Enterobacter Cloacae Strain Research Articles

Cation exchange resin coupled with bacterial pretreatment to promote waste activated sludge reduction: Performance and mechanism

Due to the rapid advancement of industrialization and urbanization, there has been a significant rise in the generation of industrial wastewater and domestic wastewater, which results in the rapid increase of waste activated sludge (WAS). However, the complex structure and slow hydrolysis of sludge limit aerobic digestion of WAS. This study evaluated the effect of lysozyme-secreting strain Proteus mirabilis sp. SJ25 and the new isolation of surfactant-secreting strain Enterobacter cloacae sp. WH11 on the promotion of sludge hydrolysis, and introduced cation exchange resin (CER) to enhance the promotion effect. The reduction efficiencies of suspended solids (SS) and volatile suspended solids (VSS) enhanced by 25.0 and 24.9 %, respectively, and the soluble chemical oxygen demand (SCOD) release was increased by 2370.27 mg/L when the inoculum of strain SJ25 and strain WH11 were 3 % and 6 %, and the dosage of CER was 2.0 g/g SS against the control. The fluorescence region integral (FRI) results showed a significant quantity of dissolved organic matter (DOM) was let out, and the biodegradability of the sludge was improved. The alterations in several physicochemical characteristics of the sludge also suggested that the extracellular polymeric substances (EPS) were disrupted and an enormous quantity of sludge cells were lysed. In addition, functional gene prediction from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database indicated that CER coupled with bacterial pretreatment enhanced microbial metabolic capacity. This work suggests a novel pathway for the development of novel pretreatment methods to promote sludge hydrolysis.

In-situ chemobiocatalytic conversion of glucose into 2,5-bis(hydroxymethyl)furan by AlCl3/Enterobacter cloacae in biocompatible DMSO-water solvent

In-situ chemobiocatalytic production of 2,5-bis(hydroxymethyl)furan (BHMF) from glucose is extremely desirable but challenging owing to the incompatibility issues between two worlds of catalysts. In this study, a robust strain Enterobacter cloacae HA188, which is tolerant to 20% (v/v) DMSO, was used in the direct conversion of glucose into BHMF. The dehydration of glucose into 5-hydroxymethylfurfural (HMF) was catalyzed by AlCl3 in DMSO at 130 °C for 0.5 h, then water and E. cloacae cells were added and the bio-reduction of HMF was directly performed in 20% (v/v) DMSO at 30 °C for 6 h. Under the optimized conditions, 1000 mM glucose was transformed into HMF at 51.1% yield, which was further converted into BHMF with an overall yield of 47.2%. The BHMF yield was further improved when fructose or sucrose were utilized. This work provided a sustainable way for the production of value-added BHMF from inexpensive glucose under benign conditions.

Characterization and genomic analysis of the lytic bacteriophage vB_EclM_HK6 as a potential approach to biocontrol the spread of Enterobacter cloacae contaminating food

BackgroundIncreased prevalence of Enterobacter cloacae within food products underscores food as an underexplored reservoir for antibiotic resistance, thus requiring particular intervention. Bacteriophages have been explored as a promising approach for controlling bacterial growth in different matrices. Moreover, their specific interaction and self-replication, put them apart from traditional methods for controlling bacteria in different matrices.MethodsSixteen Enterobacter cloacae strains were recovered from raw chicken. These strains were used to isolate bacteriophages using enrichment protocol. The broad-spectrum bacteriophage was evaluated in terms of thermal, pH, shearing stress and storge. Moreover, its infection kinetics, in vitro antibacterial activity, cytotoxicity were also assessed. Genomic sequencing was performed to exclude any potential virulence or resistance genes. Finally, the capability of the isolated phages to control bacterial growth in different chicken samples was assessed alone and in combination with sodium nitrite.ResultsThe lytic bacteriophage vB_EclM_HK6 was isolated and showed the broadest spectrum being able to infect 8/16 E. cloacae strains with a lytic activity against its host strain, E. cloacae EC21, as low as MOI of 10–6. The phage displays a latent period of 10 min and burst size of 115 ± 44 and resistance frequency of 5.7 × 10–4 ± 3.0 × 10–4. Stability assessment revealed a thermal tolerance up to 60 ˚C, wide range pH stability (3–10) and the ability to withstand shearing stress up to 250 rpm. HK6 shows no cytotoxicity against oral epithelial cells up to 1012 PFU/ml. Genomic analysis revealed a Strabovirus with total size of 177,845 bp that is free from known resistance and virulence genes. Finally, HK6 pretreatment of raw chicken, chicken nuggets and ready-made cheese salad shows a reduced bacterial count up to 4.6, 2.96 and 2.81 log-units, respectively. Moreover, combing HK6 with sodium nitrite further improved the antibacterial activity in both raw chicken and chicken nuggets without significant enhancement in case of cheese salad.ConclusionEnterobacter bacteriophage vB_EclM_HK6 presents a safe and effective approach for controlling E. cloacae contaminating stored chicken food samples. Moreover, they could be combined with a reduced concentrations of sodium nitrite to improve the killing capacity.

Study of the mechanisms of heteroresistance to colistin in a strain of Enterobacter cloacae by random mutagenesis

Enterobacter cloacae complex belong to a group for which colistin resistance is not well documented, due to their frequent heteroresistance. Previous studies have examined the role of the two-component systems PhoP-PhoQ and its negative regulator mgrB or the arnBCADTEF operon. We investigated the molecular basis of colistin heteroresistance using genome analysis and random mutagenesis in a strain of Enterobacter cloacae and identified the arnA gene as responsible for colistin resistance.

Investigation of in vitro susceptibility and resistance mechanisms to amikacin among diverse carbapenemase-producing Enterobacteriaceae

ObjectiveThis study aims to assess the in vitro drug susceptibility of various Carbapenemase-Producing Enterobacteriaceae (CPE) genotypes and elucidate the underlying mechanisms of amikacin resistance.MethodsA total of 72 unique CPE strains were collected from the Second Hospital of Jiaxing between 2019 and 2022, including 51 strains of Klebsiella pneumoniae, 11 strains of Escherichia coli, 6 strains of Enterobacter cloacae, 2 strains of Klebsiella aerogenes, 1 strain of Citrobacter freundii, and 1strain of Citrobacter werkmanii. Among these strains, 24 carried blaKPC gene, 20 carried blaNDM gene, 23 carried blaOXA−48−like gene, and 5 carried both blaKPC and blaNDM. We measured the in vitro activity of amikacin and other common antibiotics. Strains carrying blaOXA−48-like gene were selected for whole genome sequencing (WGS) via next-generation sequencing to identify genes related to antimicrobial resistance (AMR) and virulence factor (VF).ResultsOut of the 72 CPE strains tested, 41.7% exhibited resistance to amikacin. The drug resistance rates for K. pneumoniae, E. coli, and Enterobacter spp. were 51.0%, 27.3%, and 10.0%, respectively. The majority of the CPE strains (> 90%) displayed resistance to cephalosporins and carbapenems, while most of them were sensitive to polymyxin B and tigecycline (97.2% and 94.4%). The amikacin resistance rate was 100% for strains carrying blaOXA−48, 20.8% for those with blaKPC, 5.0% for those with blaNDM, and 20.0% for those with both blaKPC and blaNDM. These differences were statistically significant (P < 0.05). Through sequencing, we detected aminoglycoside resistance genes rmtF and aac(6’)-Ib, VF genes iucABCD and rmpA2 in OXA-48-producing multidrug resistance and highly virulent strains. These genes were located on a IncFIB- and IncHI1B-type plasmid, respectively. Both plasmids were highly homologous to the plasmid from OXA-232 strains in Zhejiang province and Shanghai province. Integration of these resistance genes into the IncFIB plasmid, facilitated by the IS6 and/or Tn3 transposons, resulted in OXA232-producing K. pneumoniae with amikacin resistance.ConclusionThis study identified significant amikacin resistance in CPE strains, particularly in those carrying the blaOXA−48 gene. Resistance genes rmtF and aac(6’)-Ib were identified on plasmids. These results highlight the need for careful monitoring of amikacin resistance.

Distribution characteristics of integrons and correlation analysis of antibiotic resistance in urine isolated Enterobacter cloacae.

This study aims to understand the distribution of integrons among Enterobacter cloacae isolated from clinical urine specimens in our hospital, as well as the molecular characteristics of the variable region resistance gene cassette of integron-positive strains and its relationship with drug resistance. We collected a total of 80 strains of Enterobacter cloacae isolated from urine specimens of hospitalized patients in our hospital between August 2019 and July 2023, and conducted drug sensitivity testing on them. Polymerase Chain Reaction (PCR) technology was employed to screen these strains for Class 1, 2, and 3 integrons. Following this, the promoter and variable regions of integron-positive strains were amplified and sequenced. Additionally, Enterobacterial Repetitive Intergenic Consensus PCR (ERIC-PCR) was utilized for homology analysis of integron-positive strains. Among the 80 clinical strains, Class 1 integrons were detected in 31 (38.8%) strains, and the following resistance gene cassettes were identified: aadA2, aadA1, aadB, aac(6'), and catB8. Three types of variable region promoters were observed: PcS (4 strains), PcW (7 strains), and PcH1 (17 strains), with consistently inactive downstream P2 promoters. Additionally, Class 2 integrons were detected in 5 (6.3%) strains, carrying the variable region resistance gene cassette dfrA1-sat2-aadA1. The promoters for Class 2 integrons were uniformly of the Pc2D-Pc2A-Pc2B-Pc2C type. No Class 3 integrons were detected. The strains containing integrons showed significantly higher resistance rates to ciprofloxacin, compound sulfamethoxazole, levofloxacin, gentamicin, amikacin, and tobramycin compared to those without integrons (P<0.05). 35 strains of Enterobacter cloacae carrying integrons are primarily classified into three genotypes: A, B, and C. These genotypes are mainly distributed in the urology department and Intensive Care Unit (ICU). The distribution of variable region gene boxes and promoter types is relatively concentrated in the same genotype. Our study confirmed that Enterobacter cloacae isolated from urine samples predominantly carries Class 1 integrons with an extended array of antibiotic-resistant genes. For future research, it is recommended to explore additional resistance mechanisms and evaluate the effectiveness of new therapeutic strategies. Clinicians should be vigilant about the possibility of clonal dissemination and implement enhanced infection control measures in hospital settings.

Evaluation of the antibacterial effect of (R)-(+)-Limonene against Enterococcus faecalis and Enterobacter cloacae strains isolated from food

The aim of this study was to evaluate the potential antibacterial and anti-adherent activities of the monoterpene (R)-(+)-limonene, as well as its synergistic potential with synthetic antimicrobials against strains of Enterococcus faecalis and Enterobacter cloacae. The antibacterial properties of (R)-(+)-limonene were assessed using the broth microdilution technique to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Additionally, the infusion disc method was employed to explore the association of the compound with antimicrobials, and the test tube method was used to determine the minimum inhibitory concentration of adherence (MICA). It was observed that the MIC for (R)-(+)-limonene was 1000 μg mL-1 for five of the six E. faecalis strains tested, while for E. cloacae, the MIC exceeded 1000 μg mL-1 for all strains tested. Identical values were recorded for the MBC in E. faecalis. In terms of its combination with synthetic antimicrobials, (R)-(+)-limonene demonstrated a synergistic effect with gentamicin and ciprofloxacin for most strains. Regarding the MICA, both (R)-(+)-limonene and 0.12% chlorhexidine digluconate failed to inhibit biofilm formation at the tested concentrations. Given the need for new therapeutic alternatives for treating bacterial infections, this study revealed that the tested monoterpene exhibited moderate bactericidal effects against E. faecalis strains and no antibacterial effect against E. cloacae strains. However, when combined with various classes of antimicrobials, (R)-(+)-limonene showed synergistic effects with gentamicin and ciprofloxacin for most strains. This suggests that (R)-(+)-limonene holds promise for enhancing the treatment of bacterial infections and could support conventional therapies. Nonetheless, further in vitro, ex vivo, and in vivo studies are necessary to confirm and elucidate its efficacy and mechanisms.

Influences of Enterobacter Cloacae Strain Fg 5-2 and Its Vermicompost and Nitrogen Fertilizer Usage Efficiency on Groundnut Yield

Influences of Enterobacter Cloacae Strain Fg 5-2 and Its Vermicompost and Nitrogen Fertilizer Usage Efficiency on Groundnut Yield

Enterobacter cloacae-mediated polymer biodegradation: in-silico analysis predicts broad spectrum degradation potential by Alkane monooxygenase.

Plastic pollution poses a significant environmental challenge. In this study, the strain Enterobacter cloacae O5-E, a bacterium displaying polyethylene-degrading capabilities was isolated. Over a span of 30days, analytical techniques including x-ray diffractometry, scanning electron microscopy, optical profilometry, hardness testing and mass spectrometric analysis were employed to examine alterations in the polymer. Results revealed an 11.48% reduction in crystallinity, a 50% decrease in hardness, and a substantial 25-fold increase in surface roughness resulting from the pits and cracks introduced in the polymer by the isolate. Additionally, the presence of degradational by-products revealed via gas chromatography ascertains the steady progression of degradation. Further, recognizing the pivotal role of alkane monooxygenase in plastic degradation, the study expanded to detect this enzyme in the isolate molecularly. Molecular docking studies were conducted to assess the enzyme's affinity with various polymers, demonstrating notable binding capability with most polymers, especially with polyurethane (-5.47kcal/mol). These findings highlight the biodegradation potential of Enterobacter cloacae O5-E and the crucial involvement of alkane monooxygenase in the initial steps of the degradation process, offering a promising avenue to address the global plastic pollution crisis.

Mining a bioremediation genetic toolbox in the novel environmental bacteria Enterobacter cloacae strain amazonensis

Mining a bioremediation genetic toolbox in the novel environmental bacteria Enterobacter cloacae strain amazonensis

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.

Assessment of the Sensitivity of Foodborne Cronobacter spp. Strains and Other Enterobacteria to Temperature Stresses and Chlorine-Containing Biocides.

We examined the effects of elevated temperatures and biocides on survivability of food isolates of Cronobacter spp. (C. sakazakii) and concomitant enterobacteriaceae obtained in microbiological control of infant nutrition products. Increased resistance of certain strains of Cronobacter, Enterobacter cloacae, and Pantoea spp. to thermal processing was revealed. Salmonella, Pantoea, and Cronobacter bacteria were least sensitive to antimicrobial action of chlorine-containing agents. The above properties varied in the strains of the same species. Specifically, only two of three examined isolates of Cronobacter spp. demonstrated lower sensitivity to heat in comparison with the enterobacterial test-cultures of other species.

Removal of residual organic pollutants from pulp paper industry wastewater using bacterial strains Acinetobacter baumannii (OK582199) PC4 and Bacillus cereus (OK582201) PC10 via biostimulation and bioaugmentation process

This study examines how native bacteria, combined with two specific aerobic strains (Acinetobacter baumannii PC4 and Bacillus cereus PC10), contribute to the detoxification of pulp and paper industrial wastewater (PPIW) through biostimulation and bioaugmentation processes. The growth of two native bacteria were stimulated in pulp paper industry wastewater by the addition of carbon (1% glucose) and nitrogen (0.5% peptone w/v). After the growth of these native bacteria in biostimulation process showed significant reduction in various physico-chemical parameters i.e. lignin (53%), color (46%), COD (76%), and BOD (86%). Similarly, reductions in various heavy metals were also observed, such as Fe (73%), Zn (36%), Cr (41%), Cu (22%), and Ni (65%). The growing native bacterial co-culture were identified as Enterobacter cloacae strain PC7 (OQ672613) and Bacillus sp. strain PCB (OK614116). However, the addition of Acinetobacter baumannii (OK582199) PC4 and Bacillus cereus (OK582201) PC10 enhanced the reduction of various physico-chemical parameters in range of 10–––28%. Consequently, the UV–Vis absorption peak showed reduction due to the decolorization of wastewater and degradation of various pollutants. Moreover, GC–MS analysis indicated that most of the compounds detected in the control were diminished after bacterial treatment. However, compounds such as Pentadecane, 2-Methyl, Silane (dodecylosy) trimethyl, Octadecanoic acid, trimethylsilyl ester, and Docasane were noted as recalcitrant. Additionally, new metabolic products such as 1-ethyl-5,6-dimethoxy-2,3-dihydroindole, Trimethylsily ether of glycerol, and 1-(Trimethylsilylmethyl1) dimethylsilyloxy tetradecane were detected. Due to degradation of various pollutants toxicity reductions were found up to 76% during a comparative evaluation between control and bacterial treated wastewater using the Phaseolus mungo L. seed germination test. Hence, it was concluded that the biostimulation and bioaugmentation process would be an effective technique for degrading residual organic pollutants from pulp and paper industrial wastewater (PPIW) for safe disposal.

The Abundance of Plasmid-Mediated Quinolone Resistance Genes in Enterobacter cloacae Strains Isolated from Clinical Specimens in Kermanshah, Iran.

Enterobacter cloacae (E. cloacae) is one of the most common Enterobacteriaceae causing nosocomial infections. Plasmid-mediated quinolone resistance (PMQR) determinants have been considered recently. This study evaluated the abundance of PMQR genes in strains of E. cloacae obtained from clinical samples in Kermanshah, Iran. In this descriptive cross-sectional study, after collecting 113 isolates of E. cloacae, their identity was confirmed using specific biochemical tests. After determining their drug resistance patterns using disc diffusion, the phenotypic frequency of extended-spectrum beta-lactamase (ESBL)-producing isolates was measured by the double-disk synergy test (DDST) method. The isolates were examined for the presence of qnrA, qnrB, qnrS, and aac(6')-Ib-cr genes by the polymerase chain reaction (PCR) assay. The antibiotic resistance rate of E. cloacae isolates varied from 9.7% to 60.2%; among them, 78% were multidrug-resistant (MDR). The highest quinolone resistance was observed in ESBL-producing strains of E. cloacae. The frequency of positive isolates for PMQR and ESBL was 79.6% and 57.5%, respectively. The genes aac(6')-ib-cr (70.8%) and qnrB (38.1%) had the highest frequency among other genes. The number of isolates simultaneously carrying 2 and 3 genes was 64 and 5 isolates, respectively. The obtained results indicate a high degree of quinolone resistance among ESBL-producing E. cloacae strains. Nevertheless, there was a significant relationship between the PMQR gene and ESBL-positive isolates. Therefore, special attention should be paid to molecular epidemiological studies on antibiotic resistance to quinolones and beta-lactamases in these strains.

Chromium-stress alleviation study using plant growth promoting rhizobacteria for maize ( Zea mays L.)

Heavy metal contamination is one of the major environmental threats due to industrialization and urbanization. Among various heavy metals, chromium is of recent concern because it is considered the most hazardous metal pollutant in the environment. Its toxicity alters the process of germination and various other growth parameters ultimately affecting its yield. While maize (Zea mays L.) is one of the most widely cultivated cereal crop being used for fodder, feed and food purposes. It is multipurpose cereal crop and is also used as raw material for different industries. Hence, it is mandatory to come up with effective eco-friendly technique to remediate chromium (Cr) to protect the environment from its toxic impacts. During current research, plant microbe interaction was carried out with Cr resistant strains of Bacillus cereus (3a), Pseudomonas aeruginosa (DS4), Bacillus nitratireducens (TP8), Enterobacter cloacae (A9G) and Pseudomonas sp. (B3) that were selected to observe their beneficial impact on corn (Zea mays L.) growth in presence of Cr stress (150 &amp; 300 µg/mL). Results have indicated that growth and biochemical parameters were enhanced due to bacterial inoculation. In comparison to control, maximum increment in shoot length, number of leaves, root length and fresh weight of inoculated plants was noted up to 46, 115, 76, and 42% respectively. Maximum increment in protein and chlorophyll content of inoculated plants was noted up to 304 and 71% respectively as compared to control. The present study suggests the use of above-mentioned highly chromium resistant bacterial strains to remediate chromium contaminated sites and to improve agricultural production.

Enhancing iron bioavailability in lentil grains circumventing the phytate barrier

The study aimed at examining the effect of Iron (Fe) management strategies on the redistribution of Fe fractions in soil and on the Fe bioavailability and phytic acid (PA) content in lentil grains. A pot experiment was conducted in Completely Randomized Design with 8 treatments replicated thrice. The treatments were Control (no fertilizer); Recommended dose of fertilizers (RDF) i.e. 20:40 (N: P2O5); RDF + Fe (basal application @10 kg/ha); RDF + Fe (foliar@ 1% (w/v) solution); RDF + Fe (basal + foliar); RDF + FeSB (biopriming with Fe solubilizing bacteria (Enterobacter cloacae strain BAU3) @ 5 mL/kg seed (1 x109 cfu mL−1)); RDF + Fe (seed nutripriming with 1% (w/v) solution); and RDF + (biopriming + nutripriming). Fe source for the treatments was Fe-EDDHA chelate. Higher Fe release from these fractions was observed under biopriming + nutripriming with water soluble Fe of 21.09 and 20.82 mg kg−1, respectively for the biopriming + nutripriming and sole biopriming treatments; and organically bound Fe of 230.95 and 211.36 mg kg−1 for the same treatments. These fractions contributed toward higher Fe uptake which was highest under biopriming + nutripriming. Values were statistically significant for biopriming and nutripriming and basal + foliar treatment. Lowest PA values in lentil grains as well as PA/Fe ratio were estimated under basal + foliar and biopriming + nutripriming treatments. Combined basal and foliar application of Fe esp. in chelated form and use of seed priming strategies have immense potential in enhancing the Fe bioavailability in grains from soil, seed or foliage.

In vitro activity of human defensins HNP-1 and hBD-3 against multidrug-resistant ESKAPE Gram-negatives of clinical origin and selected peptidoglycan recycling-defective mutants.

In the current scenario of critical need for new antimicrobials against multidrug-resistant bacteria, all options must be considered, including classic ideas such as the use of purified immune compounds. However, information regarding the activity of certain human defensins against ESKAPE Gram-negatives was incomplete. This is the first study comparatively assessing the in vitro activity of two membrane-permeabilizing/peptidoglycan construction-blocking defensins (HNP-1 and hBD-3) against relevant clinical collections of ESKAPE Gram-negatives, alone or in combination with permeabilizers, additional peptidoglycan-targeting attacks, or the blockade of its recycling. Our data suggest that hBD-3 has a notable bactericidal activity against multidrug-resistant Acinetobacter baumannii and Enterobacter cloacae strains that should be considered as potential adjuvant option. Our results suggest for the first time an increased resistance of Pseudomonas aeruginosa strains from chronic infection compared to acute origin ones, and provide new clues about the predominant mode of action of hBD-3 against Gram-negatives (permeabilization rather than peptidoglycan-targeting).

Mechanisms involved in plant growth promotion by Enterobacter cloacae DJ under salinity-alkalinity stress

BackgroundPlant-promoting bacteria are safer alternatives to pesticides and fertilizers, reduce environmental pollution, and increase crop yields. We isolated an Enterobacter cloacae strain DJ with plant-promoting effects from the rhizosphere soil of a plant (Leymus chinensis (Trin.) Tzvel) in the western region of Jilin Province of China and investigated the mechanisms underlying the adaptation of the DJ bacteria to salinity-alkalinity environments and the molecular mechanisms of the cross-talk between DJ bacteria and cucumber seedlings.ResultsThe average diameter of the colonies on the salinity-alkalinity medium after incubation for 24 h was 3.3 cm, and this was significantly higher than the 1.9 cm diameter in ADF medium (p < 0.01). Comparative proteomic analysis revealed that 188 differentially expressed proteins, comprising 116 upregulated and 72 downregulated proteins, significantly changed in salinity-alkalinity groups compared to the control groups. The top one upregulated pathway of KEGG enrichment was bacterial chemotaxis, DJ bacteria adapted to salinity-alkalinity environments by upregulating the genes associated with bacterial chemotaxis. The contents of putrescine in salinity-alkalinity and control groups were 4.73 μg/mL and 3.02 μg/mL, whereas the contents of spermidine were 46.18 ng/mL and 0.34 ng/mL, respectively. Comparing to the control cohorts, the concentrations of both polyamines in the experimental cohorts exhibited statistically significant increases (p < 0.01). The expression of Pt gene encoding polyamine transporter protein was sharply up-regulated in cucumber roots after treatment with DJ bacteria under salinity-alkalinity stress; the expression was more than tenfold higher than that in the control groups. The enzyme activities of POD, SOD, and CAT in cucumber seedlings were higher compared to those in the control groups (p < 0.01). The stem height, number of lateral roots, and fresh weight of cucumber seedlings in the DJ treatment groups were 6.0 cm, 17 roots, and 0.42 g, respectively, whereas those of the control groups were 3.8 cm, 14 roots, and 0.28 g, respectively, with a notable difference between two cohorts (p < 0.01).ConclusionsDJ bacteria can live in salinity-alkalinity conditions by upregulating the expression of genes associated with chemotaxis. The resistance of cucumber seedlings under salinity-alkalinity conditions through the antioxidant pathway was increased by polyamines produced by DJ bacteria.Graphical

Motility behavior and physiological response mechanisms of aerobic denitrifier, Enterobacter cloacae strain HNR under high salt stress: Insights from individual cells to populations

The motility behaviors at the individual-cell level and the collective physiological responsive behaviors of aerobic denitrifier, Enterobacter cloacae strain HNR under high salt stress were investigated. The results revealed that as salinity increased, electron transport activity and adenosine triphosphate content decreased from 15.75 μg O2/g/min and 593.51 mM/L to 3.27 μg O2/g/min and 5.34 mM/L, respectively, at 40 g/L, leading to a reduction in the rotation velocity and vibration amplitude of strain HNR. High salinity stress (40 g/L) down-regulated genes involved in ABC transporters (amino acids, sugars, metal ions, and inorganic ions) and activated the biofilm-related motility regulation mechanism in strain HNR, resulting in a further decrease in flagellar motility capacity and an increase in extracellular polymeric substances secretion (4.08 mg/g cell of PS and 40.03 mg/g cell of PN at 40 g/L). These responses facilitated biofilm formation and proved effective in countering elevated salt stress in strain HNR. Moreover, the genetic diversity associated with biofilm-related motility regulation in strain HNR enhanced the adaptability and stability of the strain HNR populations to salinity stress. This study enables a deeper understanding of the response mechanism of aerobic denitrifiers to high salt stress.

Therapeutic Potential of a Novel Lytic Phage, vB_EclM_ECLFM1, against Carbapenem-Resistant Enterobacter cloacae.

The global rise of multidrug-resistant Enterobacter cloacae strains, especially those that are resistant to carbapenems and produce metallo-β-lactamases, poses a critical challenge in clinical settings owing to limited treatment options. While bacteriophages show promise in treating these infections, their use is hindered by scarce resources and insufficient genomic data. In this study, we isolated ECLFM1, a novel E. cloacae phage, from sewage water using a carbapenem-resistant clinical strain as the host. ECLFM1 exhibited rapid adsorption and a 15-min latent period, with a burst size of approximately 75 PFU/infected cell. Its genome, spanning 172,036 bp, was characterized and identified as a member of Karamvirus. In therapeutic applications, owing to a high multiplicity of infection, ECLFM1 showed increased survival in zebrafish infected with E. cloacae. This study highlights ECLFM1's potential as a candidate for controlling clinical E. cloacae infections, which would help address challenges in treating multidrug-resistant strains and contribute to the development of alternative treatments.