Detection of anti-leptospiral antibodies using recombinant ErpY-like lipoprotein based latex agglutination test for serodiagnosis of animal leptospirosis
Precise and timely diagnosis is essential to prevent severe outcomes of leptospirosis in humans and animals. Existing diagnostic methods face challenges and limitations, underscoring the need for novel, field-applicable screening, and diagnostic tests/assays. This study evaluates the diagnostic utility of a recombinant ErpY-like lipoprotein (rErpY-LIC11966) in a latex agglutination test (LAT) for diagnosis of animal leptospirosis. The ErpY gene sequence from Leptospira interrogans serovar Pomona, excluding the signal peptide, was amplified, cloned into the pETite vector, and expressed in Escherichia coli. The expressed rErpY (∼16 kDa) was characterized by Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis and Western blot using Leptospira-specific standard sera. To assess the diagnostic potential of rErpY, Ni-NTA affinity-purified protein was used to sensitize latex-coated beads (0.8 µm colour beads), which were then employed in the LAT for standardization and optimization with standard positive and negative sera. For evaluation, the rErpY-LAT was tested on serum samples from 177 suspected animal cases and compared to the microscopic agglutination test. It showed a relative diagnostic sensitivity of 90.6%, a specificity of 89.1%, and an overall accuracy of 90%. This study proposes rErpY-LAT as a field testing/screening diagnostic tool for preliminary serodiagnosis of leptospirosis, highlighting the potential of recombinant protein-based assays to address current diagnostic challenges.
Xpert MTB/RIF Ultra as a diagnostic tool for pleural tuberculosis: a study at Indian tertiary care centre
Despite the advent of Xpert MTB/RIF, pleural tuberculosis (TB) diagnosis in pleural fluid is still difficult. Hence, we assessed the diagnostic efficacy of its advanced version, Xpert MTB/RIF Ultra, for pleural TB diagnosis using pleural fluid as a sample. Tuberculosis pleuritis (TBP) suspects (n = 261) were enrolled in the study, of which 29 were excluded. The remaining patients (n = 232) were categorized into definite TBP (n = 31), probable TBP (n = 28), and non-TB controls (n = 173) based on the composite reference standard consisting of smear, culture, histopathology, and Xpert MTB/RIF as well as follow-up/clinical response to anti-TB therapy. Among the TBP suspects, 59 were diagnosed as TBP patients. The sensitivity of Xpert MTB/RIF Ultra (52.5%) using pleural fluid for TBP diagnosis was higher than sensitivity obtained with smear (22.4%), culture (17.6%), and Xpert MTB/RIF (25%) alone, carried out using either pleural fluid or pleural biopsy or both the samples. In cases of probable TBP, where none of the laboratory tests were positive, Xpert MTB/RIF Ultra use led to an increased diagnostic percentage of definite TBP from 52.5% to 69.4%. Overall, Xpert MTB/RIF Ultra showed promising results for a definitive diagnosis of TBP in pleural fluid samples.
The application of ozone within the food industry, mode of action, current and future applications, and regulatory compliance
The food industry faces numerous challenges today, with the prevention and reduction of microbial contamination being a critical focus. While traditional chemical-based methods are effective and widely used, rising energy costs, the development of microbial tolerances, and growing awareness of the ecological impact of chemical biocides have renewed interest in novel biocides. Ozone, in both its gaseous and aqueous forms, is recognized as a potent disinfectant against bacteria, viruses, and fungi due to its high oxidation potential. Our review highlights several studies on the applications of ozone within the food industry, including its use for surface and aerosol disinfection and its capacity to reduce viable Listeria monocytogenes, a pertinent foodborne pathogen harbouring environmental and biocide stress tolerances and biofilm former. We also explore the use of ozone in food treatment and preservation, specifically on blueberries, apples, carrots, cabbage, and cherry tomatoes. While ozone is an effective disinfectant, it is important to consider material incompatibility, and the risks associated with prolonged human exposure to high concentrations. Nevertheless, for certain applications, ozone proves to be an efficacious and valuable alternative or complementary method for microbial control. Compliance with the biocide products regulation will require ozone device manufacturers to produce proven efficacy and safety data in line with British standards based on European standards (BS EN), and researchers to propose adaptations to account for ozone's unique properties.
Potential of Cellulomonas fimi for polysaccharide-fueled microbial fuel cells
To generate power from various biomass using microbial fuel cells (MFCs), microorganisms with high potential are essential. Therefore, this study examined the feasibility of using Cellulomonas fimi and Shewanella oneidensis as MFCs fueled by starch, cellulose, chitin, and chitosan. To our knowledge, this is the first report of power generation using C. fimi fueled by these polysaccharides other than cellulose, furthermore the first report of S. oneidensis fueled by chitosan. No differences were observed in the power generation capacities between C. fimi and S. oneidensis when chitin and chitosan were used. However, C. fimi demonstrated effective power generation from starch and cellulose, showing a maximum current density of 17.4 mA m-2 for starch and 38.8 mA m-2 for cellulose. Shewanella oneidensis could not utilize these fuels. Power generation using C. fimi fueled by starch and cellulose produced acetic acid, lactic acid, and formic acid. However, when chitin and chitosan were used, only acetic acid was produced. These results indicate that electron transfer from C. fimi to the anode may be inefficient. To improve power generation efficiency, it may be necessary to enhance electron transfer from the cells to the anode, e.g. by adding a mediator.
Mitigation of chemotherapy-induced experimental intestinal mucositis through postbiotic lactate
Postbiotic lactate modulates the immune system in inflammatory bowel diseases. However, its role in experimental intestinal mucositis (IM) has not been elucidated. This study aimed to evaluate the effects of lactate supplementation (1 and 2 × 10-1 mol/l) in a 5-fluorouracil (5-FU)-induced IM model. Male BALB/c mice (6-8 weeks old) were randomly divided into four groups: control (CTL), mucositis (MUC), mucositis with 1 × 10-1 mol/l lactate solution (MUC10), and mucositis with 2 × 10-1 mol/l lactate solution (MUC200). Lactate was administered via oral gavage for 10 days. Following the treatment period, the animals were subjected to an intraperitoneal injection of 300 mg/kg 5-FU to induce IM and were euthanized 72 h later for analysis. The MUC group presented intestinal damage with a poor histological score and decreased morphometric parameters as well as decreased mucus production and increased inflammatory infiltration and intestinal permeability compared to those of the CTL group (P < .05). However, the MUC200 group exhibited better results for the evaluated parameters than the MUC group (P < .05). Notably, the results in the MUC10 group were similar to those in the MUC group (P > .05). In conclusion, lactate supplementation attenuates mucositis-induced damage in a dose-dependent manner.
Depth-dependent bacterial colonization on model chitin particles in the open ocean
Sinking particles transport carbon from the surface to the deep ocean. Microbial colonization and remineralization is an important ecosystem service constraining the biogeochemistry by recycling and redistributing nutrients from the surface to the deep ocean. Fragmentation of particles by zooplankton and the resulting colonization by microorganisms before ingestion, known as 'microbial gardening', allows for trophic upgrading and increased microbial biomass for detritivorous zooplankton. Using model chitin particles incubated with seawater collected from surface, meso- and bathypelagic depths in the North-East Atlantic Ocean, we determined particle-attaching bacterial communities to identify general and depth-specific candidates of particle colonisation. Comparison of particle-attached communities at the amplicon sequence variant (ASV) level showed bacteria found on surface particles were also colonisers in the bathypelagic, in line with sinking particles promoting vertical connectivity. Bathypelagic particle-attached communities were most diverse. We propose some particle colonisers attach in the surface and sink out with the particle, whilst other colonisers are depth specific. This suggests that candidates for particle colonisation differ with depth, which may be important when considering the implications for delivery of ecosystem services including carbon cycling and the role they play for zooplankton grazers.
Isolation of lactiplantibacillus plantarum for treatment of Salmonella infection in mice
Salmonella infections, often acquired through contaminated food or water, pose significant health risks, particularly amid rising antibiotic resistance and the adverse effects of conventional treatments on gut microbiota. This study isolated the probiotic Lactiplantibacillus plantarum GOLDGUT-LP618 from healthy human fecal samples, demonstrating its potential against Salmonella enterica. L. plantarum LP618 produced high levels of short-chain fatty acids (SCFAs) and exhibited robust inhibition of Salmonella in vitro. The strain showed resilience in gastric and bile environments, effectively curbing Salmonella growth. Post-infection treatment with L. plantarum LP618 significantly alleviated diarrhea, improved body weight, and moderated inflammatory responses. Histological analysis indicated restoration of intestinal structure, suggesting protection against mucosal damage. These results highlight L. plantarum LP618 as a promising probiotic candidate, offering a safe and effective alternative to antibiotics for managing Salmonella infections and promoting recovery in affected individuals.
Molecular characterization of Staphylococcus aureus from nasal samples of healthy pet cats
The objective of this study was to characterize Staphylococcus aureus (S. aureus) isolates recovered from the nasal samples of healthy pet cats in Algiers province. A total of 138 nasal swabs were collected. Antimicrobial susceptibility was conducted using the disk-diffusion method and the VITEK-2 susceptibility system. Whole genome sequencing (WGS) was performed to identify multiple-locus sequence typing (MLST), antimicrobial and virulence genes. S. aureus isolates were detected in 23 cats. Among these, 11 were methicillin-resistant S. aureus (MRSA) (one isolate/sample). Three sequence types (ST6, ST5, and ST1) were identified in MRSA, with the predominance of ST6 (n = 7). Seven distinct STs (ST398, ST97, ST15, ST7, ST291, ST5043 and a new ST, (ST9219)) were detected in methicillin-sensitive S. aureus (MSSA). All MRSA isolates harbored the mecA gene and SCCmec-type-IVa. MRSA exhibited resistance to tetracycline (n = 3/tet(L) and tet(M); n = 1/tet(K)), kanamycin-tobramycin (n = 3/ant(4')-Ia), amikacin-kanamycin (n = 1/aph(3')-IIIa), and erythromycin-clindamycin (n = 1/erm(C)). Seven S. aureus isolates were multidrug-resistant. All the isolates were negative for lukS/lukF-PV and tst-1 genes, while 20 isolates were IEC-positive. This study revealed a diversity of genetic lineages in S. aureus strains isolated from nasal samples of pet cats, including multidrug-resistant and toxigenic strains. The presence of IEC-positive S. aureus suggests possible human-animal transmission.
Biochemical characterization of HcrF from Limosilactobacillus fermentum, a NADH-dependent 2-ene reductase with activity on hydroxycinnamic acids
In fermented plant foods, phenolic compounds are metabolized by 2-ene reductases, which reduce double bonds adjacent to an aromatic rings in phytochemicals including hydroxycinnamic acids, isoflavones, and flavones. Only few 2-ene reductases of lactic acid bacteria were characterized, including the hydrocinnamic reductases HcrB and Par1, and the daidzein reductase of Lactococcus lactis. This study aimed to characterize HcrF, a homologue of HcrB, in Limosilactobacillus fermentum. HcrF was purified after cloning in Escherichia coli and purification by affinity chromatography. HcrF was optimally active at 30 - 40°C and pH 7.0 and required both FMN and NADH as co-factors. Ferulic, caffeic, p-coumaric and sinapic acids but not trans-cinnamic acids were reduced to dihydro derivatives. The maximum reaction velocity Vmax of HcrF was highest for ferulic acid. On a phylogenetic tree of 2-ene reductases, HcrF clustered most closely with the hydroxycinnamic acid reductase HcrB of Lactiplantibacillus plantarum. The hydroxycinnamic acid reductase Par1 of Furfurilactobacillus milii and flavone or isoflavone reductases were only distantly related to HcrF. In summary, current knowledge does not allow to predict the substrate specificity of 2-ene reductases on the basis of the protein sequence; this study adds HcrF to the short list of enzymes with known substrate specificity.
Cultivar-dependent differences in plant bud microbiome and functional gene pathways in woody plants commonly used in urban green space
Plant richness and microbiota have been associated with plant health; hardly any studies have investigated how plant taxa differs in microbiota in the context of human health. We investigated the microbial differences in buds of 83 woody plant taxa used in urban green spaces in hemiboreal climate, using 16S rRNA and whole metagenome shotgun sequencing. Bud microbial community was the richest in Cotoneaster Nanshan and C. integerrimus, and Malus domestica cultivars 'Sandra' and 'Lobo' and poorest in Ribes glandulosum. Metagenomic shotgun sequencing of two M. domestica and four Ribes varieties confirmed differences in taxa in bud microbiota and indicated higher siderophore synthesis in Malus. Microbial richness, including bacteria, archaea and viruses, and functional richness of gene pathways was higher in Malus compared to Ribes. The ten most abundant amplicon sequence units, often referred as species, belonged to the phylum Proteobacteria. The differences between plant taxa were evident in classes Alpha- and Gammaproteobacteria, known for potential human health-benefits. Since environmental microbiota contributes to human microbiota and immunoregulation, horticultural cultivars hosting rich microbiota may have human health benefits. Further studies are needed to confirm the effectiveness of microbially-oriented plant selection in optimizing human microbiota and planetary health.
Impact of probiotic Bacillus sp. dietary supplementation on pancreatic and intestinal activities in seabream Sparus aurata
The main objective of this study was to investigate the effects of commercial probiotic Bacillus sp. supplementation on seabream Sparus aurata larviculture under culture conditions. In this context, Bacillus was supplemented via rotifer feeding and water and its effects on pancreatic and intestinal enzyme activities as well as aquaculture parameters were evaluated during early life development. In the experimental group, as probiotic three Bacillus sp. spores were introduced via rotifer and larval culture tanks, while the larvae in control group did not feed any probiotic supplementation. At the end of the experiment on 40 days after hatching, the probiotic-supplemented group exhibited better growth performance and there were statistically differences in between groups of probiotic-treated and control regarding growth parameters (P < 0.01), despite insignificant survival rate (P > 0.05). In terms of enzymatic expressions, S. aurata larvae receiving probiotic supplementation through rotifers demonstrated noteworthy (P < 0.05) enhancements in specific activities of pancreatic and intestinal enzymes, except for amylase (P > 0.05), when compared to the control group. It is concluded that the administration of Bacillus sp. as probiotic bacteria through rotifer supplementation and water intake demonstrates significant positive impacts on both growth parameters and specific activities of main pancreatic and intestinal enzymes of seabream larvae.
Bacterial composition and cultural dynamics of microgreens-associated microbiota during selective enrichment for Listeria monocytogenes
Widely-regarded as a so-called "superfood", microgreens have become an increasingly significant food crop from both nutritional and agricultural standpoints. However, similar to other produce commodities that are also cultivated using modernized indoor-farming methods, there have been mounting concerns over the potential risks of consuming microgreens contaminated by Listeria monocytogenes. To gain insights into the microbial properties of microgreens, this study characterized the bacterial composition of fresh microgreen retail products using amplicon sequencing of 16S rRNA genes. Dominated by Gammaproteobacteria, a total of 36 shared genera were identified as putative constituents of the microgreen core microbiome. By monitoring the dynamics of microgreen-borne bacteria undergoing a Listeria-selective cultural enrichment procedure, it was revealed that, regardless of the presence or absence of L. monocytogenes, off-target bacteria of the Klebsiella and Enterococcus genera were significantly enriched from microgreens by the primary enrichment step, with the secondary enrichment step continuing to promote the expansion of Enterococcus population. While Listeria was generally neither the most-enriched nor the dominant taxon in cultures sampled at different enrichment stages, significant enrichment of Lysinibacillus and Bacillus bacteria were detected in microgreens contaminated with L. monocytogenes, suggesting they could be co-enriched in competition with Listeria.
Impact of High Hydrostatic Pressure and UV-C Radiation on Total Aerobic Bacteria in Minas Frescal Cheese
Minas Frescal cheese (MFC) is a perishable product with high water activity and neutral pH, conditions that favor the development of microorganisms. Total aerobic bacteria (TAB) can deteriorate the cheese, negatively affecting its sensory characteristics. By controlling TAB, the shelf life of the product is extended and its quality is maintained, contributing to meeting consumer expectations. This study aimed to evaluate the individual and combined effect of technological treatments of high hydrostatic pressure (HHP) and ultraviolet C radiation (UV-C) on the TAB count present in the natural microbiota of MFC, as an alternative to control the microbiological quality of this product. After production, MFC were subjected to treatments with different levels of HHP (100 to 400 MPa/10 min) and UV-C (0.097 to 0.392 J/cm2.s-1). The combinations of HHP and UV-C doses were determined by a central composite rotational design (CCRD). The model efficiently described the individual and combined effect of HHP and UV-C on TAB, demonstrating that gradually increasing HHP levels reduces TAB counts in MFC, regardless of the UV-C dose applied. This study contributes significantly to the literature by providing new insights into how these technologies can be used to improve the microbiological quality of fresh cheeses.
Integrated neural network and PSO hybrid approach for production of citrulline using immobilized permeabilized Pseudomonas furukawaii
In the present study, nutraceutical citrulline was produced using immobilization of permeabilized whole cells of Pseudomonas furukawaii, an efficient producer of ADI. Since ADI is intracellularly localized, various additives such as SDS, Triton X-100, and EDTA were used to permeabilize the cell to improve substrate accessibility and ADI activity. The maximum ADI activity was observed with 0.25 mg mL-1 biomass concentration treated with 0.5 mmol L-1 EDTA for 15 min using OFAT approach. Optimization of permeabilization conditions of P. furukawaii cells using novel neural networks and particle swarm optimization (PSO-NN) led to maximum ADI activity with 0.10 mmol L-1 EDTA and 0.30 mg mL-1 biomass. Further, the morphological characterization of immobilized cells was assessed by FESEM and FTIR. An optimal citrulline production of 1.19 mmol L-1 was achieved at 2.5% sodium alginate with 20 mmol L-1 arginine at 38°C, and 180 min of incubation. The immobilized cells retained 90.3% productivity after seven reuse cycles. Thus, the formulated immobilized whole-cell biocatalyst, with higher stability offers cost-effective methods of citrulline production.
Marine Pseudomonas: diving into the waves of blue biotechnology
From marine to terrestrial environments, Pseudomonas spp. exhibit a remarkable ability not only to adapt but also thrive even amidst adverse conditions. This fact turns Pseudomonas spp. into one of the most prominent candidates for novel biotechnological solutions. Even though terrestrial isolates have been extensively studied, there is still an almost untapped source to be explored in marine Pseudomonas. Harnessing such strains offers an opportunity to discover novel bioactive compounds that could address current global challenges in healthcare and sustainable development. Therefore, this minireview aimed to provide an overview of the main recent discoveries regarding antimicrobials, antifouling, enzymes, pigments, and bioremediation strategies derived from marine isolates of Pseudomonas spp. Future research perspectives will also be discussed to foster forthcoming endeavors to explore the marine counterparts of such a prolific bacterial genus.
Microbial Decomposer for Crop Residue Management in Rice-Wheat Cropping System
Crop residue management is vital in the Rice-Wheat cropping system, influencing soil health and crop productivity. This study examined the effects of organic and inorganic fertilizers and microbial decomposers on rice growth and yield. We evaluated seven treatments: 100% recommended dose fertilizer (RDF); 50% residue + 50% RDF; 50% residue + 50% RDF + Pusa decomposer; 50% residue + 50% Green Manuring (GM)/Green Leaf Manuring (GLM); 50% residue + 50% GM/GLM + Pusa decomposer; Residue @ 2.5 tons per acre + Pusa decomposer; Residue @ 2.5 tons per acre + no Pusa decomposer; and absolute control. Results indicate that integrating organic and inorganic fertilizers with microbial decomposers positively affects rice growth and yield parameters. While adding microbial decomposer to RDF did not consistently enhance rice yield, it improved soil enzymatic properties. This suggests that the effectiveness of microbial decomposers may vary based on specific soil and crop conditions. Therefore, microbial decomposers present a promising approach to boost soil health and fertility. Further research is needed to optimize conditions for their use and systematically assess their impact on crop yields.
Optimization and scaling up of extracellular polysaccharide production by submerged culture of Ganoderma lucidum on starch-containing medium using response surface methodology and laboratory bioreactors of various designs
Basidiomycetes, known for their production of bioactive compounds, traditionally use simple sugars for fermentation. However, their ability to degrade complex plant polysaccharides through enzyme secretion presents potential for the use of renewable raw materials. This study focused on the optimization of exopolysaccharide (EPS) production and efficient substrate consumption by Ganoderma lucidum using response surface methodology (RSM). Using an optimized medium containing 15 g⋅L-1 wheat starch, 0.375 g⋅L-1 NH4Cl, and 0.75 g⋅L-1 CaCl2 (C/N ratio of 40), a significant increase in EPS concentration from 121.1±10.2 mg⋅L-1 to 229.0±20.3 mg⋅L-1 and starch degradation degree (SDD) from 9.1% to 57.6% was achieved after 9 d of submerged cultivation. Scale-up experiments were conducted in both column and stirred tank bioreactors, employing submerged and immobilized cultivation modes. Submerged cultivation in the column bioreactor yielded the highest process desirability of 0.56, achieving EPS concentration of 192.5±5.4 mg⋅L-1 and 60.2% starch degradation degree within 7 d. These results highlight the potential of the used column bioreactor for efficient and rapid EPS production. Notably, bioreactor experiments revealed local maxima in EPS content at specific time points, suggesting that cell wall degradation, potentially induced by shear stress, may contribute to the release of polysaccharides into the culture broth.
A One Health exploration of antimicrobial resistance in Escherichia coli originated from urban and rural lakes ecosystem
Antimicrobial resistance (AMR) has become one of the most serious threats to One Health. Aquatic environments are an ideal non-clinical AMR reservoir and can act as a key battlefront for tackling the AMR. However, AMR data using the One Health approach remain scarce in aquatic environments worldwide. Here, we extensively assessed AMR in Escherichia coli isolated from urban and rural lake ecosystems using the One Health perspective. A total of 162 E. coli isolates obtained from lakes were tested against 25 antimicrobials using an in-vitro antimicrobial susceptibility testing method. A low (2%) to moderate (45%) drug resistance rate was found for all antimicrobials used in human/veterinary medicine or animal/plant agriculture. However, <80% E. coli isolates exhibited multidrug resistance (MDR) phenotype to highly important (amikacin, gentamicin, trimethoprim) or critically important (amoxicillin, ampicillin, colistin) drugs of both human and veterinary medicine. Of concern, >50% of E. coli isolates exhibited MDR to drugs used as last-resorts (chloramphenicol, colistin) or as frontline (nitrofurantoin, sulfamethoxazole, ampicillin, gentamicin) against E. coli infections. In conclusion, the presence of MDR E. coli strains in urban or rural lake ecosystems highlights their possible role as AMR reservoirs with potential One Health risks.
Phenotypic and molecular characterization of vancomycin resistant enterococci from wild birds: first detection of a plasmid-borne vanC1 in Enterococcus faecalis
Vancomycin-resistant enterococci (VRE) are a public health concern as they lead to therapeutic impasses and play a pivotal role in the dissemination of vancomycin resistance genes. As recent evidence suggests that wildlife can play a role in the dissemination of bacterial resistomes, this study explored the potential role of Algerian wild birds as a reservoir of VRE. A total of 222 cloacal and fecal samples were collected from various wild bird species and screened for VRE using a selective medium. Of the 47 isolated strains, 22 were identified as Enterococcus casseliflavus with the vanC2/C3 gene, 24 as Enterococcus gallinarum (19 carrying vanC1 and five carrying vanC2/C3), and one strain as Enterococcus faecalis with the vanC1 gene. Twenty-four (24) strains were multidrug-resistant with 61.7% resistant to rifampicin, while no resistance to teicoplanin, linezolid, and gentamicin was found. Additionally, 53.20% of the strains exhibited at least one virulence factor. To our knowledge, this study represents the first documentation of the vanC1 gene in E. faecalis isolated from wild birds. Furthermore, this gene was found to be carried by a conjugative plasmid, highlighting its ability to spread among bacterial populations and lead to the emergence of novel resistance phenotypes.
Editor's note on 'Preventing contamination of PCR-based multiplex assays including the use of a dedicated biosafety cabinet'
Retraction of: The gene coding for nigrescin produced by Prevotella nigrescens ATCC 25261