Serratia Sp Research Articles

Impact of the Stress Response on Quaternary Ammonium Compound Disinfectant Susceptibility in Serratia Species

The well-known problem of antibiotic resistance foreshadows a similar threat posed by microbial resistance to biocides such as disinfectants and antiseptics. These products are vital for infection control, yet their overuse during the COVID-19 pandemic has accelerated the development of resistant microorganisms. This study investigates the molecular mechanisms underlying disinfectant resistance in Serratia sp. HRI. The transcriptomic responses of Serratia sp. HRI were used to identify significant gene expression changes during exposure to QACs and revealed increased methionine transport and polyamine synthesis. Polyamines, crucial in cellular stress responses, were notably upregulated, suggesting a pivotal role of the stress response in disinfectant resistance. Further, our susceptibility tests revealed a marked decrease in susceptibility to QACs under various stress conditions, supporting the hypothesis that stress responses, mediated by polyamines, decrease susceptibility to QACs. This research highlights polyamines as key players in disinfectant resistance, offering novel insights into resistance mechanisms and antimicrobial susceptibility. Our findings emphasise the need for continued investigation into disinfectant resistance and the role of stress responses, particularly polyamine-mediated mechanisms, to direct strategies for preserving disinfectant efficacy and developing future antimicrobial agents.

Bacterial contamination of hospital-prepared enteral tube feeding formulas in Kerman, Iran

Background: Blenderized feedings continue to be used in most parts of Iran, mostly due to economic and cultural reasons. The most important problem of this kind of food is bacterial contamination. Materials and Methods: 54 samples were taken at the first and the last time of their giving to patients from blenderized food. Furthermore, 10 samples were collected from the commercial brand Fresubin® in the same way. Samples were brought to the laboratory and analyzed for the presence of some microbial pathogens. Results: Citrobacter diversus, Enterobacter cloacae, E.coli, Klebsiella pneumonia, Proteus sp, Klebsiella oxytoca, Hafnia alvei, Serratia sp, Shigella sonnei were identified from blenderized feeding. The mean bacterial contamination of 54 samples that were collected from 3 intensive care units was 5/5×106 CFU/ml. Bacterial contamination of commercial food was obtained less than 1 organism/ml. According to these results, there are significant differences between these foods. Commercial foods are the best choice for feeding patients in the hospital. Conclusion: The results indicated that a majority of the blenderized enteral tube feedings in those hospitals are not safe. In comparison to the standard limits, these enteral tube feedings are highly contaminated and pose a substantial risk of developing a foodborne disease or nosocomial infection.

Enhancing the effect of novel cd mobilization bacteria on phytoremediation and microecology of cadmium contaminated soil

The efficacy of phytoextraction for remediating heavy-metal contaminated soil depends on the bioavailability of the heavy metals and plant growth. In this study, we employed a synergistic system comprising water-soluble chitosan and the novel Cd mobilization bacteria, Serratia sp. K6 (hereafter K6), to enhance cadmium (Cd) extraction by Lolium perenne L. (ryegrass). The application of chitosan and K6 resulted in an increase in the biomass of ryegrass by 11.81% and Cd accumulation by 73.99% and effective-state Cd by 43.69% and pH decreased by 4.67%, compared to the control group. Microbiome and metabolomics analyses revealed significant alterations in the inter-root microbial ommunity, with rhizobacteria such as Sphingomonas, Nocardioides, and Bacillus likely contributing to enhanced plant growth and Cd accumulation in response to chitosan and K6 addition. Additionally, the contents of various organic acids, amino acids, lipids, and other metabolites exhibited significant changes under different additive treatments, suggesting that ryegrass can regulate its own metabolites to resist Cd stress. This study provides valuable insights into the effects of additives on phytoextraction efficiency and the soil bacterial community, offering a promising approach for phytoremediation of Cd-contaminated soils.

Assessment of homogeneous electro-Fenton process coupled with microbial fuel cell utilizing Serratia sp. AC-11 for glyphosate degradation in aqueous phase

Glyphosate (GLY), a globally-used organophosphate herbicide, is frequently detected in various environmental matrices, including water, prompting significant attention due to its persistence and potential ecological impacts. In light of this environmental concern, innovative remediation strategies are warranted. This study utilized Serratia sp. AC-11 isolated from a tropical peatland as a biocatalyst in a microbial fuel cell (MFC) coupled with a homogeneous electron-Fenton (EF) process to degrade glyphosate in aqueous medium. After coupling the processes with a resistance of 100 Ω, an output voltage value of 0.64 V was obtained and maintained stable throughout the experiment. A bacterial biofilm of Serratia sp. AC-11 was formed on the carbon felt electrode, confirmed by attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). In the anodic chamber, the GLY biodegradation rate was 100% after 48 h of experimentation, with aminomethylphosphonic acid (AMPA) remaining in the solution. In the cathodic chamber, the GLY degradation rate for the EF process was 69.5% after 48 h experimentation, with almost all of the AMPA degraded by the in situ generated hydroxyl radicals. In conclusion, the results demonstrated that Serratia sp. AC-11 not only catalyzed the biodegradation of glyphosate but also facilitated the generation of electrons for subsequent transfer to initiate the EF reaction to degrade glyphosate. This dual functionality emphasizes the unique capabilities of Serratia sp. AC-11, it as an electrogenic microorganism with application in innovative bioelectrochemical processes, and highlighting its role in sustainable strategies for environmental remediation.

Evaluation of Microbial Phospholipase and Lipase Activity Through the Chromatographic Analysis of Crude, Degummed, and Transesterified Soybean Oil for Biodiesel Production.

The present study aimed at synthesizing fatty acid methyl esters in a combined enzymatic method by applying degumming and transesterification of soybean oil. A soluble lipase from Serratia sp. W3 and a recombinant phosphatidylcholine-preferring phospholipase C (PC-PLC) from Bacillus thuringiensis were used in a consecutive manner for phosphorus removal and conversion into methyl esters. By applying 1% of recombinant PC-PLC almost 83% of phosphorus was removed (final content of 21.01mg/kg). Moreover, a sensitive and selective high-performance liquid chromatography method coupled to tandem mass spectrometry was applied to obtain a comprehensive lipid profile for the simultaneous evaluation of phospholipids removal and diacylglycerol (DAG) increase. A significant increase for all the monitored DAG species, up to 138.42%, was observed by using the enzymatic degumming, in comparison to the crude sample, resulting in an increased oil yield. Serratia sp. W3 lipase was identified as a suitable biocatalyst for biodiesel production, converting efficiently the acylglycerols. The results regarding the physical-chemical characteristics show that the cetane level, density and pour point of the obtained biodiesel are close to current regulation requirements. These findings highlight the potential of a two-step process implementation, based on the combination of lipase and phospholipase, as a suitable alternative for biodiesel production.

Differential Expression Analysis Reveals Possible New Quaternary Ammonium Compound Resistance Gene in Highly Resistant Serratia sp. HRI.

During the COVID-19 pandemic, the surge in disinfectant use emphasised their pivotal role in infection control. While the majority of antimicrobial resistance research focuses on antibiotics, resistance to biocides, which are present in disinfectants and sanitisers, is escalating. Serratia sp. HRI is a highly resistant isolate, and through the study of this organism, the molecular mechanisms of resistance may be uncovered. Serratia sp. HRI was treated with the disinfectant benzalkonium chloride in preparation for RNA sequencing. Through mining of the RNA-Seq differential expression data, an uncharacterised Major Facilitator Superfamily (MFS) efflux pump gene was found to be up-regulated at least four-fold at four different time points of exposure. Real-time PCR revealed this uncharacterised MFS efflux gene was up-regulated after exposure to benzalkonium chloride and two additional disinfectants, didecyldimethylammonium chloride (DDAC) and VirukillTM. Additionally, expression of this gene was found to be higher at 20 min versus 90 min of exposure, indicating that the up-regulation of this gene is an initial response to biocide treatment that decreases over time. This suggests that MFS efflux pumps may be an initial survival mechanism for microorganisms, allowing time for longer-term resistance mechanisms. This work puts forward a novel biocide resistance gene that could have a major impact on biocide susceptibility and resistance.

Plant endophyte immobilization technology: A promising approach for chromium-contaminated water and soil remediation

Microbial immobilization technology is considered an efficient bioremediation method for chromium (Cr) pollution. However, it is currently unclear which strain is more beneficial for the remediation of Cr-contaminated water and soil. Therefore, corn straw biochar was used as a carrier to prepare materials for fixing the endophytes Serratia sp. Y-13 (BSR1), Serratia nematodiphila (BSR2), Lysinibacillus sp. strain SePC-36 (BLB1), Lysinibacillus mangiferihumi strain WK63 (BLB2) and the commercial bacteria Shewanella oneidensis MR-1 (BSW). The results demonstrated that, compared with BSW, endophyte-loaded biochar (especially BSR1) was more effective at remediating Cr pollution in water and soil. Endophyte-loaded biochar reduced the abundance of soil pathogenic bacteria, enhanced the number of beneficial plant endophytes, reduced the soil Cr(VI) concentration, improved soil fertility, reduced the plant Cr concentration and improved the yield of lettuce. Redundancy analysis (RDA) and structural equation modelling (PLS-PM) suggested that soil microbes are closely related to soil Cr(VI), plant fresh weight and soil organic matter, whereas endophyte-loaded biochar directly influences plant cell motility pathways by altering plant microbes. This study represents a pioneering investigation into the efficacy of endophyte-loaded biochar as a remediation strategy for Cr pollution.

Bacillus, Pseudomonas and Serratia control Meloidogyne incognita (Rhabditida: Meloidogynidae) and promote the growth of tomato plants

Plant-parasitic nematodes cause significant losses in agriculture worldwide. Among these parasites, the root-knot nematode (Meloidogyne spp.) stands out. Consequently, control methods are being developed to combat this pest. Among these methods is biological control, the main agents of which are bacteria. This study aimed to evaluate the impact of 102 bacterial isolates on the mortality of Meloidogyne incognita J2 juveniles, hypothesizing that certain isolates could effectively control the nematode and promote tomato plant growth. Five experiments were conducted to test this hypothesis. First, the effect of the 102 bacterial isolates on J2 mortality was assessed under laboratory conditions. Second, five isolates (Bacillus cereus IBCBb130, Bacillus cereus IBCBb116, Pseudomonas aeruginosa IBCBb122, Bacillus proteolyticus IBCBb136, and Serratia sp. IBCBb118), which showed >68% J2 mortality, were evaluated over 72 h. Third, these isolates were tested at seven different concentrations. Fourth, their efficacy in controlling M. incognita on tomato plants was assessed in a greenhouse setting. Fifth, their potential to promote tomato plant growth without nematode inoculation was evaluated. The results revealed that the 102 bacterial isolates caused mortality ranging from 2 to 79.57% for M. incognita J2. At a 10% dilution, five isolates (B. cereus IBCBb130, P. aeruginosa IBCBb122, B. cereus IBCBb116, B. proteolyticus IBCBb136, and Serratia sp. IBCBb118) maintained mortality rates above 68%. Among these strains, B. cereus IBCBb130 and P. aeruginosa IBCBb122 were particularly effective, with B. cereus IBCBb130 showing high mortality rates under laboratory conditions and P. aeruginosa IBCBb122 significantly reducing nematode populations in greenhouse pots. Additionally, Serratia sp. IBCBb118 demonstrated notable potential for promoting tomato plant growth. In conclusion, specific bacterial isolates exhibit strong potential for the biocontrol of M. incognita and enhancement of tomato plant growth, suggesting a viable alternative to chemical nematicides. These findings provide insight into the development of sustainable agricultural practices through targeted manipulation of the soil microbiota. Future research should explore the underlying mechanisms of these interactions and their long-term effects on crop yield and soil health.

High acidity organic waste degradation and the potential to bioremediation of heavy metals in soil by an acid-tolerant Serratia sp.

Highly acidic citrus pomace (CP) is a byproduct of Pericarpium Citri Reticulatae production and causes significant environmental damage. In this study, a newly isolated acid-tolerant strain of Serratia sp. JS-043 was used to treat CP and evaluate the effect of reduced acid citrus pomace (RACP) in passivating heavy metals. The results showed that biological treatment could remove 97.56% of citric acid in CP, the organic matter in the soil increased by 202.60% and the catalase activity in the soil increased from 0 to 0.117Ug-1. Adding RACP into soil can increase the stabilization of Cu, Zn, As, Co, and Pb. Specifically, through the metabolism of strain JS-043, RACP was also involved in the stabilization of Zn and Pb, and Residual Fraction in the total pool of these metals increased by 10.73% and 10.54%, respectively. Finally, the genome sequence of Serratia sp. JS-043 was completed, and the genetic basis of its acid-resistant and acid-reducing characteristics was preliminarily revealed. JS-043 also contains many genes encoding proteins associated with heavy metal ion tolerance and transport. These findings suggest that JS-043 may be a high-potential strain to improve the quality of acidic organic wastes that can then be useful for soil bioremediation.

ROK family regulator NagC promotes prodigiosin biosynthesis independent of N-acetylglucosamine in Serratia sp. ATCC 39006.

The ROK family transcription factor NagC is an important global regulator in the γ-proteobacteria. A large number of genes involved in the transport and metabolism of sugars, as well as those associated with biofilm formation and pathogenicity, are regulated by NagC. In all of these regulations, the transcriptional regulatory activity of NagC responds to the supply of GlcNAc in the environment. Here, we found for the first time that NagC can regulate antibiotic biosynthesis, whose transcriptional regulatory activity is independent of GlcNAc. This suggests that NagC may respond to more signals and regulate more physiological processes in Gram-negative bacteria.

Optimization of Growth Response Parameters, Screening and Molecular Detection of Pesticide Degradation Genes in Bacterial Isolates from Agricultural Soils

Study’s Novelty/ Excerpt This study demonstrated the capability of bacteria isolated from farmland soils in Kano Metropolis to biodegrade dichlorvos and carbofuran pesticides, identifying Bacillus sp., Serratia sp., and Pseudomonas sp. as key degraders. Optimization experiments revealed that Serratia sp. thrived at 100 mg/L dichlorvos concentration and 35°C, while Pseudomonas sp. showed maximum growth at 300 mg/L carbofuran concentration and 30°C, both with a pH of 7.0, 100 rpm agitation, and 5-day incubation period. Molecular analysis confirmed the presence of opd and mcd genes in Serratia sp. and Pseudomonas sp., respectively, highlighting their potential for effective bioremediation of pesticide-contaminated soils. Full Abstract Pesticides are organic compounds synthesized and used for pest control. The excessive and continuous dispersion of pesticides in the environment results in environmental pollution, necessitating remediation. This study investigated the potential of bacteria isolated from farmland soils in Kano Metropolis, Kano State, Nigeria, with a history of dichlorvos (2,2-dichlorovinyldimethylphosphate) and carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) application, to biodegrade these pesticides. Three sampling sites were involved in sample collection, and the soil physicochemical parameters from each sample were determined. Isolation, identification, and screening of the bacterial isolates capable of utilizing the pesticides as sole sources of carbon were carried out. The following parameters (concentration of the pesticides, pH, temperature, agitation, and incubation time) were optimized to maximize degradation. The potent bacterial isolates were further subjected to molecular analysis for the detection of opd and mcd genes. The pesticide-degrading bacteria were identified as Bacillus sp., Serratia sp., and Pseudomonas sp. Serratia sp. recorded the highest growth in the presence of 1% v/v dichlorvos, while Pseudomonas sp. exhibited maximum growth at a 1% w/v carbofuran concentration. The optimized conditions that yielded the maximum microbial growth are: 100 mg/L pesticide concentration for Serratia sp and 300 mg/L for Pseudomonas sp, a pH of 7.0 and an agitation level of 100 rpm for both organisms, a temperature of 35°C for Serratia sp and 30°C for Pseudomonas sp, and an incubation time of 5 days for both organisms. The opd and mcd genes were identified from Serratia sp. and Pseudomonas sp. respectively. These results suggest that the isolated bacteria have the potential to degrade dichlorvos and carbofuran pesticides from the contaminated soil

Efficient Chitin Extraction from Shrimp Exoskeletons through Single-Step Fermentation by Pseudomonas aeruginosa QF50 and Serratia sp. QCS23

Chitin, an abundant biopolymer with potential applications in agriculture, medicine, and bioremediation, is conventionally extracted using chemical methods that have environmental disadvantages. This study investigates the extraction of chitin from Litopenaeus vannamei shrimp waste by one-step fermentation using the bacterial strains Pseudomonas aeruginosa QF50 and Serratia sp. QCS23. A total of 4 kg of shrimp waste was treated by fermentation with culture media enriched with different concentrations of glucose (1, 5, and 10%) for 7 days at 25 °C, followed by purification and characterization processes using infrared spectroscopy and X-ray diffraction. The results demonstrated an increase in the yield of crude chitin proportional to the glucose concentration, reaching a maximum of 76.81 ± 7.64% for Pseudomonas aeruginosa QF50 and 71.30 ± 1.16% for Serratia sp. QCS23. Both strains showed high efficiencies in deproteinization (80–87%) and demineralization, with significant improvements especially shown at high glucose concentrations. Structural characterization confirmed the presence of the spectral characteristics of α-chitin, with crystallinity indices of 81% and 71% for chitins obtained with Pseudomonas aeruginosa QF50 and Serratia sp. QCS23, respectively. This study concludes that single-step fermentation with Pseudomonas aeruginosa QF50 and Serratia sp. QCS23 is an effective and sustainable method for the extraction of high-quality chitin from shrimp exoskeleton waste, offering a promising alternative to traditional chemical methods.

Comparative genomics of plant growth promoting phosphobacteria isolated from acidic soils.

Despite being one of the most abundant elements in soil, phosphorus (P) often becomes a limiting macronutrient for plants due to its low bioavailability, primarily locked away in insoluble organic and inorganic forms. Phosphate solubilizing and mineralizing bacteria, also called phosphobacteria, isolated from P-deficient soils have emerged as a promising biofertilizer alternative, capable of converting these recalcitrant P forms into plant-available phosphates. Three such phosphobacteria strains-Serratia sp. RJAL6, Klebsiella sp. RCJ4, and Enterobacter sp. 198-previously demonstrated their particular strength as plant growth promoters for wheat, ryegrass, or avocado under abiotic stresses and P deficiency. Comparative genomic analysis of their draft genomes revealed several genes encoding key functionalities, including alkaline phosphatases, isonitrile secondary metabolites, enterobactin biosynthesis and genes associated to the production of indole-3-acetic acid (IAA) and gluconic acid. Moreover, overall genome relatedness indexes (OGRIs) revealed substantial divergence between Serratia sp. RJAL6 and its closest phylogenetic neighbours, Serratia nematodiphila and Serratia bockelmanii. This compelling evidence suggests that RJAL6 merits classification as a novel species. This in silico genomic analysis provides vital insights into the plant growth-promoting capabilities and provenance of these promising PSRB strains. Notably, it paves the way for further characterization and potential application of the newly identified Serratia species as a powerful bioinoculant in future agricultural settings.

Development of biocomposite films incorporated with the extract from pitcher associated bacteria for the postharvest protection from fungi.

Pythium aphanidermatum is known to cause diseases likedamping-off, root rot, stem rot and fruit rot in a wide range of plants. Eventhough many chemical methods have been demonstrated to have the potential to manage these diseases, their benefits are being offset equally by the negative side effects. Therefore, the control of Pythium spp. using natural antifungal agents is of immense significance due to its environmental safety. Here, the plant associated microorganisms with antifungal metabolites have significant promises to be explored both as sustainable biocontrol agents and also as active constituents of antifungal materials. Antimicrobial packaging films prepared using such components can have significant applications to meet the requirements to prevent postharvest loss of agricultural produce by inhibiting the fungal growth. Eventhough there are reports on the development of antimicrobial packaging films for such applications, the use of bacterial extracts with antifungal activity for the same is least investigated. Hence, the present study demonstrates the development of biocomposite films prepared using polyvinyl alcohol (PVA) incorporated with the extracts prepared from bacterial isolates (Serratia sp. NhPB1, Kocuria sp. NhPB49, and Pantoea dispersa NhPB54) previously isolated from the pitcher plant. Here, the individual films were prepared by incorporating 1mL of bacterial extract in 40mL of 3% PVA solution and the developed films were then subjected to antifungal activity screening against P. aphanidermatum. The antifungal activity analysis of the films prepared with the incorporation of extracts from Serratia sp. NhPB1, Kocuria sp. NhPB49, and Pantoea dispersa NhPB54 showed remarkable activity against the tested pathogen. The application of biocomposite films on Solanum lycopersicum and Capsicum annuum fruits for its protection from P. aphanidermatum by dip coating method further indicates the promises of developed biocomposite films for active packaging applications.

Halophilic Plant Growth-Promoting Rhizobacteria as Producers of Antifungal Metabolites under Salt Stress

Salinity is one of the main factors causing soil deterioration, making it unsuitable for agriculture. It is well documented that the application of halotolerant and halophilic plant growth-promoting bacteria (PGPR: plant growth-promoting rhizobacteria) with biological control activities as an inoculant of cultivated plants offers a biological alternative to the use of agrochemicals, particularly when subjected to salt stress. From this perspective, 70 bacterial strains were isolated from saline soils (sebkha) in arid and semi-arid areas of Eastern Algeria. Three isolates were selected based on their ability to produce bioactive molecules allowing them to promote plant growth, such as hydrolytic enzymes, indole acetic acid (auxin-phytohormone), HCN, NH3, etc. Two of these isolates belonged to the genus Serratia and the third was a halophilic Halomonas bacteria. These bacteria were identified based on their 16S rDNA sequences. Antagonism tests against phytopathogenic fungi were carried out. The identification of the antifungal molecules produced by these bacteria was determined using high-performance liquid chromatography. These bacteria can inhibit mycelial development against phytopathogenic fungi with rates reaching 80.67% against Botrytis cinerea, 76.22% against Aspergillus niger, and 66.67% against Fusarium culmorum for Serratia sp. The strain Halomonas sp. inhibited mycelial growth through the production of volatile substances of Aspergillus niger at 71.29%, Aspergillus flavus at 75.49%, and Penicillium glabrum at a rate of 72.22%. The identification of the antifungal molecules produced by these three bacteria using HPLC revealed that they were polyphenols, which makes these strains the first rhizobacteria capable of producing phenolic compounds. Finally, pot tests to determine the effectiveness of these strains in promoting wheat growth under salinity stress (125 mM, 150 mM, and 200 mM) was carried out. The results revealed that a consortium of two isolates (Serratia sp. and Halomonas sp.) performed best at 125 mM. However, at higher concentrations, it was the halophilic bacteria Halomonas sp. that gave the best result. In all cases, there was a significant improvement in the growth of wheat seedlings inoculated with the bacteria compared to non-inoculated controls.

Microbial Community Changes in Silkworms Suspected of Septicemia and Identification of Serratia sp.

Diseases that occur in silkworms include soft rot, hardening disease, digestive diseases, and sepsis. However, research on the causes of bacterial diseases occurring in silkworms and the resulting changes in the microbial community is lacking. Therefore, we examined the morphological characteristics of sepsis and changes in the microbial community between silkworms that exhibit a unique odor and healthy silkworms; thus, we established a relationship between disease-causing microorganisms and sepsis. After producing a 16S rRNA amplicon library for samples showing sepsis, we obtained information on the microbial community present in silkworms using next-generation sequencing. Compared to that in healthy silkworms, in silkworms with sepsis, the abundance of the Firmicutes phylum was significantly reduced, while that of Proteobacteria was increased. Serratia sp. was dominant in silkworms with sepsis. After bacterial isolation, identification, and reinfection through the oral cavity, we confirmed this organism as the disease-causing agent; its mortality rate was 1.8 times higher than that caused by Serratia marcescens. In summary, we identified a new causative bacterium of silkworm sepsis through microbial community analysis and confirmed that the microbial community balance was disrupted by the aberrant proliferation of certain bacteria.

Effects of biochar immobilization of Serratia sp. F4 OR414381 on bioremediation of petroleum contamination and bacterial community composition in loess soil

Petroleum hydrocarbons pose a significant threat to human health and the environment. Biochar has increasingly been utilized for soil remediation. This study investigated the potential of biochar immobilization using Serratia sp. F4 OR414381 for the remediation of petroleum-contaminated soil through a pot experiment conducted over 90 days. The treatments in this study, denoted as IMs (maize straw biochar-immobilized Serratia sp. F4), degraded 82.5% of the total petroleum hydrocarbons (TPH), 59.23% of the aromatic, and 90.1% of the saturated hydrocarbon fractions in the loess soils. During remediation, the soil pH values decreased from 8.76 to 7.33, and the oxidation-reduction potential (ORP) increased from 156 to 229 mV. The treatment-maintained soil nutrients of the IMs were 138.94 mg/kg of NO3- -N and 92.47 mg/kg of available phosphorus (AP), as well as 11.29% of moisture content. The activities of soil dehydrogenase (SDHA) and catalase (CAT) respectively increased by 14% and 15 times compared to the CK treatment. Three key petroleum hydrocarbon degradation genes, including CYP450, AJ025, and xylX were upregulated following IMs treatment. Microbial community analysis revealed that a substantial microbial population of 1.01E+ 09 cells/g soil and oil-degrading bacteria such as Salinimicrobium, Saccharibacteria_genera_incertae_sedis, and Brevundimonas were the dominant genera in IMs treatment. This suggests that the biochar immobilized on Serratia sp. F4 OR414381 improves soil physicochemical properties and enhances interactions among microbial populations, presenting a promising and environmentally friendly approach for the stable and efficient remediation of petroleum-contaminated loess soil.

Integrated physiological, biochemical and transcriptomic analyses reveal the mechanism of salt tolerance induced by a halotolerant Serratia sp. NTN6 in maize

Salt stress is a serious environmental challenge that hinders crop growth and yield. Plant growth-promoting rhizobacteria (PGPR) can successfully and environmentally friendly boost plant development in saline soils. In this study, a halotolerant Serratia sp. NTN6 was isolated from the rhizosphere soil of halophyte Puccinellia tenuiflora and its plant growth-promoting properties were determined. NTN6 inoculation significantly promoted seed germination and seedling growth in maize under salt stress. Shoot height, stem thickness, root fresh weight, shoot fresh weight, root dry weight, and shoot dry weight of salt-stressed seedlings increased by 36.3%, 32.5%, 146.4%, 193.6%, 25.0%, and 109.6%, respectively, after inoculation with NTN6. NTN6-mediated maize salt tolerance was revealed via transcriptomic, physiological, and biochemical analyses. Under salt stress, NTN6 regulated the transcript levels of genes related to chlorophyll synthesis, photosynthesis apparatus, and carbon assimilation pathways, and thus increasing chlorophyll content, Fv/Fm, and net photosynthetic rate; NTN6 reduced the content of O2•–, H2O2, and MDA by regulating the transcripts and activities of antioxidant enzymes; NTN6 affected the transcriptional response of genes involved in ABA synthesis and signaling to salt stress and reduced ABA level. Finally, NTN6 boosted photosynthetic capacity in salt-stressed maize by modulating photochemical activity, C4 pathway and Calvin cycle as well as mitigating reactive oxygen species damage to the photosystem reaction center. This study first investigated the mechanism of Serratia sp.-induced salt tolerance in maize and these findings demonstrate the valuable contribution of halotolerant PGPR strain from halophytes in improving salinity tolerance in non-halophytic crops.

Prodigiosin: An In-depth Exploration of a Bioactive Compound from Serratia sp.

Background:: The rising interest in natural pigments as alternatives is a result of the expanding usage of synthetic colorants and the negative consequences that go along with them. Noble natural pigments with higher stability and productivity are becoming popular in the food industry, and their diverse biological characteristics make them valuable for pharmaceutical applications. Microbes, especially gram-negative and positive bacteria, are considered attractive sources for replacing synthetic dyes. Prodigiosin, a tripyrrole red pigment produced as secondary metabolites by these bacteria, exhibits unusual properties and has potential as an effective proapoptotic agent against cancer and multi-drug resistant cells. Objective:: This review aims to highlight the characteristics of prodigiosin and explore its potential applications as a therapeutic drug. Results:: The review investigates the biosynthetic cluster genes of prodigiosin identified using the EZ-Tn5 transposon approach in different bacteria, including the pig gene cluster in Serratia sp., red gene cluster in S. coelicolor, and hap gene cluster in Hahella chejuensis. It is also described compound nature for producing host survival physiology. Prodigiosin has a common pyrrolyl Promethean structure and is a member of the tripyrrole family. Numerous tri-pyrrole derivatives have been used in antibiotics and have demonstrated promise as pro-apoptotic agents against cancer and drug-resistant cells. Conclusion:: Prodigiosin is an intriguing subject for investigating biosynthesis and exploitation through biotechnological methods due to its distinctive properties and potential as a medicinal medication. Future investigation and bioengineering on producing strains may synthesize functional derivatives with diverse applications.

A novel perspective on eugenol as a natural anti-quorum sensing molecule against Serratia sp.

Serratia marcescens is commonly noted to be an opportunistic pathogen and is often associated with nosocomial infections. In addition to its high antibiotic resistance, it exhibits a wide range of virulence factors that confer pathogenicity. Targeting quorum sensing (QS) presents a potential therapeutic strategy for treating bacterial infections caused by S. marcescens, as it regulates the expression of various virulence factors. Inhibiting QS can effectively neutralize S. marcescens' bacterial virulence without exerting stress on bacterial growth, facilitating bacterial eradication by the immune system. In this study, the antibacterial and anti-virulence properties of eugenol against Serratia sp. were investigated.Eugenol exhibited inhibitory effects on the growth of Serratia, with a minimal inhibitory concentration (MIC) value of 16.15 mM. At sub-inhibitory concentrations, eugenol also demonstrated antiadhesive and eradication activities by inhibiting biofilm formation. Furthermore, it reduced prodigiosin production and completely inhibited protease production. Additionally, eugenol effectively decreased swimming and swarming motilities in Serratia sp. This study demonstrated through molecular modeling, docking and molecular dynamic that eugenol inhibited biofilm formation and virulence factor production in Serratia by binding to the SmaR receptor and blocking the formation of the HSL-SmaR complex. The binding of eugenol to SmaR modulates biofilm formation and virulence factor production by Serratia sp. These findings highlight the potential of eugenol as a promising agent to combat S. marcescens infections by targeting its virulence factors through quorum sensing inhibition.