Serratia Marcescens Strain Research Articles

Enhancement of serrawettin W1-producing Serratia marcescens cell migration by resonant oscillation under alternating current electric field

Swarming migration is observed in flagellated bacteria on wet surfaces. As the secreted biosurfactant hydrates, friction between the cell and the wet surface is reduced, and weak flagellar movement appears to be a significant force for cell translocation. Developing an artificial swarming control method could greatly aid in establishing techniques for biofilm inhibition and detachment. In this study, the effect of forced cell vibration by an alternating current electric field (ACEF) on swarming motility was investigated using the serrawettin W1-producing Serratia marcescens strain. At frequencies close to the natural frequencies of microbial cells (12 MHz), swarming motion was effectively enhanced in biosurfactant-producing S. marcescens, but not in non-surfactant-producing Escherichia coli or non-flagellated Staphylococcus aureus. Electric field-assisted cell migration was significantly induced under swarming conditions with low friction resistance between the cell and gel surface. This finding suggests a direction for developing strategies to regulate biofilm formation and detachment using ACEF-assisted oscillation of cells attached to surfaces.

A feasible approach for azo-dye (methyl orange) degradation by textile effluent isolate Serratia marcescens ED1 strain for water sustainability: AST identification, degradation optimization and pathway hypothesis

Methyl orange (MO) is a dye commonly used in the textile industry that harms aquatic life, soil and human health due to its potential as an environmental pollutant. The present study describes the dye degradation ability of Serratia marcescens strain ED1 isolated from textile effluent and characterized by 16S rRNA gene sequence analysis. The laccase property of bacterial isolate was confirmed qualitatively. The effects of various factors (pH, temperature, incubation time, and dye concentration) were evaluated using Response Surface Methodology (RSM). The maximum dye (MO) degradation was 81.02 % achieved at 37 °C temperature and 7.0 pH with 200 mg/L dye concentration after 48 h of incubation. The beef extract, ammonium nitrate and fructose supplementation showed better response during bioremediation among the different carbon and nitrogen sources. The degree of pathogenicity was confirmed through the simple plate-based method, and an antibiotic resistance profile was used to check the low-risk rate of antibiotic resistance. However, the fate and extinct of degraded MO products were analysed through UV–Vis spectroscopy, FT-IR, and GC-MS analysis to confirm the biodegradation potential of the bacterial strain ED1 and intermediate metabolites were identified to propose metabolic pathway. The phytotoxicity study on Vigna radiata L. seeds confirmed nontoxic effect of degraded MO metabolites and indicates promising degradation potential of S. marcescens strain ED1 to successfully remediate MO dye ecologically sustainably.

Biological Characterization and Genomic Analysis of Three Novel Serratia- and Enterobacter-Specific Virulent Phages.

Due to the high microbiological contamination of raw food materials and the increase in the incidence of multidrug-resistant bacteria, new methods of ensuring microbiological food safety are being sought. One solution may be to use bacteriophages (so-called phages) as natural bacterial enemies. Therefore, the aim of this study was the biological and genomic characterization of three newly isolated Serratia- and Enterobacter-specific virulent bacteriophages as potential candidates for food biocontrol. Serratia phage KKP_3708 (vB_Sli-IAFB_3708), Serratia phage KKP_3709 (vB_Sma-IAFB_3709), and Enterobacter phage KKP_3711 (vB_Ecl-IAFB_3711) were isolated from municipal sewage against Serratia liquefaciens strain KKP 3654, Serratia marcescens strain KKP 3687, and Enterobacter cloacae strain KKP 3684, respectively. The effect of phage addition at different multiplicity of infection (MOI) rates on the growth kinetics of the bacterial hosts was determined using a Bioscreen C Pro growth analyzer. The phages retained high activity in a wide temperature range (from -20 °C to 60 °C) and active acidity values (pH from 3 to 12). Based on transmission electron microscopy (TEM) imaging and whole-genome sequencing (WGS), the isolated bacteriophages belong to the tailed bacteriophages from the Caudoviricetes class. Genomic analysis revealed that the phages have linear double-stranded DNA of size 40,461 bp (Serratia phage KKP_3708), 67,890 bp (Serratia phage KKP_3709), and 113,711 bp (Enterobacter phage KKP_3711). No virulence, toxins, or antibiotic resistance genes were detected in the phage genomes. The lack of lysogenic markers indicates that all three bacteriophages may be potential candidates for food biocontrol.

Single-Step Low-Temperature Synthesis of Carbon Dots for Advanced Multiparametric Bioimaging Probe Applications.

Carbon dots (CDs) have recently emerged in biomedical and agricultural domains, mainly for their probe applications in developing efficient sensors. However, the existing high-temperature approaches limit the industrial level scaling up to further translate them into different products by mass-scale fabrication of CDs. To address this, we have attempted to lower the synthesis temperature to 140 °C and synthesized different CDs using different organic acids and their combinations in a one-step approach (quantum yield 3.6% to 16.5%; average size 3 to 5 nm). Further, sensing applications of CDs have been explored in three different biological models, mainly Danio rerio (zebrafish) embryos, bacterial strains, and the Lactuca sativa (lettuce) plant. The 72 h exposure of D. rerio embryos to 0.5 and 1 mg/mL concentrations of CDs exhibited significant uptake without mortality, a 100% hatching rate, and nonsignificant alterations in heart rate. Bacterial bioimaging experiments revealed CD compatibility with Gram-positive (Bacillus subtilis) and Gram-negative (Serratia marcescens) strains without bactericidal effects. Furthermore, CDs demonstrated effective conduction and fluorescence within the vascular system of lettuce plants, indicating their potential as in vivo probes for plant tissues. The single-step low-temperature CD synthesis approach with efficient structural and optical properties enables the process as industrially viable to up-scale the technology readiness level. The bioimaging of CDs in different biological models indicates the possibility of developing a CD probe for diverse biosensing roles in diseases, metabolism, microbial contamination sensing, and more.

Biotransformation characteristics of tetracycline by strain Serratia marcescens MSM2304 and its mechanism evaluation based on products analysis and genomics

Microbial biotransformation is a recommended and reliable method in face of formidable tetracycline (TC) with broad-spectrum antibacterial activity. Herein, comprehensive characteristics of a newfound strain and its molecular mechanism in process of TC bioremediation were involved in this study. Specifically, Serratia marcescens MSM2304 isolated from pig manure sludge grew well in presence of TC and achieved optimal removal efficiency of 61% under conditions of initial TC concentration of 10 mg/L, pH of 7.0, cell inoculation amount of 5%, and tryptone of 10 g/L as additional carbon. The pathways of biotransformation include EPS biosorption, cell surface biosorption and biodegradation, which enzymatic processes of biodegradation were occurred through TC adsorbed by biofilms was firstly broken down by extracellular enzymes and part of TC migrated towards biofilm interior and degraded by intracellular enzymes. Wherein extracellular polysaccharides in extracellular polymeric substances (EPS) from biofilm of strain MSM2304 mainly performed extracellular adsorption, and changes in position and intensity of CO, =CH and C–O–C/C–O of EPS possible further implied TC adsorption by it. Biodegradation accounting for 79.07% played a key role in TC biotransformation and could be fitted well by first-order model that manifesting rapid and thorough removal. Potential biodegradation pathway including demethylation, dihydroxylation, oxygenation, and ring opening possibly involved in TC disposal process of MSM2304, TC-degrading metabolites exhibited lower toxicity to indicator bacteria relative to parent TC. Whole genome sequencing as underlying molecular evidence revealed that TC resistance genes, dehydrogenases-encoding genes, monooxygenase-encoding genes, and methyltransferase-encoding genes of strain MSM2304 were positively related to TC biodegradation. Collectively, these results favored a theoretical evaluation for Serratia marcescens MSM2304 as a promising TC-control agent in environmental bioremediation processes.

Serratia marcescens LYGN1 Reforms the Rhizosphere Microbial Community and Promotes Cucumber and Pepper Growth in Plug Seedling Cultivation.

The vegetable plug seedling plays an important role in improving vegetable production. The process of plug seedling contributes to high-quality vegetable seedlings. The substrate composition and chemical fertilizer are widely studied to promote seedling growth. However, little is known about the effect of beneficial bacteria in the rhizosphere microbial community and vegetables' growth during plug seedling. The use of beneficial microbes to promote vegetable seedling growth is of great potential. In this study, we showed that the Serratia marcescens strain LYGN1 enhanced the growth of cucumber and pepper seedlings in plug seedling cultivation. The treatment with LYGN1 significantly increased the biomass and the growth-related index of cucumber and pepper, improving the seedling quality index. Specifically, LYGN1 also improved the cucumber and pepper root system architecture and increased the root diameter. We applied high-throughput sequencing to analyze the microbial community of the seedlings' rhizosphere, which showed LYGN1 to significantly change the composition and structure of the cucumber and pepper rhizosphere microbial communities. The correlation analysis showed that the Abditibacteriota and Bdellovibrionota had positive effects on seedling growth. The findings of this study provide evidence for the effects of Serratia marcescens LYGN1 on the cucumber and pepper rhizosphere microbial communities, which also promoted seedling quality in plug seedling cultivation.

Differential analysis of transcriptome of psychrophilic bacteria under different culture temperatures.

Psychrophilic bacteria can survive in a unique living environment. To explore the mechanism of low temperature adaptation and the physiological function of thermophilic metabolic genes. Serratia marcescens strain F13 stored in microbial laboratory was cultured at 5∘C, 10∘C and 25∘C respectively, and the obtained strains were sequenced by high-throughput transcriptome. Serratia marcescens strain CAV1761 was used as the reference strain. The data produced by transcriptome sequencing were statistically analyzed by biostatistics software such as soapnuke, soap and edger. The differentially expressed genes were found based on the gene expression, and analyzed by Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The results showed that there were 718 differential genes in F13-10 vs F13-5 comparison group, 1614 differential genes in F13-25 vs F13-5 comparison group and 1636 differential genes in F13-25 vs F13-10 comparison group. GO function enrichment analysis showed that the GO term mainly enriched by different genes in the three comparison groups was mostly related to the migration and transport of cellular or subcellular components, cell localization and transmembrane transporter activity, as well as cilia or flagella dependent cell movement. In the enrichment analysis of KEGG pathway, the three comparison groups all enriched the largest number of differential genes in the branch pathway of KEGG metabolism, followed by the branch pathway of environmental information processing. In F13-10 vs F13-5, the differential genes were mainly concentrated in 20 pathways such as ATP-binding cassette transport (ABC) transporters, thiamine metabolism and flagella assembly; In F13-25 vs F13-5, the differential genes are mainly concentrated in 20 pathways, such as (ABC) transporters, arginine and proline metabolism, two-component system and so on; In F13-25 vs F13-10, the differential genes are mainly concentrated in 20 pathways such as various types of glycan synthesis, two-component system and arginine metabolism.

Neonatal intensive care units: extended spectrum β-lactamase genes and biofilm formation by Serratia marcescens.

The increasing cases of bloodstream infections among children at neonatal intensive care units (NICUs) led this work to investigate biofilm production, antibiotics and the presence of ESβL genes in Serratia marcescens (S. marcescens) strains isolated from blood. Twenty S. marcescens strains were isolated and identified by the VITEK-2 system over 7months from late 2022 to mid-2023 from Ibn Al-Balady Hospital in Baghdad. Kirby-Bauer test was used to measure antibiotic susceptibility. The results revealed that 95% of twenty S. marcescens isolates were non-susceptible to Ampicillin and Amoxicillin-clavulanic. Furthermore, S. marcescens isolates showed a high sensitivity rate 70% toward Imipenem. All S. marcescens strains 100% were produced biofilm. This work clarifies that, out of 20 S. marcescens strains, 80% were harbored ESβL genes. The coexistence of blaTEM, blaCTX and blaSHV genes was shown in 43.75% of strains, while 56.25% of S. marcescens strains harbored single ES[Formula: see text]L genes. The biofilm values increase with the accuracy of EsβL genes. Phylogenetic analyses based on the sequence of blaCTX-M and blaTEM were done with closely related genes in the GenBank using MEGA6 software. The distribution of blaTEM, blaCTX and blaSHV genes among local S. marcescens strains may be attributed to the indiscriminate use of antibiotics. The results confirmed the spread of ESβL genes in S. marcescens from blood infections among newborn infants.

A Two-Level Factorial Design for Screening Factors that Influence the Decolorization of Congo Red by Serratia marcescens strain Neni-1

The toxicity and persistence of Congo Red pollution make it a major threat to both the environment and human health. Biodegradation, which involves the breakdown of pollutants by microbes like bacteria, fungi, and algae, is an attractive and long-term solution to the problem of Congo Red pollution. Optimization techniques such as Response Surface Methodology can further improve biodegradation processes' efficiency, but initial screening is often needed. Using a two-level factorial design, this study successfully screened five parameters (temperature, pH, incubation time, concentration of Congo Red, and sucrose) that affect Congo red's decolorization by Serratia marcescens strain Neni-1. Additionally, it identified three significant parameters that contribute to optimized decolorization of Congo Red: pH, incubation time, and the concentration of Congo Red. Various diagnostic plots were used to analyze the important contributing factors or parameters, including ANOVA, Pareto's chart, and perturbations plot. The two-level factorial conclusion was supported by diagnostic plots such as half-normal, residual vs runs, Cook's distance, Box-Cox, leverage vs runs, DFBETAS, and DFFITS. Consistent with trends in the published literature, this study found that the majority of Congo Red-degrading microorganisms thrive in nearly neutral environments. In future works, RSM can be used to further optimize the parameters that contributed to the decolorization of this bacterium on Congo Red.

Effectiveness of potassium humate and endophytic bacteria from Serratia marcescens strain NPKC3_2_21 in increasing root weight of paddy cultivation in acidic soil

Abstract. Sutio G, Iskandar, Indriyati LT, Djajakirana G. 2023. Effectiveness of potassium humate and endophytic bacteria from Serratia marcescens strain NPKC3_2_21 in increasing root weight of paddy cultivation in acidic soil. Biodiversitas 24: 6316-6322. Phosphorus (P) deficiency is a significant factor limiting rice agricultural production in acidic soil. The availability of P in acidic soil is generally insufficient because a substantial portion of P is absorbed by Al³? and Fe²?, rendering it inaccessible to plants. This P deficiency in acidic soil hampers proper root growth. However, this limitation can be overcome by the application of potassium humate and endophytic bacteria. The objective of this study was to investigate the effects of phosphate fertilizer with and without potassium humate and/or endophytic bacteria on root growth in acidic fields. The research involved two treatment factors. The first factor comprised four levels of ex-madura phosphate rock fertilizer: 100% (1), 75% (2), 50% (3), 25% (4), and no application of phosphate rock fertilizer (5) and the second factor included potassium humate (A), endophytic bacteria from Serratia marcescens strain NPKC3_2_21 (B), a combination of potassium humate and S. marcescens endophytic bacteria (C), and the absence of both potassium humate and S. marcescens endophytic bacteria (D). The results revealed a positive interaction between phosphate fertilizer, the combination of potassium humate, and S. marcescens endophytic bacteria. Therefore, utilizing endophytic bacteria from S. marcescens and potassium humate could be an effective strategy for increasing root biomass in rice plants grown in acidic soil with a deficiency in available P.

Evaluation of microbial biocontrol agents for Ganoderma boninense management in oil palm nurseries

Importance of the workMicroorganisms play a pivotal role in the growth and development of plants, making their interaction a promising avenue for managing plant diseases, including those affecting oil palm cultivation. ObjectivesIn this study, endophytic microbes such as actinomycetes, bacteria, and fungi were isolated from healthy oil palm tissue in susceptible areas to serve as stock isolates. These isolates underwent in vitro evaluation to determine their efficacy in controlling Ganoderma boninense and to identify bioactive metabolites. Additionally, in planta tests were conducted using bioformulations. Materials & MethodsA dual culture assay was utilized to assess the inhibitory effects of three different stock isolates on G. boninense. To detect bioactive metabolites responsible for the inhibition, particularly phenazine and syringic acid, a series of procedures involving fermentation, extraction, and LC-MS analysis were employed. Furthermore, the efficacy of bioformulations employing various carriers and consisting of either microbial consortia was meticulously evaluated in a nursery setting. The main focus of this evaluation was to determine their capacity to effectively curb disease onset and maintain the vegetative growth of oil palm during the progression of G. boninense. ResultsSeveral strains of indigenous bacteria (Pseudomonas aeruginosa strain JQ-41, Serratia marcescens strain S16, Stenotrophomonas rhizophila strain CASMBAUDAL2), an actinobacterium (Streptomyces sp.), and a fungus (Trichoderma sp.) exhibited significant growth inhibition against G. boninense. Based on the results obtained from the LC-MS analysis of the ethyl acetate extract, it was revealed that the extract contains 2 compounds known as antifungal agents, namely phenazine and syringic acid. The most effective approach to mitigate infection involved the preventive application of bioformulations containing mixed bacterial isolates or microbial consortia. After 12 months of observation, these bioformulations demonstrated efficacy comparable to that of Marfu-P, a commercially available biofungicide for oil palm seedlings. Main findingThe study establishes the effectiveness of endophytic bioformulations as a viable strategy to manage the onset of G. boninense disease, highlighting the potential of microorganisms as an alternative solution for controlling basal stem rot in the nursery.

A study on bioactive potential of Serratia marcescens from marine environment

Marine microorganisms are diverse and excessively incompatible from the terrestrial counterparts, making them a great promising tool for biotechnological applications in the area of agriculture, health, and environment. This research study mainly focused on a novel strain Serratia marcescens MBBTBC9 from marine environment. The characterization of Serratia marcescens MBBTBC9 revealed its tolerance profile against various abiotic stresses like temperature in the range of 4–50 °C, 0.5 %- 7 % NaCl concentration and pH between 7 and –13 and heavy metals with a maximum resistance level of 500 ppm against lead and copper. Atomic absorption spectroscopy elucidated the ability of S. marcescens in the removal of heavy metals. Plant growth promoting ability of S. marcescens MBBTBC9 assessed using Vigna unguiculata, the common crop cultivated in different states of India, it significantly enhanced seed germination, seedling vigour, seedling emergence and growth enhancement in both plate and pot assay. Thus, this study discloses the biological potential of S. marcescens MBBTBC9 to be a promising stress tolerant plant growth promoting marine bacterium.

Assessing the biodegradation efficiency and underlying molecular pathway of strain AEPI 0–0: A newly isolated tetracycline-degrading Serratia marcescens

With the development of aquaculture and animal husbandry, the use of tetracycline antibiotics (TCs) has increased, thereby leading to negative impacts on naturally-occurring microbial communities. Microbial degradation is an effective and environmental friendly method to degrade TCs, but so far, very few cultured strains are suitable for this purpose. In this study, a bacterial strain, AEPI 0–0, with the potential to degrade TCs was isolated, with phylogenetic analysis subsequently classifying it as Serratia marcescens. The single factors that affected the strain’s degradation efficiency on TC-HCl were then studied using an orthogonal experimental design. The results showed that the biodegradation efficiency could reach about 85% on the 4th day, with the process following the degradation kinetic equation. Subsequently, RNA-seq was used and the differentially expressed genes（DEGs）were annotated and analyzed. The results showed that more genes were enriched in biological processes such as amino acid metabolism, carbohydrate metabolism, and cell membrane transport metabolism pathway. In addition, TetR family transcription factors may play an important role in the physiological process of AEPI 0–0 tolerance and degradation of tetracycline. In conclusion, a Serratia marcescens strain with high potential for TCs degradation was obtained, with the conditions for maximum degradation efficiency subsequently optimized, changes in the metabolic pathways were also preliminarily discussed. This strain could potentially be applied for the bioremediation of soil and water contaminated by TCs antibiotics. At the same time, this study also provides strains as well as theoretical support for microbial-based remediation of the environment.

Rhs NADase effectors and their immunity proteins are exchangeable mediators of inter-bacterial competition in Serratia

Many bacterial species use Type VI secretion systems (T6SSs) to deliver anti-bacterial effector proteins into neighbouring bacterial cells, representing an important mechanism of inter-bacterial competition. Specific immunity proteins protect bacteria from the toxic action of their own effectors, whilst orphan immunity proteins without a cognate effector may provide protection against incoming effectors from non-self competitors. T6SS-dependent Rhs effectors contain a variable C-terminal toxin domain (CT), with the cognate immunity protein encoded immediately downstream of the effector. Here, we demonstrate that Rhs1 effectors from two strains of Serratia marcescens, the model strain Db10 and clinical isolate SJC1036, possess distinct CTs which both display NAD(P)+ glycohydrolase activity but belong to different subgroups of NADase from each other and other T6SS-associated NADases. Comparative structural analysis identifies conserved functions required for NADase activity and reveals that unrelated NADase immunity proteins utilise a common mechanism of effector inhibition. By replicating a natural recombination event, we show successful functional exchange of CTs and demonstrate that Db10 encodes an orphan immunity protein which provides protection against T6SS-delivered SJC1036 NADase. Our findings highlight the flexible use of Rhs effectors and orphan immunity proteins during inter-strain competition and the repeated adoption of NADase toxins as weapons against bacterial cells.

Molecular Characterization of Serratia marcescens Strain Isolated from Yellow Mealworms, Tenebrio molitor, in The Netherlands.

Insect culture has developed rapidly worldwide; it faces important security and safety control issues, including animal infections and disease development. In the Netherlands, in 2021, a ~30% mortality of mealworms, Tenebrio molitor, occurred at one farm, where over-humid sites in the substrate were observed. Bacterial cultures from both the external and internal partsof fry and larger mealworms were identified by MALDI-TOF to predominantly Serratia marcescens, Staphylococcus xylosus and Staphylococus saprofyticus. Due to the important role of S. marcescens as a potential zoonotic bacterium, we performed a molecular characterization of the isolated strain. Genomic analysis showed a multidrug-resistant S. marcescens isolate carrying a tet (41), aac (6')-Ic, and blaSST-1 chromosomal class C beta-lactamase-resistantgenes, all located on the chromosome. Additionally, several virulence genes were identified. The phylogenetic tree revealed that the S. marcescens strain from this study was similar to other S. marcescens strains from different ecological niches. Although the entomopathogenic activity was not confirmed, this case demonstrates that T. molitor can act as a reservoir and as an alternative path for exposing clinically important antibiotic-resistant bacteria that can affect animals and humans. It underlines the need to keep management factors optimal, before insects and their products enter the feed and food chain.

Assessment of enhanced p-cresol biodegradation by encapsulating pre-immobilised Serratia marcescens strain HL 1 on tea waste biochar into polyvinyl alcohol/sodium alginate matrix

In this study, the potential microorganism was isolated from activated sludge to degrade the p-cresol from wastewater. The isolated species (i.e., Serratia marcescens strain ΗL 1) was identified using a 16 S rRNA gene sequencing technique. Microorganism was immobilized into 1% (w/v) tea waste biochar and encapsulated into polyvinyl alcohol (PVA)/sodium alginate (SA) matrix to save the pure species from contaminant and able to sustain under high loading concentration. The maximum biodegradation efficiency was found to be 86.1 ± 2.0% of p-cresol by using PVA/SA (pre-immobilized (PI) (1%) biochar into PVA/SA) matrix which is much higher than the free cell (42.4 ± 0.7%) and immobilized system (73.8 ± 1.0). The % biodegradation of p-cresol was reduced from 86.1 ± 2.0–80.2 ± 1.4% after the fourth cycle. The matrix's surface morphology and the functional group were analysed by SEМ and FTIR, respectively. Monod and Andrew-Haldane model was used to identify biokinetic parameters. This research work revealed that an innovative PI(1%)biochar@PVA/SA matrix would be useful for the bioremediation of p-cresol. The main metabolic by-product obtained were 4-hydroxybenzoylalcohal (m/z = 124), 4-hydroxybenzoic acid (m/z = 138), maleic acid (m/z = 116) and acetaldehyde (m/z = 29)

ENDOPHYTIC TESTING OF Serratia marcescens strain NPKC3_2_21 AGAINST INPARA 3 RICE VARIETY

Pest management is a crucial concern, especially when dealing with insect pests that can cause extensive damage to agricultural crops and the economy. One such pest is the rice stem borer (Scirpophaga innotata), which infests rice stems and poses a significant threat. To combat these pests, various microbial agents have been developed for effective pest control. Among these, the endophytic microbe in biological plant protection plays a key role in the program of sustainable pest management. An endophytic bacterium, Serratia marcescens strain NPKC3_2_21, has been identified as a key player in sustainable pest management, particularly in rice crops. In this study, we aimed to investigate the endophytic characteristics of S. marcescens strain NPKC3_2_21 in the swamp rice plant of the Inpara 3 variety of swamp rice plants. To establish its roles. Marcescens as an endophytic bacterium in rice plants, specifically the Inpara 3 variety, we conducted tests by inoculating bacteria on the plant tissue of rice plants that have been sterilized rice plant tissues with the bacteria. We assessed the presence of S. marcescens strain NPKC3_2_21 in plant tissues by applying isolates to the surface of rock wool, which supported the growth of wet rice plants aged ten or over ten days or older after planting. Samples were collected from the underside of the stem, the bottom of the leaves, and the roots on days 2, 7, and 14 after the application of isolates to the rock wool. The samples were then washed in 70% alcohol and 4% chlorox for 30 seconds and subsequently isolated on Luria Bertani (LB) agar media. Furthermore, we conducted tests to determine the ligninolytic, cellulolytic, and proteolytic activities of S. marcescens, which helped elucidate its endophytic ability. Based on the result, the endophytic capabilities. Based on the results, we found that S. marcescens strain NPKC3_2_21 exhibited endophytic characteristics solely in the stem tissue of the Inpara 3 rice variety. However, we did not observe its presence in the root and leaf tissues.

Intensive care unit sinks are persistently colonized with multidrug resistant bacteria and mobilizable, resistance-conferring plasmids.

Contamination of hospital sinks with microbial pathogens presents a serious potential threat to patients, but our understanding of sink colonization dynamics is largely based on infection outbreaks. Here, we investigate the colonization patterns of multidrug-resistant organisms (MDROs) in intensive care unit sinks and water from two hospitals in the USA and Pakistan collected over 27 months of prospective sampling. Using culture-based methods, we recovered 822 bacterial isolates representing 104 unique species and genomospecies. Genomic analyses revealed long-term colonization by Pseudomonas spp. and Serratia marcescens strains across multiple rooms. Nanopore sequencing uncovered examples of long-term persistence of resistance-conferring plasmids in unrelated hosts. These data indicate that antibiotic resistance (AR) in Pseudomonas spp. is maintained both by strain colonization and horizontal gene transfer (HGT), while HGT maintains AR within Acinetobacter spp. and Enterobacterales, independent of colonization. These results emphasize the importance of proactive, genomic-focused surveillance of built environments to mitigate MDRO spread. IMPORTANCE Hospital sinks are frequently linked to outbreaks of antibiotic-resistant bacteria. Here, we used whole-genome sequencing to track the long-term colonization patterns in intensive care unit (ICU) sinks and water from two hospitals in the USA and Pakistan collected over 27 months of prospective sampling. We analyzed 822 bacterial genomes, representing over 100 different species. We identified long-term contamination by opportunistic pathogens, as well as transient appearance of other common pathogens. We found that bacteria recovered from the ICU had more antibiotic resistance genes (ARGs) in their genomes compared to matched community spaces. We also found that many of these ARGs are harbored on mobilizable plasmids, which were found shared in the genomes of unrelated bacteria. Overall, this study provides an in-depth view of contamination patterns for common nosocomial pathogens and identifies specific targets for surveillance.

Clonal dissemination of highly virulent Serratia marcescens strains producing KPC-2 in food-producing animals

Serratia marcescens is a Gram-negative bacterium presenting intrinsic resistance to polymyxins that has emerged as an important human pathogen. Although previous studies reported the occurrence of multidrug-resistance (MDR) S. marcescens isolates in the nosocomial settings, herein, we described isolates of this extensively drug-resistant (XDR) species recovered from stool samples of food-producing animals in the Brazilian Amazon region. Three carbapenem-resistant S. marcescens strains were recovered from stool samples of poultry and cattle. Genetic similarity analysis showed that these strains belonged to the same clone. Whole-genome sequencing of a representative strain (SMA412) revealed a resistome composed of genes encoding resistance to β-lactams [blaKPC-2, blaSRT-2], aminoglycosides [aac(6′)-Ib3, aac(6′)-Ic, aph(3′)-VIa], quinolones [aac(6′)-Ib-cr], sulfonamides [sul2], and tetracyclines [tet(41)]. In addition, the analysis of the virulome demonstrated the presence of important genes involved in the pathogenicity of this species (lipBCD, pigP, flhC, flhD, phlA, shlA, and shlB). Our data demonstrate that food-animal production can act as reservoirs for MDR and virulent strains of S. marcescens.

Coagulant aids showed negligible effect on the flocculation capacity of the fermentation broth produced by a newly isolated strain of Serratia marcescens, XN-6

The flocculation process usually requires the addition of coagulants containing metal ions, which may lead to secondary pollution. In this study, the bio-flocculant produced by Serratia marcescens XN-6 did not depend on the coagulant. The optimal conditions for strain XN-6 to produce its fermentation broth for flocculation were as follows: 2.5% sucrose, 1% ammonium sulfate, 25 °C, pH 7.0, and 5% inoculum size, for which the highest flocculation efficiency of the fermentation broth achieved was 80.08%. The highest flocculation efficiency of the bacterial suspension that could be obtained was only 75.11% after supplementing the broth with 1% CaCl2. These results indicate that the flocculation activity of the fermentation broth was more efficient than that of bacterial suspension, even if CaCl2 was supplemented as a coagulant aid. This study may provide a novel type of bio-flocculant with coagulant aid-independence to be used for breaking down chemical pollution in the environment.