into the mechanism of bacterial induction of settlement and metamorphosis of coral larvae.

Litter contamination at a salt marsh: An ecological niche for biofouling in South Brazil

The presence of solid litter and its consequences for coastal ecosystems is now being investigated around the world. Different types of material can be discarded in areas such as salt marshes, and various fouling organisms can associate with such items forming the Plastisphere. This study investigated the distribution of solid litter along zones (dry, middle, flooded) of a salt marsh environment in the Patos Lagoon Estuary (South Brazil) and the association of biofouling organisms with these items. Solid litter quantities were significantly higher in the dry zone when compared to the middle and flooded zones, showing an accumulation area where the water rarely reaches. Most items were made of plastic, as shown for many other coastal areas, and originated from food packaging, fishery and shipping activities and personal use. Although not statistically significant, there was a tendency of increased biofouling towards the flooded zone. Thirteen groups were found in association with solid litter items, mainly algae, amphipods, and gastropods. The preference for salt marsh zones, types of material and items' colour was highly variable among groups of organisms, which can be related to their varied physiological requirements. In summary, significant plastic contamination of salt marshes of the Patos Lagoon was associated with a heterogeneous distribution of fouling communities.

Household environmental microbiota influences early-life eczema development

Exposure to a diverse microbial environment during pregnancy and early postnatal period is important in determining predisposition towards allergy. However, the effect of environmental microbiota exposure during preconception, pregnancy and postnatal life on development of allergy in the child has not been investigated so far. In the S-PRESTO (Singapore PREconception Study of long Term maternal and child Outcomes) cohort, we collected house dust during all three critical window periods and analysed microbial composition using 16S rRNA gene sequencing. At 6 and 18 months, the child was assessed for eczema by clinicians. In the eczema group, household environmental microbiota was characterized by presence of human-associated bacteria Actinomyces, Anaerococcus, Finegoldia, Micrococcus, Prevotella and Propionibacterium at all time points, suggesting their possible contributions to regulating host immunity and increasing the susceptibility to eczema. In the home environment of the control group, putative protective effect of an environmental microbe Planomicrobium (Planococcaceae family) was observed to be significantly higher than that in the eczema group. Network correlation analysis demonstrated inverse relationships between beneficial Planomicrobium and human-associated bacteria (Actinomyces, Anaerococcus, Finegoldia, Micrococcus, Prevotella and Propionibacterium). Exposure to natural environmental microbiota may be beneficial to modulate shed human-associated microbiota in an indoor environment.

Bioprocess development for biosorption of cobalt ions and Congo red from aquatic mixture using Enteromorpha intestinalis biomass as sustainable biosorbent

Because of the increased amount of cobalt and Congo red dye effluents attributable to the industrial operations, the capacity of Enteromorpha intestinalis biomass as a sustainable source to achieve significant biosorption percent for both pollutants from dual solution was assessed. A fifty batch FCCCD experiments for biosorption of cobalt ions and Congo red dye were performed. The complete removal of Congo red dye was obtained at 36th run using an initial pH value of 10, 1.0 g/L of Enteromorpha intestinalis biomass, 100 and 200 mg/L of Congo red and cobalt for a 20-min incubation time. Meanwhile, a cobalt removal percent of 85.22 was obtained at 35th run using a neutral pH of 7.0, 3.0 g/L of algal biomass, 150 and 120 mg/L of Congo red, and cobalt for a 60-min incubation time. For further illustration and to interpret how the biosorption mechanism was performed, FTIR analysis was conducted to inspect the role of each active group in the biosorption process, it can be inferred that -OH, C-H, C=O, O-SO3- and C-O-C groups were mainly responsible for Co2+ adsorption of from aqueous dual solution. Also, scan electron microscope revealed the appearance of new shiny particles biosorbed on E. intestinalis surface after the biosorption process. EDS analysis proved the presence of Co2+ on the algal surface after the biosorption process.

Physicochemical Properties of Extracellular Polymeric Substances Produced by Three Bacterial Isolates From Biofouled Reverse Osmosis Membranes

This work describes the chemical composition of extracellular polymeric substances (EPS) produced by three bacteria (RO1, RO2, and RO3) isolated from a biofouled reverse osmosis (RO) membrane. We isolated pure cultures of three bacterial strains from a 7-year-old biofouled RO module that was used in a full-scale seawater treatment plant. All the bacterial strains showed similar growth rates, biofilm formation, and produced similar quantities of proteins and polysaccharides. The gel permeation chromatography showed that the EPS produced by all the strains has a high molecular weight; however, the EPS produced by strains RO1 and RO3 showed the highest molecular weight. Fourier Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance (¹H NMR), and Carbon NMR (¹³C NMR) were used for a detailed characterization of the EPS. These physicochemical analyses allowed us to identify features of EPS that are important for biofilm formation. FTIR analysis indicated the presence of α-1,4 glycosidic linkages (920 cm^-1) and amide II (1,550 cm^-1) in the EPS, the presence of which has been correlated with the fouling potential of bacteria. The presence of α-glycoside linkages was further confirmed by ¹³C NMR analysis. The ¹³C NMR analysis also showed that the EPS produced by these bacteria is chemically similar to foulants obtained from biofouled RO membranes in previous studies. Therefore, our results support the hypothesis that the majority of substances that cause fouling on RO membranes originate from bacteria. Investigation using ¹H NMR showed that the EPS contained a high abundance of hydrophobic compounds, and these compounds can lead to flux decline in the membrane processes. Genome sequencing of the isolates showed that they represent novel species of bacteria belonging to the genus Bacillus. Examination of genomes showed that these bacteria carry carbohydrates-active enzymes that play a role in the production of polysaccharides. Further genomic studies allowed us to identify proteins involved in the biosynthesis of EPS and flagella involved in biofilm formation. These analyses provide a glimpse into the physicochemical properties of EPS found on the RO membrane. This knowledge can be useful in the rational design of biofilm control treatments for the RO membrane.