Non-pathogenic Strains Research Articles

Antimicrobial resistance profiles of non-pathogenic Escherichia coli in pig farms in Colombia

Background: Antibiotic resistance is a global public health problem. So far, there are limited studies focused on Escherichia coli isolated from pig herds in Colombia. Objective: The objective of this work was to evaluate the resistance to antibiotics of non-pathogenic strains of E. coli isolated from pig farms. Methods: The hemolytic capacity and the presence of thermolabile (LT) and thermostable toxins (STa and STb) were evaluated. Finally, the resistance capacity of the strains to 11 commonly used antibiotics was evaluated in γ - hemolytic strains. Results: A total of 6 E. coli were isolated. The strains presented a high resistance capacity to antibiotics. The highest prevalence of resistance was against Amikacin (20%), Ceftiofur (20%), Fosfomycin (20%), Ciprofloxacin (40%), Gentamicin (40%), Florfenicol (80%), Enrofloxacin Baytril (80%), Norfloxacin (80%), Apramycin (100%), Ampicillin (100%) and Doxycycline (100%). Conclusions: Therefore, commensal strains of E. coli from piglets represent a high epidemiological risk to conserving and disseminating resistance genes in the pig production chain. In addition, these strains have a potential risk of presence in the food chain.

Synthesis, Structure, Biological Activity, and Luminescence Properties of a "Butterfly"-Type Silver Cluster with 3-Benzyl-4-phenyl-1,2,4-triazol-5-thiol.

A new silver(I) cluster [Ag8L4(Py)(Pype)]·4Py·11H2O (I) with 3-benzyl-4-phenyl-1,2,4-triazol-5-thiol (L) was synthesized via the direct reaction of AgNO3 and L in MeOH, followed by recrystallization from a pyridine-piperidine mixture. The compound I was isolated in a monocrystal form and its crystal structure was determined via single crystal X-ray diffraction. The complex forms a "butterfly" cluster with triazol-5-thioles. The purity of the silver complex and its stability in the solution was confirmed via NMR analysis. Excitation and emission of the free ligand and its silver complex were studied at room temperature for solid samples. The in vitro biological activity of the free ligand and its complex was studied in relation to the non-pathogenic Mycolicibacterium smegmatis strain. Complexation of the free ligand with silver increases the biological activity of the former by almost twenty times. For the newly obtained silver cluster, a bactericidal effect was established.

Intentional use of harmful biological agents in work processes in Poland based on the National Register of Biological Agents

The work presents the intentional use of harmful biological agents based on National Register of Biological Agents (Krajowego Rejestru Czynników Biologicznych - KRCB) collected by June 2023. The KRCB is a central database gathering notifications of the intentional use of biological agents in risk groups 2-4 in the workplace in accordance with the regulation of the Minister of Health of December 11, 2020 amending the regulation regarding biological agents. with the regulation of the Minister of Health of December 11, 2020 amending the regulation regarding biological agents. Results: Notifications were sent by 712 enterprises for: diagnostic - 62%, research - 31% and industrial purposes - 7%. Notifications were most often sent by hospital and non-hospital clinical and diagnostic laboratories (33% each group) and higher education and research units - 16%. In total, 7352 workers (88% women, 12% men) were exposed to biological agents intentionally used at work. Biological agents from 2 and 3 group risk were used by 98% and 16% enterprises, respectively. The most frequently were used bacteria Escherichia coli (with the exception of non-pathogenic strains) - 5972 (81%) exposed workers, Staphylococcus aureus - respectively 5760 (78%) and Pseudomonas aeruginosa - 5155 (70%). Among the total workers, nearly 25% were exposed to at least 1 biological agent carcinogenic to humans, including viruses (hepatitis B virus [HBV] - 1800 workers, 24%; hepatitis C virus [HCV] - respectively, 1767, 24%; human immunodeficiency virus-1 [HIV-1] - 1557, 21%; human gammaherpesvirus type 4 (Epstein-Barr virus) - 199, 3%; Papillomaviridae - 52, <1%; human gammaherpesvirus type 8 [HHV-8] - 16, <1%; human T-lymphotropic virus type 1 [HTLV- 1] - 38, <1%; bacteria Helicobacter pylori - 299, 4%; parasites Schistosoma haematobium - 9, <1%). Intentionally used biological agents most often pose a threat to workers of hospital and non-hospital clinical and diagnostic laboratories, but a higher health risk concerns workers of and higher education and research units. Med Pr Work Health Saf. 2023;74(6):501-11.

Nitric Oxide As a Signaling Molecule for Biofilm Formation and Dispersal in Mediated Electron Transfer Microbial Electrochemical Systems

With applications in bioremediation, biosensing, and bioenergy, microbial electrochemical systems are a rapidly growing, multidisciplinary field within biological, chemical, and materials science. Since these systems use living microorganisms as biocatalysts, it is important to understand how microbial physiology, namely biofilm formation, affects these electrochemical systems. Specifically, the literature lacks research that assesses the effects of biofilm on metabolic current output in mediated electron transfer systems. In this study, Rhodobacter capsulatus and Pseudomonas putida GPo1 were used as model, nonpathogenic strains that facilitate electron transfer via diffusible redox mediators. Nitric oxide has gained attention in biomedicine as a gaseous signaling molecule, which at sublethal concentrations may either augment or inhibit biofilm formation depending on the bacterial species. In R. capsulatus, nitric oxide treatment was associated with increased current yield and improved biofilm formation. However, in P. putida GPo1, nitric oxide treatment corresponded to significantly reduced current output, as well as biofilm dispersal. In addition to highlighting the use of electrochemical tools to assess the effects of nitric oxide in biofilm formation, these findings demonstrate that biofilm-based mediated electron transfer systems benefit from the increased electrochemical output and enhanced cell adhesion, which is promising for more robust applications compared to their planktonic counterparts. Figure 1

Bacteriophage and non-pathogenic Vibrio to control diseases in shrimp aquaculture

The study aimed to address the recurring outbreaks of microbial diseases in shrimp aquaculture in Bangladesh the study focused on the utilization of bacteriophages and non-pathogenic Vibrio. The bacteriophages were isolated from sewage water sample collected from shrimp farm, hatchery, and the JUST campus. The bacteriophages were tested for their ability to infect different Vibrio strains in order to assess their bacteriolytic activity. Non-pathogenic Vibrio strains were obtained from suspected diseased isolates collected from the south-western region of Bangladesh through PCR amplification. In laboratory tests, the bacteriophages successfully infected 91 % of the tested Vibrio strains (19 out of 21 strains). In the experimental unit, shrimp treated with phage prophylaxis and phage treatment demonstrated notable protection against AHPND and was able to survive a deadly bacterial challenge. A total of 35 suspected diseased isolates were tested, and PCR amplification revealed 6 non-pathogenic Vibrio strains. In field trials, cultured bacteriophages were applied at a concentration of 1.5×106 PFU/ml, while non-pathogenic Vibrio was applied at 5×105 CFU/ml. The trials showed increased protection against infections and no severe deaths during the adaptive research phase. The cultured shrimp were analyzed morphologically and showed a muscle gut ratio greater than 4:1. No abnormal deformities were observed in their appendages or overall body, suggesting their overall health and well-being. The bacteriological tests conducted on the shrimp samples (application of bacteriophages and non-pathogenic Vibrio) revealed that 18 % of them were infected with bacteria, primarily Vibrio cholerae, Vibrio parahaemolyticus, and other bacterial species. Despite this, the infections did not lead to a disease outbreak; PCR amplification showed negative results for AHPND, White Spot Syndrome Virus (WSSV), and Enterocytozoon hepatopenaei (EHP). The results highlight the potential of using bacteriophages and non-pathogenic Vibrio as a sustainable solution for preventing and controlling microbial diseases in shrimp aquaculture. Furthermore, this study will contribute valuable insights into the development of alternative strategies to combat antibiotic resistance and promote the growth of the shrimp industry in Bangladesh.

Rationally Designed Novel Phenyloxazoline Synthase Inhibitors: Chemical Synthesis and Biological Evaluation to Accelerate the Discovery of New Antimycobacterial Antibiotics.

The uncontrolled spread of drug-resistant tuberculosis (DR-TB) clinical cases necessitates the urgent discovery of newer chemotypes with novel mechanisms of action. Here, we report the chemical synthesis of rationally designed novel transition-state analogues (TSAs) by targeting the cyclization (Cy) domain of phenyloxazoline synthase (MbtB), a key enzyme of the conditionally essential siderophore biosynthesis pathway. Following bio-assay-guided evaluation of TSA analogues preferentially in iron-deprived and iron-rich media to understand target preferentiality against a panel of pathogenic and non-pathogenic mycobacteria strains, we identified a hit, i.e., TSA-5. Molecular docking, dynamics, and MMPBSA calculations enabled us to comprehend TSA-5's stable binding at the active site pocket of MbtB_Cy and the results imply that the MbtB_Cy binding pocket has a strong affinity for electron-withdrawing functional groups and contributes to stable polar interactions between enzyme and ligand. Furthermore, enhanced intracellular killing efficacy (8 μg/mL) of TSA-5 against Mycobacterium aurum in infected macrophages is noted in comparison to moderate in vitro antimycobacterial efficacy (64 μg/mL) against M. aurum. TSA-5 also demonstrates whole-cell efflux pump inhibitory activity against Mycobacterium smegmatis. Identification of TSA-5 by focusing on the modular MbtB_Cy domain paves the way for accelerating novel anti-TB antibiotic discoveries.

Rapid turnover and short-term blooms of Escherichia coli in the human gut.

Escherichia coli (E. coli) is a common microorganism that is widely present in the environment and closely related to human health. The extent of E. coli presence in the human gut has been a subject of ongoing debate. Through whole-genome shotgun metagenomic sequencing, our study revealed that E. coli exists in the human body at a low abundance (average abundance 1.21%), with occasional short-term bursts leading to temporary increases in abundance, with the highest recorded at 50.91%. Further investigations into the factors contributing to these short-term blooms of E. coli showed significant variations in strain types and genomes within fecal samples collected from the same individuals at different time points. Evolutionary tree analysis indicated that samples from different individuals crossed, suggesting a change in the dominant E. coli strains within the human gut. Therefore, it can be inferred that E. coli in the human body are more likely to be transient bacteria rather than permanent residents in the gut. The rapid rate of turnover among months (87.5% within a month) and short-term blooms of E. coli in the human body can establish "latent infections" of nonpathogenic strains in healthy individuals while also posing a potential risk of introducing pathogenic strains, thereby impacting human health. In summary, our study revealed the variation in E. coli abundance and strains within the human gut, influenced by geographic area and temporal factors. These findings contribute to a better understanding of the relationship between E. coli, the gut microbiota, and human health. IMPORTANCE Escherichia coli (E. coli) is a microorganism closely linked to human health, and its presence in the human gut has been a topic of debate. Our study, using whole-genome shotgun metagenomic sequencing, revealed that E. coli exists at a low abundance in the human body, with occasional short-term bursts leading to temporary increases. Strain and genome variations were observed within fecal samples from the same individuals at different time points, suggesting transient rather than permanent residence of E. coli in the gut. The rapid turnover rate and short-term blooms of E. coli can establish latent infections while also posing a risk of introducing pathogenic strains. These findings enhance our understanding of the relationship between E. coli, the gut microbiota, and human health.

Potentially Pathogenic Bacteria in Nesting Olive Ridley Turtles in Northwestern Mexico.

Olive ridleys (Lepidochelys olivacea) are the most common sea turtle found in the Gulf of California. Unfortunately, the bacterial flora of nesting olive ridley turtles is still unknown. We conducted a study to identify, characterize, serotype, and determine the antibiotic resistance of potentially pathogenic bacteria isolated from olive ridley turtles nesting in northwestern Mexico. Bacteria were isolated and identified from the oral cavity and cloaca of 47 postnesting turtles. Escherichia coli and Vibrio parahaemolyticus were characterized, and antibiotic resistance testing was performed. One hundred bacteria belonging to 21 species were isolated, 53 from the oral cavity and 47 from the cloaca, the most prevalent being Pseudomonas aeruginosa, followed by Aeromonas hydrophila, Vibrio alginolyticus, Vibrio parahaemolyticus, Klebsiella pneumoniae, and E. coli, among others. Moreover, two to three different bacterial species were found co-colonizing both anatomical sites in some turtles. E. coli phylogroups B1, A, F, and unknown were identified as diarrheagenic E. coli (enteroaggregative and enteropathogenic E. coli). O1, O4, K8, K12, OUT, and KUT of V. parahaemolyticus serogroups were identified, also comprising pathogenic and nonpathogenic strains. Finally, 100% of the bacterial species tested were antibiotic resistant, and both MDR and XDR strains were found. In conclusion, olive ridley turtles are colonized by a diversity of bacterial species with a high rate of antibiotic resistance, some with pathogenic potential to turtles, representing a health risk factor for the species.

Mixed-ligand complex [Cu4(bpy)4(PO4)2(CO3)(H2O)2]: synthesis, crystal structure and biological properties

The interaction in the system {Сu(OAc)2·H2O–phytic acid–2,2`-bipyridine (bpy)} in an aqueous-methanol solution led to the formation of a molecular mixed-ligand tetranuclear complex [(Cu4(bpy)4(PO4)2(CO3 )(H2O)2]13H2O (I), the structure of which was established based on the results of an X-ray diffraction experiment (CCDC 2262998). According to X-ray diffraction data, the molecule contains four nonequivalent Cu2+ cations, which coordinate two phosphate anions (PO43-, remaining as a result transformation of the phytate cycle), four neutral bpy, two water molecules and one carbonate anion fragment (CO32-). The presence of a large number of solvate water molecules in the outer coordination sphere created a hydrogen-bonded framework involved in the stabilization of the crystal packing. Study of antimycobacterial activity of I in against the non-pathogenic strain Mycolicibacterium smegmatis showed its high bioeffectiveness.

The critical role of interleukin-6 in protection against neurotropic flavivirus infection.

West Nile virus (WNV) and Japanese encephalitis virus (JEV) are emerging mosquito-borne flaviviruses causing encephalitis globally. No specific drug or therapy exists to treat flavivirus-induced neurological diseases. The lack of specific therapeutics underscores an urgent need to determine the function of important host factors involved in flavivirus replication and disease progression. Interleukin-6 (IL-6) upregulation has been observed during viral infections in both mice and humans, implying that it may influence the disease outcome significantly. Herein, we investigated the function of IL-6 in the pathogenesis of neurotropic flavivirus infections. First, we examined the role of IL-6 in flavivirus-infected human neuroblastoma cells, SK-N-SH, and found that IL-6 neutralization increased the WNV or JEV replication and inhibited the expression of key cytokines. We further evaluated the role of IL-6 by infecting primary mouse cells derived from IL-6 knockout (IL-6-/-) mice and wild-type (WT) mice with WNV or JEV. The results exhibited increased virus yields in the cells lacking the IL-6 gene. Next, our in vivo approach revealed that IL-6-/- mice had significantly higher morbidity and mortality after subcutaneous infection with the pathogenic WNV NY99 or JEV Nakayama strain compared to WT mice. The non-pathogenic WNV Eg101 strain did not cause mortality in WT mice but resulted in 60% mortality in IL-6-/- mice, indicating that IL-6 is required for the survival of mice after the peripheral inoculation of WNV or JEV. We also observed significantly higher viremia and brain viral load in IL-6-/- mice than in WT mice. Subsequently, we explored innate immune responses in WT and IL-6-/- mice after WNV NY99 infection. Our data demonstrated that the IL-6-/- mice had reduced levels of key cytokines in the serum during early infection but elevated levels of proinflammatory cytokines in the brain later, along with suppressed anti-inflammatory cytokines. In addition, mRNA expression of IFN-α and IFN-β was significantly lower in the infected IL-6-/- mice. In conclusion, these data suggest that the lack of IL-6 exacerbates WNV or JEV infection in vitro and in vivo by causing an increase in virus replication and dysregulating host immune response.

Comparative Genomic Analysis of Shrimp-Pathogenic Vibrio parahaemolyticus LC and Intraspecific Strains with Emphasis on Virulent Factors of Mobile Genetic Elements.

Vibrio parahaemolyticus exhibits severe pathogenicity in humans and animals worldwide. In this study, genome sequencing and comparative analyses were conducted for in-depth characterization of the virulence factor (VF) repertoire of V. parahaemolyticus strain LC, which presented significant virulence to shrimp Litopenaeus vannamei. Strain LC, harboring two circular chromosomes and three linear plasmids, demonstrated ≥98.14% average nucleotide identities with 31 publicly available V. parahaemolyticus genomes, including 13, 11, and 7 shrimp-, human-, and non-pathogenic strains, respectively. Phylogeny analysis based on dispensable genes of pan-genome clustered 11 out of 14 shrimp-pathogenic strains and 7 out of 11 clinical strains into two distinct clades, indicating the close association between host-specific pathogenicity and accessory genes. The VFDB database revealed that 150 VFs of LC were mainly associated with the secretion system, adherence, antiphagocytosis, chemotaxis, motility, and iron uptake, whereas no homologs of the typical pathogenic genes pirA, pirB, tdh, and trh were detected. Four genes, mshB, wbfT, wbfU, and wbtI, were identified in both types of pathogenic strains but were absent in non-pathogens. Notably, a unique cluster similar to Yen-Tc, which encodes an insecticidal toxin complex, and diverse toxin-antitoxin (TA) systems, were identified on the mobile genetic elements (MGEs) of LC. Conclusively, in addition to the common VFs, various unique MGE-borne VFs, including the Yen-Tc cluster, TA components, and multiple chromosome-encoded chitinase genes, may contribute to the full spectrum of LC virulence. Moreover, V. parahaemolyticus demonstrates host-specific virulence, which potentially drives the origin and spread of pathogenic factors.

Occurrence of Multispecies Myxozoan Parasite Infestation by Genus &lt;i&gt;Thelohanellus&lt;/i&gt; Kudo, 1933 in a Group of &lt;i&gt;Labeo rohita &lt;/i&gt;(Hamilton, 1822)

We describe two Thelohanellus Kudo spp. namely, T. bifurcata (34.94x 8.9μm) on gills and T. caudatus (13x8.9μm) on the caudal and dorsal fins, found infecting Labeo rohita (Hamilton, 1822) fingerlings in a wet lab facility of West Bengal India. The L. rohita fingerlings having spores on fins and gills were segregated and gross pathology was observed for one month. It was done to characterise the morphology of mature spores and to examine the histopathology of infected gills. There were 5-6 white cysts (1-2 mm in length) on the gill filament that were mostly persistent during the one-month study period and infected fish (12.5% prevalent) were listless, anorexic, and emaciated before eventually all of them perished. Spores of 4- 7 mm size in 1-4 numbers were found on caudal and dorsal fins which were visible for two weeks before it gets mature and released, whereas infected fish (20%) were active and underwent normal growth. Additionally, it was discovered that 5% of fingerlings had cysts on their gills and fins. The distal tip of the primary gill lamellae is where the gill epithelium ruptures, releasing the spores. The histological inspection of the infected gill clearly demonstrates infective sporoplasm entry, presporogonic stage, plasmodial maturation, and release of spores. Within a month, it was discovered that 100% of the fingerlings with infected gills died. This is because the plasmodial spores on primary gill filaments damage the structural framework of the gill filament and cause epithelial and vascular cell displacement. Our comparative analysis with previous studies support that orders and families of the parasites are strongly correlated with Thellohanellus Kudo sp: a pathogenic strain of T. bifurcata and a non-pathogenic strain of T. caudatus infecting L. rohita. The spore-forming stages of the gill-damaging T. bifurcata (entry, pre-sporogonic, and sporogonic) are extremely pathogenic to fish fingerlings and cause significant damage to gill tissue

Tetracycline resistance in Listeria monocytogenes and L. innocua from wild black bears (Ursus americanus) in the United States is mediated by novel transposable elements.

Listeria monocytogenes causes severe foodborne illness and is the only human pathogen in the genus Listeria. Previous surveys of AMR in Listeria focused on clinical sources and food or food processing environments, with AMR in strains from wildlife and other natural ecosystems remaining under-explored. We analyzed 185 sequenced strains from wild black bears (Ursus americanus) from the United States, including 158 and 27 L. monocytogenes and L. innocua, respectively. Tetracycline resistance was the most prevalent resistance trait. In L. monocytogenes, it was encountered exclusively in serotype 4b strains with the novel Tn916-like element Tn916.1039. In contrast, three distinct, novel tetracycline resistance elements (Tn5801.UAM, Tn5801.551, and Tn6000.205) were identified in L. innocua. Interestingly, Tn5801.551 was identical to elements in L. monocytogenes from a major foodborne outbreak in the United States in 2011. The findings suggest the importance of wildlife and non-pathogenic Listeria species as reservoir for resistance elements in Listeria.

Extraction of Fish Collagen Peptides from Fish Waste through Fermentation using Lactobacillus Bacteria

Objective: To introduce a novel technique for extracting fish collagen peptides from fish waste. It could be a cheap and safe technique for obtaining peptides of fish as well as reducing the fish waste environmental load.Study Design: A comparative study.Place and Duration of Study: The study was conducted at Department of Microbiology, Hazara University Mansehra, Khyber Pakhtunkhwa and National University of Medical Sciences, Rawalpindi, Pakistan from August 2020 to July 2022.Methods: For the extraction of the fish collagen peptides, lactobacillus bacteria fermentation was being performed, in which the bacteria from yogurt and dough were added to fish samples and incubated for one month at 30°C. Lactobacillus bacteria were diluted with serial dilution for colonies isolation and biochemical characterization. Fish waste was cut in small pieces and put in a bottle containing distilled water and lactobacillus bacteria species and kept at 30°C for one month. The Hestrin–Schramm media (HS) was added in small amount as a starter for initial growth of bacteria. The pH was analyzed after every 7 days and 5–10 ml sample was collected from each labelled flask. The collected samples were precipitated using Trichloroacetic acid (TCA) and analyzed on SDS-PAGE.Results: Gel analysis revealed different size of fish collagen with higher concentration include the pattern for α1 and α2 chains with a molecular weight of 145 kDa and 132 kDa, respectively. The biological activity of extracted fish collagen was determined by using HaCaT cells proliferation analysis.Conclusion: The current study concluded that fish waste could be converted to biofunctional collagen using nonpathogenic strains of lactobacillus bacteria for various biomedical applications.&#x0D; How to cite this: Khan S, Tauseef I, Ikram M, Rauf S, Saeed RF, Sadiqi S, Lone NA, Ali L, Subhan F. Extraction of Fish Collagen Peptides from Fish Waste Through Fermentation Using Lactobacillus Bacteria. Life and Science. 2023; 4(4): 365-371. doi: http://doi.org/10.37185/LnS.1.1.423

Gut microbiota of Pacific white shrimp (Litopenaeus vannamei) exhibits distinct responses to pathogenic and non-pathogenic Vibrio parahaemolyticus.

Acute hepatopancreatic necrosis disease (AHPND), a high-mortality-rate shrimp disease, is caused by specific Vibrio parahaemolyticus (Vp) strains with a plasmid encoding the PirABVp toxins. As a bacterial pathogen, the invasion of AHPND-causing Vp might impose pressure on commensal microbiota in the shrimp gut, while the relationship between the pathogenesis of AHPND and the dysbiosis of gut bacterial communities remains unclear. Here we explored the temporal changes of shrimp gut microbiota in response to AHPND-causing and non-AHPND-causing Vp strains, with the non-infected controls as a baseline of the shrimp gut microbiota. The diversity and composition of bacterial communities from 168 gut samples (covering three treatments at seven time points with eight individuals per set) were investigated using 16S rRNA gene metabarcoding with high-throughput sequencing. The results showed that (i) species diversity of gut bacterial communities declined in Vp-infected shrimp, independent of the strain pathogenicity; (ii) taxonomic compositions of gut bacterial communities were significantly different between shrimp infected by AHPND-causing and non-AHPND-causing Vp strains; (iii) short-term (within 6 hours) compositional shifts in the gut microbiota were found only in AHPND-causing Vp-infected shrimp; (iv) the gut microbiota of AHPND-causing Vp-infected shrimp was enriched with genera Photobacterium and Vibrio, with a decline in Candidatus Bacilliplasma; and (v) functional predictions suggested the loss of normal metabolism due to compositional shifts in the gut microbiota. Our work reveals distinct features of community dynamics in shrimp gut microbiota, associated with pathogenic versus non-pathogenic Vibrio infections, providing a new perspective of the pathogenesis of AHPND. IMPORTANCE Shrimp production is continually threatened by newly emerging diseases, such as AHPND, which is caused by specific Vp strains. Previous studies on the pathogenesis of AHPND have mainly focused on the histopathology and immune responses of the host. However, more attention needs to be paid to the gut microbiota, which acts as the first barrier to pathogen colonization. In this study, we revealed that shrimp gut microbiota responded differently to pathogenic and non-pathogenic Vp strains, with bacterial genera Photobacterium and Vibrio enriched in pathogenic Vp-infected shrimp, and Candidatus Bacilliplasma enriched in non-pathogenic Vp-infected shrimp. Moreover, functional predictions suggested that changes in taxonomic compositions would further affect normal metabolic functions, emphasizing the importance of sustaining an equilibrium in the gut microbiota. Several biomarkers associated with specific microbial taxa and functional pathways were identified in our data sets, which help predict the incidence of disease outcomes.

A modern view of diarrheagenic &lt;i&gt;Escherichia coli&lt;/i&gt; — a causative agent of acute intestinal infections

Acute intestinal infections caused by Escherichia coli affect the gastrointestinal tract, leading to development of diarrheal syndrome, intoxication, and, in some cases, generalization of the pathological process. Diarrheagenic E. coli (DEC) strains differ from non-pathogenic (commensal) strains by the presence of specific virulence genes, pathogenesis characteristics, clinical and epidemiological manifestations of the diseases they cause. Based on the virulence determinants, 6 pathogenic DEC groups are distinguished: enteropathogenic, enterotoxigenic, enteroinvasive, shiga toxin-producing, enteroaggregative, diffusely adherent E. coli strains. The strains of each pathogenic group have distinct pathogenic mechanisms responsible for inflammatory processes in different compartments of the human intestine, which are clinically manifested as diarrheal syndrome. This paper presents a review of current scientific publications on epidemiology, pathogenesis, genetic properties, and antigenic characteristics of pathogenic E. coli. Although DEC biological properties have been extensively studied, many aspects require deeper insights to develop effective laboratory-based diagnostic techniques, treatment methods, epidemic control measures, and prevention strategies against E. coli infections.

Influence of pH on Inulin Conversion to 2,3-Butanediol by Bacillus licheniformis 24: A Gene Expression Assay.

2,3-Butanediol (2,3-BD) is an alcohol highly demanded in the chemical, pharmaceutical, and food industries. Its microbial production, safe non-pathogenic producer strains, and suitable substrates have been avidly sought in recent years. The present study investigated 2,3-BD synthesis by the GRAS Bacillus licheniformis 24 using chicory inulin as a cheap and renewable substrate. The process appears to be pH-dependent. At pH 5.25, the synthesis of 2,3-BD was barely detectable due to the lack of inulin hydrolysis. At pH 6.25, 2,3-BD concentration reached 67.5 g/L with rapid hydrolysis of the substrate but was accompanied by exopolysaccharide (EPS) synthesis. Since inulin conversion by bacteria is a complex process and begins with its hydrolysis, the question of the acting enzymes arose. Genome mining revealed that several glycoside hydrolase (GH) enzymes from different CAZy families are involved. Five genes encoding such enzymes in B. licheniformis 24 were amplified and sequenced: sacA, sacB, sacC, levB, and fruA. Real-time RT-PCR experiments showed that the process of inulin hydrolysis is regulated at the level of gene expression, as four genes were significantly overexpressed at pH 6.25. In contrast, the expression of levB remained at the same level at the different pH values at all-time points. It was concluded that the sacC and sacA/fruA genes are crucial for inulin hydrolysis. They encode exoinulinase (EC 3.2.1.80) and sucrases (EC 3.2.1.26), respectively. The striking overexpression of sacB under these conditions led to increased synthesis of EPS; therefore, the simultaneous production of 2,3-BD and EPS cannot be avoided.

Development of a novel target-based cell assay, reporter of the activity of Mycobacterium tuberculosis protein-O-mannosyltransferase.

The Protein-O-mannosyltransferase is crucial for the virulence of Mycobacterium tuberculosis, the etiological agent of tuberculosis. This enzyme, called MtPMT (Rv1002c), is responsible for the post-translational O-mannosylation of mycobacterial proteins. It catalyzes the transfer of a single mannose residue from a polyprenol phospho-mannosyl lipidic donor to the hydroxyl groups of selected Ser/Thr residues in acceptor proteins during their translocation across the membrane. Previously, we provided evidence that the loss of MtPMT activity causes the absence of mannoproteins in Mycobacterium tuberculosis, severely impacting its intracellular growth, as well as a strong attenuation of its pathogenicity in immunocompromised mice. Therefore, it is of interest to develop specific inhibitors of this enzyme to better understand mycobacterial infectious diseases. Here we report the development of a "target-based" phenotypic assay for this enzyme, assessing its O-mannosyltransferase activity in bacteria, in the non-pathogenic Mycobacterium smegmatis strain. Robustness of the quantitative contribution of this assay was evaluated by intact protein mass spectrometry, using a panel of control strains, overexpressing the MtPMT gene, carrying different key point-mutations. Then, screening of a limited library of 30 compounds rationally chosen allowed us to identify 2 compounds containing pyrrole analogous rings, as significant inhibitors of MtPMT activity, affecting neither the growth of the mycobacterium nor its secretion of mannoproteins. These molecular cores could therefore serve as scaffold for the design of new pharmaceutical agents that could improve treatment of mycobacterial diseases. We report here the implementation of a miniaturized phenotypic activity assay for a glycosyltransferase of the C superfamily.

Discovery of novel reversible inhibitor of DprE1 based on benzomorpholine for the treatment of tuberculosis.

About a quarter of the world's population is infected with Mycobacterium tuberculosis, equivalent to about two billion people. With the emergence of multidrug-resistant tuberculosis, those existing anti-tuberculosis drugs no longer meet the demand for cure anymore; there is an urgent need for the development of new anti-tuberculosis drugs. Decaprenylphosphoryl-β-D-ribose 2´-epimerase (DprE1) has been proven to be a potential antimycobacterial target, and several inhibitors have entered clinical trial. Herein, we designed and synthesized a series of compounds based on the indole and benzomorpholine by using the strategy of scaffold hopping. The preferred compound B18 showed strong antimycobacterial activity in H37Rv and drug-resistant clinical isolates. In addition, compound B18 did not exhibit antimycobacterial efficacy against other species of strains. Subsequently, the target of B18 was identified as DprE1 by analyzing spontaneous compound-resistant mutation data, and a docking study was performed to illustrate the binding mode between B18 and DprE1. In general, compound B18 is compatible to current DprE1 inhibitors, even higher phosphodiesterase 6C selectivity and plasma protein binding rate, which represent a new type of effective reversible DprE1 inhibitor. IMPORTANCE Drug therapy remains the cornerstone of tuberculosis (TB) treatment, yet first-line anti-tuberculosis drugs are associated with significant adverse effects that can compromise patient outcomes. Moreover, prolonged and widespread use has led to an alarming rise in drug-resistant strains of Mycobacterium tuberculosis, including multidrug-resistant [MDR-tuberculosis (TB)] and extensively drug-resistant (XDR-TB) forms. Urgent action is needed to develop novel anti-tuberculosis agents capable of overcoming these challenges. We report that compound B18, a decaprenylphosphoryl-β-D-ribose 2´-epimerase inhibitor with a benzomorpholine backbone, exhibits potent activity against not only the non-pathogenic strain H37Ra, but also the pathogenic strain H37Rv and clinical MDR and XDR strains. Preliminary druggability studies indicate that B18 possesses high safety and acceptable pharmacokinetic properties, rendering it a promising candidate for further development as a novel anti-tuberculosis agent.

Furancarboxylate Coordination Polymers of Gd3+ and Eu3+: Synthesis, Structural Variations, and Biological Properties

A series of polymer complexes of Gd(III) and Eu(III) with 3-furancarboxylic (HFur) and 5-nitro-2-furancarboxylic (HNfur) acids differed in the composition and coligands presented by solvent molecules(CH3OH/C2H5OH/H2O) is synthesized: [Gd(Fur)3(CH3OH)(C2H5OH)]n (I), [Gd(Nfur)3(CH3OH)2]n·CH3CN (II), [Eu(Fur)3(C2H5OH)]n (III), and [Eu(Nfur)3(H2O)2]n·3CH3CN (IV). According to the X-raydiffraction (XRD) data, all complexes are 1D coordination polymers in which the lanthanide cation has thecoordination number 8 (LnO8) to form the environment as a doubly augmented triangular prism (I, II) or asquare antiprism (III, IV). The supramolecular levels of the polymers are stabilized due to intra- and intermolecularhydrogen bonds between the coordinated solvent molecules and O atoms of the chelate-boundanions of the acid and via two types of noncovalent C–H…O and N–O…π interactions that significantly contributeto an additional stabilization of the crystal packings. The biological properties of complexes I, II, andIV are studied with respect to the model nonpathogenic strain Mycolicibacterium smegmatis.