Bacterial Strains Research Articles

Improved complete genome sequence of Bdellovibrio bacteriovorus 109J, a widely studied laboratory strain of predatory bacteria.

The complete genome sequence of Bdellovibrio bacteriovorus 109J, a well-studied laboratory strain of predatory bacteria, first determined in 2014. Here we report an improved complete genome sequence of B. bacteriovorus 109J, incorporating 16 assembly and 87 nucleotide corrections. This revised genome will be helpful to studies on the predatory bacteria.

Reaction-Induced Self-Assembly of Polymyxin Mitigates Cytotoxicity and Reverses Drug Resistance.

Polymyxins have been regarded as an efficient therapeutic against many life-threatening, multidrug resistant Gram-negative bacterial infections; however, the cytotoxicity and emergence of drug resistance associated with polymyxins have greatly hindered their clinical potential. Herein, the reaction-induced self-assembly (RISA) of polymyxins and natural aldehydes in aqueous solution is presented. The resulting assemblies effectively mask the positively charged nature of polymyxins, reducing their cytotoxicity. Moreover, the representative PMBA4 (composed of polymyxin B (PMB) and (E)-2-heptenal (A4)) assemblies demonstrate enhanced binding to Gram-negative bacterial outer membranes and exhibit multiple antimicrobial mechanisms, including increased membrane permeability, elevated bacterial metabolism, suppression of quorum sensing, reduced ATP synthesis, and potential reduction of bacterial drug resistance. Remarkably, PMBA4 assemblies reverse drug resistance in clinically isolated drug-resistant strains of Gram-negative bacteria, demonstrating exceptional efficacy in preventing and eradicating bacterial biofilms. PMBA4 assemblies efficiently eradicate Gram-negative bacterial biofilm infections in vivo and alleviate inflammatory response. This RISA strategy offers a practical and clinically applicable approach to minimize side effects, reverse drug resistance, and prevent the emergence of resistance associated with free polymyxins.

Congregibacter variabilis sp. nov. and Congregibacter brevis sp. nov. Within the OM60/NOR5 Clade, Isolated from Seawater, and Emended Description of the Genus Congregibacter.

Two Gram-stain-negative, aerobic, motile by means of flagella, short rod-shaped bacterial strains, designated IMCC43200T and IMCC45268T, were isolated from coastal seawater samples collected from the South Sea of Korea. Strains IMCC43200T and IMCC45268T shared 98.6% 16S rRNA gene sequence similarity and were closely related to Congregibacter litoralis KT71T (98.8% and 98.7%, respectively). Complete whole-genome sequences of IMCC43200T and IMCC45268T were 3.93 and 3.86 Mb in size with DNA G + C contents of 54.8% and 54.2%, respectively. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 74.5% and 23.4%, respectively, revealing that they are independent species. The two strains showed ANI values of ≤ 75.8% and dDDH values of ≤ 23.0% to the type and only species of the genus Congregibacter (C. litoralis), indicating that each strain represents a novel species. Both strains contained summed feature 3 (comprising C16:1 ω6c and/or C16:1 ω7c) and summed feature 8 (comprising C18:1 ω6c and/or C18:1 ω7c) as major fatty acid constituents. The predominant isoprenoid quinone detected in both strains was ubiquinone-8 (Q-8). The major polar lipids of the two strains were phosphatidylethanolamine, phosphatidylglycerol, phospholipids, and aminolipids. Based on the phylogenetic, genomic, and phenotypic characterization, strains IMCC43200T and IMCC45268T were considered to represent two novel species within the genus Congregibacter, for which the names Congregibacter variabilis sp. nov. and Congregibacter brevis sp. nov. are proposed with IMCC43200T (= KCTC 8133T = NBRC 116295T = CCTCC AB 2023139T) and IMCC45268T (= KCTC 92921T = NBRC 116135T) as the type strains, respectively.

Proteus mirabilis and Klebsiella variicola associated with onion bacterial streak and bulb rot

The bulb onion (Allium cepa) is second only to tomatoes in value of vegetable crops cultivated worldwide. Water-soaked lesions, bleaching and blight on leaves and slippery skin, sour skin, soft rot near the neck and centre rot on onion bulbs were observed in surveys of the onion fields, storage as well as fruit and vegetable markets of northwestern provinces of Iran in 2020. Thirty-four samples were collected from onion fields of East Azerbaijan, West Azerbaijan and Zanjan provinces and the central storage of Bonab city. Fifty bacterial strains were isolated from symptomatic samples. Pathogenicity of the strains was confirmed by inoculating on onion bulb cultivars Azarshahr and Ghermez Anari. Twenty-eight strains were able to induce soft rot on the inoculated sites of cut onion bulbs. Onion bulbs turned dark brown at lesion sites and became odorous over time. All pathogenic strains were Gram-negative, facultative aerobic and catalase positive. Strains mainly varied in starch and aesculin hydrolysis, potato rot and hypersensitive reaction. Pathogenic strains separated into four groups based on phenotypic assays. In the phylogenetic tree based on concatenated sequences of gyrB and infB genes, the strains were divided into four clusters containing the type strains of Enterobacter ludwigii, Klebsiella variicola, Proteus mirabilis and Pantoea agglomerans, confirming their identity as belonging to these four species. This is the first report of P. mirabilis as a plant pathogen and of K. variicola as a causal agent of onion bulb rot. Moreover, this is the first report of E. ludwigii and P. agglomerans associated with onion bulb rot in Iran.

Whole-genome sequencing of multidrug-resistant Escherichia coli causing urinary tract infection in an immunocompromised patient: a case report

BackgroundEscherichia coli is a major human pathogen responsible for a broad range of clinical illnesses. It has been linked to endemic and epidemic nosocomial diseases caused by multidrug-resistant pathogens in Sudan as well as throughout the globe.Case presentationA 76-year-old African woman arrived at Saad Rashwan Medical Centre complaining of backaches and discomfort during urination. Throughout the preceding 5 years, the patient had recurrent urinary tract infections. Following overnight incubation at 37 °C, Escherichia coli was found in her midstream urine specimen on cysteine lactose electrolyte deficient agar media. Minimum inhibitory concentration (colorimetric/turbidimetric method) was employed to test a wide range of antimicrobial drugs against this bacterial strain, and the results revealed significant multidrug resistance. QIAamp® DNA Mini Kit was used to obtain DNA Template from the purified Escherichia coli (Qiagen, Hilden, Germany). The bacterial whole-genome sequence was done by Novogene company (Hong Kong) using Illumina HiSeq 2500 (Illumina, San Diego, CA, USA), followed by whole genome reconstructions, and identification of antibiotic-resistant genes. Phylogenetic analysis revealed that our strain was related to the Escherichia coli DSM30083 ( genome sequence ID: CP033092.2) from the USA. Our strain possessed the following antimicrobial-resistant genes: aminoglycoside (kdpE, baeR, cpxA, aadA5), nitroimidazole (msbA), phosphonic acid (mdtG), tetracycline (emrY), macrolide, penam, tetracycline, (evgA, TolC, H-NS), fluoroquinolone, cephalosporin, glycylcycline, penam, tetracycline, rifamycin, phenicol antibiotic, disinfecting agents and antiseptics (acrB; marA), sulfonamide (sul1), macrolide (Mrx), cephalosporin, penam (CTX-M-15), carbapenem, cephalosporin, and penam (OXA-1).ConclusionThis study found that the isolated Escherichia coli strain had varied antimicrobial resistance genes on the basis of whole-genome sequencing and phenotypic resistance analyses. Whole-genome sequencing is critical for control and preventative methods to battle the growing threat of antimicrobial resistance. A larger investigation is recommended for improved generalization of results.

Chemoenzymatic Modification of Daptomycin: Aromatic Group Installation on Trp1.

Daptomycin is a cyclic lipodepsipeptide antibiotic used to treat infections caused by Gram-positive pathogens, including multi-drug resistant strains such as methicillin-resistant Staphylococcus au-reus (MRSA) and vancomycin-resistant enterococci (VRE). The emergence of daptomycin-resistant bacterial strains has renewed interest in generating daptomycin analogs. Previous studies have shown that replacing the tryptophan of daptomycin with aromatic groups can generate analogs with enhanced potency. Additionally, we have demonstrated that aromatic prenyltransferases can attach diverse groups to the tryptophan of daptomycin. Here, we report the use of the prenyltransferase CdpNPT to derivatize the tryptophan of daptomycin with a library of benzylic and heterocyclic pyrophosphates. An analytical-scale study revealed that CdpNPT can transfer various aromatic groups onto daptomycin. Subsequent scaled-up and purified reactions indicated that the enzyme can attach aromatic groups to N1, C2, C5 and C6 positions of Trp1 of daptomycin. In vitro antibacterial activity assays using six of these purified compounds identified aromatic substituted daptomycin analogs show potency against both daptomycin-susceptible and resistant strains of Gram-positive bacteria. These findings suggest that installing aromatic groups on the Trp1 of daptomycin can lead to the generation of potent daptomycin analogs.

Developed Rhizobium Strains Enhance Soil Fertility and Yield of Legume Crops in Haryana, India.

Three strains of Gram-negative bacterium,Rhizobium, were developed by gamma (γ)-irradiation random mutagenesis. The developed strains were evaluated for their augmented features for symbiotic association, nitrogen fixation, and crop yield of three leguminous plants-chickpea, field-pea, and lentil-in agricultural fields of the northern Indian state of Haryana. Crops treated with developed mutants exhibited significant improvement in plant features and the yield of crops when compared to the control-uninoculated crops and crops grown with indigenous or commercial crop-specific strains of Rhizobium. This improvement was attributed to generated mutants, MbPrRz1 (on chickpea), MbPrRz2 (on lentil), and MbPrRz3 (on field-pea). Additionally, the cocultured symbiotic response of MbPrRz1 and MbPrRz2 mutants was found to be more pronounced on all three crops. The statistical analysis using Pearson's correlation coefficientsrevealed that nodulation and plant biomass were the most related parameters of crop yield. Among the effectiveness of developed mutants, MbPrRz1 yielded the best results for all three tested crops. Moreover, the developed mutants enhanced macro- and micronutrients of the experimental fields when compared with fields harboring the indigenous rhizobial community. These developed mutants were further genetically characterized, predominantly expressing nitrogen fixation marker, nifH, and appeared to belong to Mesorhizobium ciceri (MbPrRz1) and Rhizobium leguminosarum (both MbPrRz2 and MbPrRz3). In summary, this study highlights the potential of developed Rhizobium mutants as effective biofertilizers for sustainable agriculture, showcasing their ability to enhance symbiotic relationships, crop yield, and soil fertility.

Synthesis, Characterization and Evaluation of Antibacterial activity of Amine-Boranes

Amine-Boranes (AB) are an elite class of reagent and belongs to the Borane-Lewis family, has found extensive use in chemical synthesis. Interesting aspect of AB reagents are to display chemo selectivity among the functional groups. The present investigation highlights on the innovative, green synthesis and characterization of the three of unique AB complexes, including triethylamine-borane (aliphatic), aniline-borane (aromatic), and (aromatic substituted) N,N-dimethylaniline-borane (DMAB) under an open air condition. The 11B NMR technique was used to characterize the synthesized AB reagents. The chemical shift values obtained were in accordance with the results of previous research studies, and it's interesting to note that there is a difference in 11B-NMR chemical shift values between the borane complexes of aromatic and aliphatic amines. The antibacterial efficacy of three AB reagents has been stated for the first instance by using disc diffusion method against four bacterial strains: Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, and Staphylococcus aureus. When compared to other AB complexes, the DMAB reagent demonstrated significant antibacterial properties against the four different bacterial species.

Effects of Hexagonal Boron Nitride and Mesoporous Silica Nanoparticles on the Morphology, Mechanical Properties and Antimicrobial Activity of Dental Composites

AbstractHexagonal boron nitride (HBN), an artificial material with unique properties, is used in many industries. This article focuses on the extent to which hexagonal boron nitride and silica nanoparticles (MSN) affect the physicochemical and mechanical properties and antimicrobial activity of prepared dental composites. In this study, HBN, and MSN were used as additives in dental composites. 5% and 10% by weight of HBN are added to the structure of the composite materials. FTIR analysis were performed to determine the components of the produced boron nitride powders, hexagonal boron nitride-containing composites, and filling material applications. The structural and microstructural properties of dental composites have been extensively characterized using X-ray diffractometry (XRD). Surface morphology and distributions of nano boron nitride were determined by scanning electron microscopy (SEM)-EDS. In addition, the solubility of dental composites in water and their stability in water and chemical solution (Fenton) were determined by three repetitive experiments. Finally, the antimicrobial activity of dental composites was detected by using Minimum Inhibitory Concentration (MIC) measurement, as well as Minimum Fungicidal Concentration (MFC) method against yeast strain Saccharomyces cerevisiae, and Minimum Bactericidal Concentration (MBC) method against bacteria strains, Staphylococcus aureus and Escherichia coli. Since the HMP series have better antimicrobial activity than the HP series, they are more suitable for preventing dental caries and for long-term use of dental composites. In addition, when HMP and HP series added to the composite are compared, HMP-containing dental composites have better physicochemical and mechanical properties and therefore have a high potential for commercialization.

Physical cell-cell contact elicits specific transcriptomic responses in wine yeast species.

Fermenting grape juice provides a habitat for a well-mapped and evolutionarily relevant microbial ecosystem consisting of many natural or inoculated strains of yeasts and bacteria. The molecular nature of many of the ecological interactions within this ecosystem remains poorly understood, with the partial exception of interactions of a metabolic nature such as competition for nutrients and production of toxic metabolites/peptides. Data suggest that physical contact between species plays a significant role in the phenotypic outcome of interspecies interactions. However, the molecular nature of the mechanisms regulating these phenotypes remains unknown. Here, we present a transcriptomic analysis of physical versus metabolic contact between two wine relevant yeast species, Saccharomyces cerevisiae and Lachancea thermotolerans. The data show that these species respond to the physical presence of the other species. In S. cerevisiae, physical contact results in the upregulation of genes involved in maintaining cell wall integrity, cell wall structural components, and genes involved in the production of H2S. In L. thermotolerans, HSP stress response genes were the most significantly upregulated gene family. Both yeasts downregulated genes belonging to the FLO family, some of which play prominent roles in cellular adhesion. qPCR analysis indicates that the expression of some of these genes is regulated in a species-specific manner, suggesting that yeasts adjust gene expression to specific biotic challenges or interspecies interactions. These findings provide fundamental insights into yeast interactions and evolutionary adaptations of these species to the wine ecosystem.IMPORTANCEWithin the wine ecosystem, yeasts are the most relevant contributors to alcoholic fermentation and wine organoleptic characteristics. While some studies have described yeast-yeast interactions during alcoholic fermentation, such interactions remain ill-defined, and little is understood regarding the molecular mechanisms behind many of the phenotypes observed when two or more species are co-cultured. In particular, no study has investigated transcriptional regulation in response to physical interspecies cell-cell contact, as opposed to the generally better understood/characterized metabolic interactions. These data are of direct relevance to our understanding of microbial ecological interactions in general while also creating opportunities to improve ecosystem-based biotechnological applications such as wine fermentation. Furthermore, the presence of competitor species has rarely been considered an evolutionary biotic selection pressure. In this context, the data reveal novel gene functions. This, and further such analysis, is likely to significantly enlarge the genome annotation space.

The functional identification and evaluation of endophytic bacteria sourced from the roots of tolerant Achyranthes bidentata to overcome monoculture problems of Rehmannia glutinosa

The isolation and identification of plant growth-promoting endophytic bacteria (PGPEB) from Achyranthes bidentata roots have profound theoretical and practical implications in ecological agriculture, particularly as bio-inoculants to address challenges associated with continuous monoculture. Our research revealed a significant increase in the abundance of these beneficial bacteria in A. bidentata rhizosphere soil under prolonged monoculture conditions, as shown by bioinformatics analysis. Subsequently, we isolated 563 strains of endophytic bacteria from A. bidentata roots. Functional characterization highlighted diverse plant growth-promoting traits among these bacteria, including the secretion of indole-3-acetic acid (IAA) ranging from 68.01 to 73.25 mg/L, phosphorus and potassium solubilization capacities, and antagonistic activity against pathogenic fungi (21.54%−50.81%). Through 16S rDNA sequencing, we identified nine strains exhibiting biocontrol and growth-promoting potential. Introduction of a synthetic microbial consortium (SMC) in pot experiments significantly increased root biomass by 48.19% in A. bidentata and 27.01% in replanted Rehmannia glutinosa. These findings provide innovative insights and strategies for addressing continuous cropping challenges, highlighting the practical promise of PGPEB from A. bidentata in ecological agriculture to overcome replanting obstacles for non-host plants like R. glutinosa, thereby promoting robust growth in medicinal plants.

The effect of free and encapsulated probiotic bacteria on some physicochemical, microbiological, and textural properties of apricot leather (pestil) during storage.

Pestil, also known as fruit leather, has emerged as a promising non-dairy carrier for probiotics, utilizing apricots and incorporating probiotics into its formulation. This study aimed to develop a healthy snack bar by incorporating three distinct strains of probiotic bacteria, both in free and encapsulated forms, into the recipe of apricot leather. The physicochemical, bioactive, microbiological, and textural attributes of the resulting apricot pestils were evaluated over a 120-day storage period. Fluctuations in pH (4.74-4.97) were observed during storage, whereas water activity (0.31-0.45) and moisture content (8.05%-13.40%) exhibited a decreasing trend over time. Incorporating free or encapsulated bacteria resulted in a darker surface, attributed to the intermolecular interactions between probiotics and the pestil matrix. The initial total phenolic content was highest and declined significantly during storage (52.13-291.73mg gallic acid equivalent/100g) (p<0.05). Viability was found to be higher in the encapsulated forms of bacteria at the conclusion of the storage period. Overall, apricot pestil emerged as a promising matrix for viable probiotics, facilitating their delivery and hosting in both free and encapsulated forms during storage.

A novel exopolysaccharide-producing bacterium, Pseudescherichia liriopis sp. nov. isolated from Liriope platyphylla, enhances the growth of Daucus carota subsp. sativus under drought and salinity stress

Biological and abiotic stresses in plant growth are associated with reduced crop yields. Therefore, improving plant stress resistance can be a crucial strategy to improve crop production. To overcome these problems, plant growth-promoting bacteria are emphasized as one of the alternative tools for sustainable agriculture. This study found a novel strain (L3T) of a plant growth-promoting bacterium in fermented Liriope platyphylla fruit. Strain L3T showed the ability to promote plant growth. The L3T strain promoted plant growth of D. carota subsp. sativus, increasing the length (increase rate compared to the control group, 36.98%), diameter (47.06%), and weight of carrots (81.5%), ultimately increasing the edible area. In addition, we confirmed that plant growth was improved even in situations that inhibited plant growth, such as salinity and drought stress. Strain L3T performed indole production, siderophore production, phosphate solubilization, and nitrogen fixation, all characteristics of a strain that promotes plant growth. Genome analysis revealed genes involved in the growth promotion effects of strain L3T. Additionally, the properties of exopolysaccharides were identified and characterized using FTIR, TGA, and UHPLC. Our results demonstrated that L3 isolated from fermented L. platyphylla fruit can be used to simultaneously alleviate drought and NaCl stress.

Genome sequences of four bacterial strains isolated from organofluorine enrichment cultures.

Because fluorinated organic compounds are broadly used and highly persistent, microbes isolated from wastewater may be able to degrade these contaminants. Here, we report the genome sequences of Flavobacterium sp. str. WV_118_3, Nocardioides sp. str. WV_118_6, Ochrobactrum anthropi str. WV_118_8, and Sphingomonas sp. str. VL_57B, isolated from wastewater.

Design and evaluation of composite films for in situ synthesis and antibacterial activity of allicin vapour

AbstractAlthough allicin has potent antibiotic properties, its low stability, which is responsible for its persistent biological activity, has posed a significant challenge to its practical application in modern medicine. To harness the healing benefits of this phytochemical, known by humans for thousands of years, we propose a controlled in situ synthesis of allicin vapour near the site of infection. Considering the critical need for novel approaches to prevent pandemic scenarios caused by MDR bacteria, we suggest encapsulating and physically separating allicin precursors (substrate alliin and enzyme alliinase) in alginate-based films and spray-dried chitosan microparticles. The mechanical properties of the hydrogel films of various compositions were evaluated, as well as their ability to protect the encapsulated alliinase against thermal stress and control the overall rate of allicin release upon hydration. Furthermore, the non-contact antibacterial efficacy of free alliin/alliinase reaction mixture (aqueous solution) and three compartmentalised configurations, i.e. film-solution, film-particles, and double-film, were tested against selected bacterial strains, i.e. E. coli, S. epidermidis, and S. aureus. The results indicate that the formation of allicin vapour using the proposed compartmentalised systems addresses allicin’s stability issues and provides better control over the rate of allicin production. The observed antibacterial effect was comparable with directly formed allicin using higher initial amounts of both substances, which is given by diffusion limitations associated with encapsulation. These findings illustrate the potential of compartmentalised systems in developing nature-based wound dressings for infection prevention and promoting healing.

L-carnitine co-administration prevents colistin-induced mitochondrial permeability transition and reduces the risk of acute kidney injury in mice

Colistin is a polymyxin antibiotic currently experiencing renewed clinical interest due to its efficacy in the treatment of multidrug resistant (MDR) bacterial infections. The frequent onset of acute dose-dependent kidney injury, with the potential of leading to long-term renal damage, has limited its use and hampered adequate dosing regimens, increasing the risk of suboptimal plasma concentrations during treatment. The mechanism of colistin-induced renal toxicity has been postulated to stem from mitochondrial damage, yet there is no direct evidence of colistin acting as a mitochondrial toxin. The aim of this study was to evaluate whether colistin can directly induce mitochondrial toxicity and, if so, uncover the underlying molecular mechanism. We found that colistin leads to a rapid permeability transition of mitochondria isolated from mouse kidney that was fully prevented by co-incubation of the mitochondria with desensitizers of the mitochondrial transition pore cyclosporin A or L-carnitine. The protective effect of L-carnitine was confirmed in experiments in primary cultured mouse tubular cells. Consistently, the relative risk of colistin-induced kidney damage, calculated based on histological analysis as well as by the early marker of tubular kidney injury, Kim-1, was halved under co-administration with L-carnitine in vivo. Notably, L-carnitine neither affected the pharmacokinetics of colistin nor its antimicrobial activity against relevant bacterial strains. In conclusion, colistin targets the mitochondria and induces permeability transition thereof. L-carnitine prevents colistin-induced permeability transition in vitro. Moreover, L-carnitine co-administration confers partial nephroprotection in mice treated with colistin, without interfering with its pharmacokinetics and antibacterial activity.

Polymer-Based Hydroxyapatite–Silver Composite Resin with Enhanced Antibacterial Activity for Dental Applications

The primary objective of this investigation was to synthesize a resin incorporating nanoparticles of hydroxyapatite and silver (HA-NpsAg) to enhance biocompatibility and antimicrobial efficacy, thereby facilitating potential implementation within the dental industry. These enhancements aim to ensure reliable, durable, functional, and aesthetically pleasing restorations while concurrently reducing susceptibility to bacterial colonization within the oral cavity. Hydroxyapatite powders were prepared using the sol–gel method and doped with silver nanoparticles obtained by chemical reduction. The crystalline amorphous calcium phosphate powder had a particle size of 279 nm, and the silver nanoparticles had an average diameter of 26.5 nm. Resin spheres containing HA-NpsAg (RHN) were then synthesized at two concentrations (0.5% and 1%) by dissolving the initial monomer mixture in tetrahydrofuran. Subsequent antimicrobial evaluations were conducted via agar diffusion and turbidimetry, employing three strains of Gram-negative bacteria (E. coli, K. oxytoca, and P. aeruginosa) and three strains of Gram-positive bacteria (S. mutans, S. aureus, and B. subtilis). The findings revealed that P. aeruginosa exhibited maximum susceptibility to RHN powder at a concentration of 0.5%, while RHN powder at 1% concentration demonstrated maximal inhibition against S. aureus and S. mutans. Overall, our study highlights the successful synthesis of a dental resin with hydroxyapatite and silver nanoparticles, exhibiting bactericidal properties at low silver concentrations. These findings hold promise for enhancing dental materials with improved antimicrobial efficacy and clinical performance.

Can Porphyrin-Triphenylphosphonium Conjugates Enhance the Photosensitizer Performance Toward Bacterial Strains?

Antimicrobial photodynamic treatment (aPDT) offers an alternative option for combating microbial pathogens, and in this way, addressing the challenges of growing antimicrobial resistance. In this promising and effective approach, cationic porphyrins and related macrocycles have emerged as leading photosensitizers (PS) for aPDT. In general, their preparation occurs via N-alkylation of nitrogen-based moieties with alkyl halides, which limits the ability to fine-tune the features of porphyrin-based PS. Herein, is reported that the conjugation of porphyrin macrocycles with triphenylphosphonium units created a series of effective cationic porphyrin-based PS for aPDT. The presence of positive charges at both the porphyrin macrocycle and triphenylphosphonium moieties significantly enhances the photodynamic activity of porphyrin-based PS against both Gram-positive and Gram-negative bacterial strains. Moreover, bacterial photoinactivation is achieved with a notable reduction in irradiation time, exceeding 50%, compared to 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP), used as the reference and known as good PS. The improved capability of the porphyrin macrocycle to generate singlet oxygen combined with the enhanced membrane interaction promoted by the presence of triphenylphosphonium moieties represents a promising approach to developing porphyrin-based PS with enhanced photosensitizing activity.

Development of Sourdough Bread Made with Probiotic Lactiplantibacillus plantarum Bacteria Addition

Bread is a staple in the diet of people around the world. A new solution is the addition of selected strains of bacteria to the sourdough to increase the quality of the obtained bread. In the presented research, seven bread samples were baked and analysed, which differed by the selected strain of bacteria of the Lactiplantibacillus plantarum species used in sourdough preparation. The bread was subjected to a 3-day ageing test. The structure of the products was analysed using the texture profile analysis (TPA) method on days 1 and 3 of storage. It was observed that the samples with the addition of selected L. plantarum bacterial strains underwent the process of staling much slower than the control sample. The analysis of the viability of lactic acid bacteria (LAB) in products after 1 and 3 days of storage was also performed. The obtained results indicate the highest survival rate of LAB in the control sample, i.e., the native microflora of baker’s starters, which was at 3.07 log CFU after one-day storage after baking. In the case of other samples, the viability of the bacteria was below 2.74 log CFU, which confirms a certain degree of thermostability of selected bacterial strains. The belonging of the isolated bacteria to the species L. plantarum was proven via genetic identification using the PCR method. A sensory analysis using the quantitative descriptive profile (QDP) method was also performed on the bread immediately after it was baked and cooled down. The analysis showed that the use of L. plantarum strains as starters did not significantly affect the aromatic and taste profiles of the samples compared to the control sample. The overall quality of the bread samples was high, above 6 units, with the control sample having the highest sensory quality of 7.5 units (on a scale of 0–10 units). The presented research suggests that it is possible to produce bread with bacteria that have health-promoting properties and good sensory quality, which enhances the textural features of the final product. Future research will focus on attempting to microencapsulate selected thermostable probiotic bacteria.

Impact of oligosaccharides on probiotic properties and B vitamins production: a comprehensive assessment of probiotic strains

SummaryFrom recent literature and research studies, it has been found that some bacterial strains have abilities with probiotic activities to produce B vitamins, which play essential roles in maintaining human health. Oligosaccharides can promote the beneficial microbes, however, the specific effects of oligosaccharides on B vitamins‐producing ability of probiotic strains have not been clarified. This study evaluated the effect of different oligosaccharides on the probiotic properties and B vitamin‐producing ability of 21 selected probiotic strains. The obtained results suggested that the strains could utilise oligosaccharides as the sole carbon source, and the hydrophobicity, auto‐aggregation, and biofilm formation of probiotic strains were specific regulated after fermentation with different oligosaccharides. In particular, the oligosaccharides had different influences on the levels of extracellular B vitamins produced by probiotic strains. These findings provide the foundation for studies on the B vitamins‐producing probiotic strains and their application in functional foods to prevent B vitamins deficiency.