Maltophilia Strain Research Articles

Antimicrobial Susceptibility, Minimum Inhibitory Concentrations, and Clinical Profiles of Stenotrophomonas maltophilia Endophthalmitis.

Stenotrophomonas maltophilia has been reported in various ocular infections, including keratitis, conjunctivitis, preseptal cellulitis, and endophthalmitis, all of which may lead to vision loss. However, the S. maltophilia strain is resistant to a wide variety of antibiotics, including penicillins, third-generation cephalosporins, aminoglycosides, and imipenem. In this study, we retrospectively reviewed the clinical characteristics, antibiotic susceptibility, antimicrobial minimum inhibitory concentrations (MICs), and visual outcomes for S. maltophilia endophthalmitis. The data of 9 patients with positive S. maltophilia cultures in a tertiary referral center from 2010 to 2019 were reviewed. Cataract surgery (n = 8, 89%) was the most common etiology, followed by intravitreal injection (n = 1, 11%). S. maltophilia’s susceptibility to levofloxacin and moxifloxacin was observed in 6 cases (67%). Seven isolates were resistant to sulfamethoxazole-trimethoprim (78%). The MIC90 for S. maltophilia was 256, 256, 256, 8, 12, 12, 12, and 8 μg/mL for amikacin, cefuroxime, ceftazidime, tigecycline, sulfamethoxazole-trimethoprim, levofloxacin, galtifloxacin, and moxifloxacin, respectively. Final visual acuity was 20/200 or better in 5 patients (56%). Fluoroquinolones and tigecycline exhibited low antibiotic MIC90. Therefore, the results suggest that fluoroquinolones can be used as first-line antibiotics for S. maltophilia endophthalmitis.

Comparative insights into multiple drug resistance determinants in Stenotrophomonas maltophilia MER1

ObjectivesMultidrug-resistant (MDR) Stenotrophomonas maltophilia strain MER1 was isolated from hospital wastewater in Shandong Province, China. This study aimed to determine the genetic determinants related to its striking MDR phenotype. MethodsAntimicrobial susceptibility testing of strain MER1 was performed by disk diffusion on Mueller–Hinton agar plates, and MICs were interpreted according to Clinical and Laboratory Standards Institute breakpoints. The genome of MER1 was sequenced and assembled using PacBio RS II and BGISEQ-500 platforms. Antimicrobial resistance determinants together with other transferability or adaptability determinants were identified by comparative genomics. Phylogenetic and contextual assays for these elements were conducted to assess the risk of spread of MER1. ResultsAntimicrobial susceptibility testing revealed that strain MER1 is resistant to nine different antibiotics, including ampicillin, meropenem, amikacin, erythromycin, vancomycin, tetracycline, tigecycline, colistin and ceftazidime. Several genes were identified encoding efflux pumps and drug-inactivating agents, accounting for resistance to the above antibiotics, including meropenem, tigecycline and colistin regarded as last-line therapies for infections caused by MDR Gram-negative bacteria. MER1 co-harbours two non-mobile mcr homologues. A novel genomic region of variability was demonstrated to confer bacterial robustness and adaptability upon strain MER1. ConclusionCollective efforts revealed the MDR properties and potential genetic determinants of S. maltophilia MER1 isolated from hospital wastewater. Comparative genomic analysis of S. maltophilia MER1 may provide insights into the prevention and treatment of antimicrobial-resistant infections. Our findings raise concern that the MDR genes in the reservoir of S. maltophilia may further spread into various ecological niches or medically high-risk pathogens.

Structural insights into the mechanism of pH-selective substrate specificity of the polysaccharide lyase Smlt1473

Polysaccharide lyases (PLs) are a broad class of microbial enzymes that degrade anionic polysaccharides. Equally broad diversity in their polysaccharide substrates has attracted interest in biotechnological applications such as biomass conversion to value-added chemicals and microbial biofilm removal. Unlike other PLs, Smlt1473 present in the clinically relevant Stenotrophomonas maltophilia strain K279a demonstrates a wide range of pH-dependent substrate specificities toward multiple, diverse polysaccharides: hyaluronic acid (pH 5.0), poly-β-D-glucuronic (celluronic) acid (pH 7.0), poly-β-D-mannuronic acid, and poly-α-L-guluronate (pH 9.0). To decode the pH-driven multiple substrate specificities and selectivity in this single enzyme, we present the X-ray structures of Smlt1473 determined at multiple pH values in apo and mannuronate-bound states as well as the tetra-hyaluronate-docked structure. Our results indicate that structural flexibility in the binding site and N-terminal loop coupled with specific substrate stereochemistry facilitates distinct modes of entry for substrates having diverse charge densities and chemical structures. Our structural analyses of wild-type apo structures solved at different pH values (5.0–9.0) and pH-trapped (5.0 and 7.0) catalytically relevant wild-type mannuronate complexes (1) indicate that pH modulates the catalytic microenvironment for guiding structurally and chemically diverse polysaccharide substrates, (2) further establish that molecular-level fluctuation in the enzyme catalytic tunnel is preconfigured, and (3) suggest that pH modulates fluctuations resulting in optimal substrate binding and cleavage. Furthermore, our results provide key insight into how strategies to reengineer both flexible loop and regions distal to the active site could be developed to target new and diverse substrates in a wide range of applications.

The use of Aloe Vera Gel Functionalized Biogenic Zinc-Oxide Nanoparticles Against Fish Putative Pathogens

Indiscriminate uses of antibiotics have resulted in the development of antibiotic-resistance among pathogens which possess a potential risk to the ecosystem, aquaculture and human health. In this study, biogenic zinc oxide nanoparticles (ZnO-NPs) were synthesized using aqueous extract of Aloe vera gel (AVGE) and tested against putative pathogenic bacterial strains in-vitro. Ultraviolet-Visible (UV-VIS) spectroscopic analysis confirmed the synthesis of AVGE-ZnO-NPs while X-ray diffraction (XRD) and Scanning Electron microscope (SEM) analysis revealed that the average size of synthesized ZnO-NPs is within the nano range. The elemental and chemical compositions of synthesized ZnO-NPs were studied using Energy-dispersive X-ray spectroscopy (EDX) and Fourier-transform infrared (FTIR) spectrometer, respectively. Two widespread bacterial strains, Aeromonas veronii strain ONKP1 (MN602971) and Stenotrophomonas maltophilia strain ONKP2 (MN602972) that are known as emerging opportunistic pathogens in various marine and freshwater fishes as well as humans and other animals, were used as test organisms. AVGE-ZnO-NPs showed strong antibacterial activity, against the tested Gram-negative multi-drug resistant bacteria in the disc diffusion assay. The results of the present investigation could be useful for the development of new disease management strategies in the fisheries industry.

Biological characteristics and genomic analysis of a Stenotrophomonas maltophilia phage vB_SmaS_BUCT548.

Stenotrophomonas maltophilia (hereinafter referred to as S. maltophilia) has developed into an important opportunistic pathogenic bacterium, which is prevalent in nosocomial and community infections, and has adverse effects on patients with a compromised immune system. Phage vB_SmaS_BUCT548 was isolated from sewage of Beijing 307 Hospital with S. maltophilia (strain No.824) as a host. Phage morphology was observed by transmission electron microscopy and its biological and genomic characteristics were determined. The electron microscope shows that the bacteriophage belonged to the Siphoviridae and MOI is 0.001. One-step growth curve shows that the incubation period is 30min and the burst size is 134 PFU/Cell. The host range is relatively wide and it can lysis 11of 13 S. maltophilia strains. Next-Generation Sequencing (NGS) results show that the genome sequence is a dsDNA with 62354bp length, and the GC content is 56.3% (GenBank: MN937349). One hundred and two online reading frames (ORFs) are obtained after RAST online annotation and the BlastN nucleic acid comparison shows that the phage had low homology with other phages in NCBI database. This study reports a novel S. maltophilia phage named vB_SmaS_BUCT548, which has a short incubation period, strong lytic ability, and a wide host range. The main characteristic of this bacteriophage is the novelty of the genomic sequence and the analysis of the other characteristics provides basic data for further exploring the interaction mechanism between the phage and the host.

Simultaneous denitrification and hexavalent chromium removal by a newly isolated Stenotrophomonas maltophilia strain W26 under aerobic conditions

Environmental contextIndustrial development has caused the release of hexavalent chromium and nitrates into the environment. Interactions of hexavalent chromium and nitrates with microorganisms are important both for understanding environmental behaviour and for treatment options. Bacterial removal of both chromium and nitrate was optimised in waters relevant to waste streams and the environment. Abstract An isolated strain of the bacterium Stenotrophomonas maltophilia strain W26, is shown to be capable of the simultaneous removal of nitrate and CrVI under aerobic conditions. Notably, 10mg L−1 of CrVI and 500mg L−1 of nitrate were reduced by 92.6% and 85.2%, respectively, by strain W26. Results showed that an excellent denitrification efficiency of 96.0% could be reached at the optimal conditions of a C/N ratio of 10, using a carbon source of trisodium citrate, at pH 7.5, and a nitrate concentration of 500mg L−1. Strain W26 could also effectively remove high concentrations of CrVI (50mg L−1, 93.2%) and nitrate (700mg L−1, 97.4%). By using the N balance analysis, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), the denitrification and CrVI transformation processes were verified. CrVI, immobilised on the cell surface by W26, was reduced to CrIII, through interaction with of O=C and N-H groups. This study indicates that the isolated strain W26 has the potential to treat wastewater containing combined nitrate and CrVI contamination.

Draft genome sequence of Stenotrophomonas maltophilia strain P13 gives insight into its protease production and assessment of sulfur and nitrogen metabolism.

Stenotrophomonas maltophilia strain P13 was isolated from the Kanchengayao glacier's accumulation zone. A comprehensive study was done on this strain as it produced protease enzyme and thus having industrial potential. The whole genome sequence, FAME, morphological and biochemical characteristics of the S. maltophilia strain P13 is being presented. The genome of P13 strain possesses 2,689,565 total reads, with an average G + C content of 69.9%. The whole-genome assembly is having 548 contigs (with PEGs). The genome contains 2,985 coding sequences with 55 rRNA predicted genes. More than 88% of the total pre-processed reads from samples were mapped. The identified coding proteins were classified into 27 functional categories based on COG classification. The genome was found to possess genes for ammonium assimilation, galactosylceramide and sulfatide metabolism. The major enzymes present are beta-galactosidase, thiol peroxidase, thiolredoxin reductase, glutamate synthase, and glutamate-ammonia-ligase adenyltransferase. The genome information of Stenotrophomonas maltophilia P13 provides the basis for understanding the functional properties and abilities to act as a potential cold-activeenzyme producer and nitrogen-fixing bacteria.

Characteristic antimicrobial resistance of clinically isolated Stenotrophomonas maltophilia CYZ via complete genome sequence

ObjectivesStenotrophomonas maltophilia is an important multidrug-resistant pathogen that is associated with various serious nosocomial infections. In our study, we investigated the antimicrobial resistance traits of clinical S. maltophilia strain CYZ isolated from the sputum of an immunocompromised patient. MethodsThe whole genome sequence of S. maltophilia CYZ was investigated using a PacBio RS II system. The functions of all the predicted genes were annotated by the COG, GO and KEGG databases. Several types of antibiotics were selected to test the antimicrobial susceptibility, and a phylogenetic tree was constructed based on 16S rRNA gene sequence. ResultsThe genome of S. maltophilia CYZ has a length of 4,517,685 bp and contains 4077 predicted genes, with an average G + C content of 66.65%. Functional genomic analysis via the annotations of the COG and GO databases revealed that the isolate exhibited specific means to resist antibiotics. The annotated genes involved in flagella, pili or fimbriae, biofilm formation, polysaccharide and cyclic di-GMP may contribute to promote the ability of antimicrobial resistance. This strain showed susceptibility to levofloxacin, trimethoprim/sulfamethoxazole and minocycline according to antimicrobial susceptibility testing. The phylogenetic relationship indicated that S. maltophilia CYZ was closely related to S. maltophilia strains isolated from the nosocomial environment. ConclusionsThe current results give a better understanding of the genetic characteristics of antimicrobial resistance in S. maltophilia CYZ and provide a genetic basis for further study of the phenotype.

Identification and characterization of differentially expressed genes in Caenorhabditis elegans in response to pathogenic and nonpathogenic Stenotrophomonas maltophilia

BackgroundStenotrophomonas maltophilia is an emerging nosocomial pathogen that causes infection in immunocompromised patients. S. maltophilia isolates are genetically diverse, contain diverse virulence factors, and are variably pathogenic within several host species. Members of the Stenotrophomonas genus are part of the native microbiome of C. elegans, being found in greater relative abundance within the worm than its environment, suggesting that these bacteria accumulate within C. elegans. Thus, study of the C. elegans-Stenotrophomonas interaction is of both medical and ecological significance. To identify host defense mechanisms, we analyzed the C. elegans transcriptomic response to S. maltophilia strains of varying pathogenicity: K279a, an avirulent clinical isolate, JCMS, a virulent strain isolated in association with soil nematodes near Manhattan, KS, and JV3, an even more virulent environmental isolate.ResultsOverall, we found 145 genes that are commonly differentially expressed in response to pathogenic S. maltophilia strains, 89% of which are upregulated, with many even further upregulated in response to JV3 as compared to JCMS. There are many more JV3-specific differentially expressed genes (225, 11% upregulated) than JCMS-specific differentially expressed genes (14, 86% upregulated), suggesting JV3 has unique pathogenic mechanisms that could explain its increased virulence. We used connectivity within a gene network model to choose pathogen-specific and strain-specific differentially expressed candidate genes for functional analysis. Mutations in 13 of 22 candidate genes caused significant differences in C. elegans survival in response to at least one S. maltophilia strain, although not always the strain that induced differential expression, suggesting a dynamic response to varying levels of pathogenicity.ConclusionsVariation in observed pathogenicity and differences in host transcriptional responses to S. maltophilia strains reveal that strain-specific mechanisms play important roles in S. maltophilia pathogenesis. Furthermore, utilizing bacteria closely related to strains found in C. elegans natural environment provides a more realistic interaction for understanding host-pathogen response.

Complete Genome Sequence of Stenotrophomonas maltophilia Strain CPBW01, Isolated from the Wings of the Colorado Potato Beetle in Xinjiang, China.

Bacteria of the genus Stenotrophomonas are opportunistic and have been documented in the guts of several insect species. Here, we present the complete genome sequence of S. maltophilia strain CPBW01, isolated from the wings of the Colorado potato beetle, Leptinotarsa decemlineata, collected from potato fields in Urumqi (43.71N, 87.39E), Xinjiang, China.

Draft Genome Sequence of Stenotrophomonas maltophilia CRB139-1, Isolated from Poultry Meat in Japan.

Stenotrophomonas maltophilia is a nosocomial pathogen that primarily causes respiratory infection in humans. This pathogen is widely distributed in the environment, including in foods. Here, we report the draft genome sequence of S. maltophilia strain CRB139-1, isolated from poultry meat in Japan. The genome size was 4,619,918 bp at 90× coverage.

Characteristics and Ice Nucleation Activity of Sugarcane Epiphytic and Endophytic Bacteria and Their Role in Host Frostbite

Sugarcane is one of the most important economic plants in tropical and subtropical regions worldwide, which is exposed to damage in cold condition. This study was conducted to characterize the epiphytic and endophytic bacteria and investigation of their role in ice nucleation activity and host frostbite. During the survey in spring and summer 2015, a total of 136 Gram-negative and Gram-positive bacterial strains were isolated from main sugarcane fields, especially Ahwaz sugarcane agro-industries in the south of Iran. According to phenotypic features and sequences of 16S rRNA encoding genes of sugarcane epiphytic and endophytic bacteria, they belonged to six families including Pseudomonadaceae, Xanthomonadaceae, Enterobacteriaceae, Sphingomonadaceae, Microbacteriaceae and Bacillaceae. Representatives of these families were identified as Pseudomonas fluorescens (Epi57-A4), Pseudomonas marginalis (strain Epi48-A17), Pseudomonas putida (strain Epi57-I6), Xanthomonas axonopodis strain (Endo57-A8), Stenotrophomonas maltophilia (strain Endo69-A6), Pseudomonas geniculata strain (Epi69-A4), Pantoea stewartii (strain Epi57-I8), Sphingomonas sp. (strain Epi48-A7), Microbacterium arborescens (strain Epi69-I1) and Bacillus sp. (strain Epi48-A8). The highest frequency of the tested bacterial strains was observed for Pseudomonadaceae and Xanthomonadaceae family members. Pseudomonas fluorescens strain Epi57-A4 and Pantoea stewartii strain Epi57-I8 showed ice nucleation activity in ethanol bath and caused frost damage on sugarcane seedlings in vitro. Amplification of Ice nucleation gene using degenerate inaprimers showed that only Pseudomonas fluorescens strain Epi57-A4 was ina+ gene, suggesting the potential of this gene to accelerate frosting in sugarcane during the cold condition.

Novel Stenotrophomonas maltophilia temperate phage DLP4 is capable of lysogenic conversion

BackgroundTemperate bacteriophages are capable of lysogenic conversion of new bacterial hosts. This phenomenon is often ascribed to “moron” elements that are acquired horizontally and transcribed independently from the rest of the phage genes. Whereas some bacterial species exhibit relatively little prophage-dependent phenotypic changes, other bacterial species such as Stenotrophomonas maltophilia appear to commonly adopt prophage genetic contributions.ResultsThe novel S. maltophilia bacteriophage DLP4 was isolated from soil using the highly antibiotic-resistant S. maltophilia strain D1585. Genome sequence analysis and functionality testing showed that DLP4 is a temperate phage capable of lysogenizing D1585. Two moron genes of interest, folA (BIT20_024) and ybiA (BIT20_065), were identified and investigated for their putative activities using complementation testing and phenotypic and transcriptomic changes between wild-type D1585 and the D1585::DLP4 lysogen. The gp24 / folA gene encodes dihydrofolate reductase (DHFR: FolA), an enzyme responsible for resistance to the antibiotic trimethoprim. I-TASSER analysis of DLP4 FolA predicted structural similarity to Bacillus anthracis DHFR and minimum inhibitory concentration experiments demonstrated that lysogenic conversion of D1585 by DLP4 provided the host cell with an increase in trimethoprim resistance. The gp65 / ybiA gene encodes N-glycosidase YbiA, which in E. coli BW25113 is required for its swarming motility phenotype. Expressing DLP4 ybiA in strain ybiA770(del)::kan restored its swarming motility activity to wildtype levels. Reverse transcription-PCR confirmed the expression of both of these genes during DLP4 lysogeny.ConclusionsS. maltophilia temperate phage DLP4 contributes to the antibiotic resistance exhibited by its lysogenized host strain. Genomic analyses can greatly assist in the identification of phage moron genes potentially involved in lysogenic conversion. Further research is required to fully understand the specific contributions temperate phage moron genes provide with respect to the antibiotic resistance and virulence of S. maltophilia host cells.

Molecular identification of <i>Fusarium</i> spp. from wilt-infected tomato and brinjal plants in selected regions of Sri Lanka and endophytic bacteria as a potential option for disease management

Fusarium wilt caused by Fusarium spp. is an economically important fungal disease of tomato and brinjal production areas in Sri Lanka. The study was carried out to identify Fusarium isolates infecting tomato and brinjal, and endophytic antagonists bacteria against Fusarium wilt pathogen. The infected tomato and brinjal samples were collected from farmers’ fields in Matale, Kandy, Nuwara Eliya and Badulla districts and PCR was conducted using primers specific for species, races and formae speciales. Eight, nine and five isolates were identified as Fusarium solani, Fusarium oxysporum f. sp. lycopersici race 1 and Fusarium oxysporum f. sp. radicis-lycopersici, respectively from the wilt-infected tomato and brinjal collected from the four districts. Thirty endophytic bacterial isolates were isolated from healthy tomato and brinjal stems were antagonistic against Fusarium oxysporum f. sp. lycopersici and Fusarium solani. Molecular identification revealed that Pseudomonas geniculata strain ICPH-14, Pseudomonas sp. strain SB 904 (E7), Delftia tsuruhatensis strain MTQ 1, Stenotropomonas maltophilia strain ATCC 13637, Stenotropomonas pavanii strain ICB 89, and Bacillus velezensis strain C19 were among the potential endophytic antagonists.

1366. In Vitro and In Vivo Activity of Cefiderocol against Stenotrophomonas maltophilia Clinical Isolates

BackgroundCefiderocol (S-649266, CFDC) is a novel siderophore cephalosporin against Gram-negatives, including carbapenem (CR)-resistant strains. Its spectrum includes both the Enterobacteriaceae but also nonfermenters, including Stenotrophomonas maltophilia—an opportunistic pathogen with intrinsic resistance to carbapenem antibiotics. In this study, in vitro activity and in vivo efficacy of CFDC and comparators against S. maltophilia were determined.MethodsMICs of CFDC and comparators (trimethoprim/sulfamethoxazole (TMP/SMX), minocycline (MINO), tigecycline (TGC), ciprofloxacin (CPFX), cefepime (CFPM), meropenem (MEPM), and colistin (CL)) were determined by broth microdilution method as recommended by CLSI. The MIC against CFDC was determined using iron-depleted cation-adjusted Mueller–Hinton broth. In vivo efficacy of CFDC, CFPM, ceftazidime–avibactam (CAZ/AVI), MEPM, and CL was evaluated using neutropenic murine systemic infection model caused by strain SR21970. The 50% effective doses (ED50s) were calculated by the logit method using the survival number at each dose 7 days after infection.ResultsMIC90 of CFDC and comparators against the 216 clinical isolates from global countries collected in SIDERO-CR 2014/2016 study are shown in the table. CFDC, TMP/SMX, MINO, and TGC showed good activity with MIC90 of 0.5, 0.25/4.75, 1, and 2 µg/mL, respectively. CFDC, MINO, and TGC inhibited growth of all tested strains at ≤1, ≤4, and ≤8 µg/mL although two strains showed resistance to TMP/SMX. MICs of CFPM, CAZ/AVI, MEPM, and CL were ≥32 µg/mL. The ED50 of CFDC against S. maltophilia SR21970 with MIC of 0.125 mg/mL was 1.17 mg/kg/dose. Conversely, MICs of CFPM, CAZ/AVI, MEPM/CS, and CL against SR21970 were 32 μg/mL or higher, and ED50s were >100 mg/kg/dose, showing that CFDC had potent in vivo efficacy against S. maltophilia strain which was resistant to other antibiotics.MIC Range (µg/mL)MIC50 (µg/mL)MIC90 (µg/mL)CFDC≤0.031 to 10.0630.5TMP/SMX≤0.031/≤0.589 to 16/3040.125/2.3750.25/4.75MINO0.063 to 40.251TGC0.125 to 812CPFX0.5 to >32216CFPM2 to >3232>32MEPM0.25 to >32>32>32CL0.125 to >32416ConclusionCFDC showed potent in vitro activity against S. maltophilia, including TMP/SMX-resistant isolates. CFDC also showed potent in vivo efficacy reflecting in vitro activity against S. maltophilia in murine systemic infection model.Disclosures A. Ito, Shionogi & Co., Ltd.: Employee, Salary. M. Ota, Shionogi & Co., Ltd.: Employee, Salary. R. Nakamura, Shionogi & Co., Ltd.: Employee, Salary. M. Tsuji, Shionogi & Co., Ltd.: Employee, Salary. T. Sato, Shionogi & Co., Ltd.: Employee, Salary. Y. Yamano, Shionogi & Co., Ltd.: Employee, Salary.

Molecular characterization of Plant Growth Promoting Rhizobacteria using 16S rRNA sequences in the organic rice field of Sukorejo Village, Central Java, Indonesia

Santosa S, Sutarno, Purwanto E, Suranto, Sajidan. 2018. Molecular characterization of Plant Growth Promoting Rhizobacteria using 16S rRNA sequences in the organic rice field of Sukorejo Village, Central Java, Indonesia. Biodiversitas 19: 2157-2162. Plant Growth Promoting Rhizobacteria (PGPR) are rhizosphere bacteria that can be utilized to increase plant growth and suppress plant diseases. PGPR concentrate on the concept of sustainable agriculture due to their role as biostimulant by synthesizing and regulating the concentration of various phytohormones and as biofertilizers. It is important to determine the original PGPR found in the roots of rice plants. This study aimed to identify PGPR based on 16S rRNA sequences. The bacterial strain was isolated from the rhizospheric soil of IR 64 organic and inorganic rice fields in the region of Sragen District, Central Java, Indonesia. The bacterial isolates were grown on the Luria Bertani (LB) Agar Medium. There were 10 colonies obtained with different morphological variations, nine of those were from the organic rice field. Molecular characterization using 16R rRNA sequences suggested the identity the nine isolates were of Pseudomonas aeruginosa strain RI-98-1, Stenotrophomonas maltophilia strain S431, Bacillus subtilis strain CEB2, Bacillus cereus strain ATCC 14579 clone EA195, S. maltophilia strain 5517, Exiguobacterium acetylicum strain SSA-3, Serratia nematodiphila strain HC4, Bacillus cereus strain ANP221, and Acinetobacter junii strain M. pstv. 21.4 Pseudomonas and Bassilus produce phytohormones (auxins) and convert inorganic phosphate to organic and Stenotropomonas can increase the growth of Acinetobacter and Exigobacterium as phosphate solvents in the soil.

Facile nanorods synthesis of KI:HAp and their structure-morphology, vibrational and bioactivity analyses for biomedical applications

Pure and potassium iodide (KI) doped hydroxyapatite (HAp) nanostructures were prepared through a facile microwave route. Field emission - SEM (FESEM) confirm low dimension nanorods (NRs) morphology of final products. The average dimension of NRs is may be in the range of 10–20 nm. Predominant single segment was approved by XRD and EDX analyses. Lattice constants, crystallite size, density of dislocations, strain and % of crystallinity were determined and the average crystallite size is observed in 9–16 nm range and degree of crystallinity is observed to be high viz. ~ 59% for 30% KI doped HAp. Vibrational studies were done through FT-IR and FT-Raman spectroscopy and confirm the phase of HAp. The catalytic activity of all samples is done in bioremediation of methylene blue using Stenotrophomonas maltophilia strain Kilany_MB. These results suggested that HAp and KI-HAp as a promising nano-catalyst in bioremediation of water from methylene blue.

Degradation of petroleum hydrocarbons and treatment of refinery wastewater under saline condition by a halophilic bacterial consortium enriched from marine environment (Red Sea), Jeddah, Saudi Arabia.

A halophilic bacterial consortium was enriched from Red Sea saline water and sediment samples collected from Abhor, Jeddah, Saudi Arabia. The consortium potentially degraded different low (above 90% for phenanthrene and fluorene) and high (69 ± 1.4 and 56 ± 1.8% at 50 and 100mg/L of pyrene) molecular weight polycyclic aromatic hydrocarbons (PAHs) at different concentrations under saline condition (40g/L NaCl concentration). The cell hydrophobicity (91° ± 1°) and biosurfactant production (30mN/m) confirmed potential bacterial cell interaction with PAHs to facilitate biodegradation process. Co-metabolic study with phenanthrene as co-substrate during pyrene degradation recorded 90% degradation in 12days. The consortium in continuous stirred tank reactor with petroleum refinery wastewater showed complete and 90% degradation of low and high molecular weight PAHs, respectively. The reactor study also revealed 94 ± 1.8% chemical oxygen demand removal by the halophilic consortium under saline condition (40g/L NaCl concentration). The halophilic bacterial strains present in the consortium were identified as Ochrobactrum halosaudis strain CEES1 (KX377976), Stenotrophomonas maltophilia strain CEES2 (KX377977), Achromobacter xylosoxidans strain CEES3 (KX377978) and Mesorhizobium halosaudis strain CEES4 (KX377979). Thus, the promising halophilic consortium was highly recommended to be employed in petroleum saline wastewater treatment process.

Stenotrophomonas maltophilia strain 5DMD: an efficient biosurfactant-producing bacterium for biodegradation of diesel oil and used engine oil

This study relates to the application of newly isolated bacterium, Stenotrophomonas maltophilia strain 5DMD, from the drilled mud of Suleman exploratory oil well no. 1 of Oil and Gas Development Company limited, located at District Khairpur, for biodegradation of two petrochemical hydrocarbons, i.e., diesel oil and used engine oil. The bacterium was identified by routine microbiological techniques followed by the 16S rRNA gene sequencing and homology studies. The experiments were performed using mineral salts medium supplemented with diesel oil and used engine oil as a sole carbon and an energy source under specified culture conditions (35 °C, 160 rpm, 24 days). The hydrocarbon biodegradation rates were estimated in terms of % removal using UV–Vis spectrophotometer, while characteristic spectral changes in both hydrocarbons were confirmed through Attenuated Total Reflectance-Fourier Transform Infrared spectrometry. Consequently, significant degradation rates of 88.5 and 71.8% for were achieved during the experiment. Moreover, the bacterium has also displayed excellent potential for the production of biosurfactants (oil displacement assay = > 6 mm; surface tension = 33.9 and 34.4 m N m−1) and lipase enzyme (Lipolytic zone = 1.8 ± 0.1 cm and 2.2 ± 0.3 cm). Fourier transform infrared spectrometry analyses exhibited substantial changes in % transmittance in the frequency range for characteristic of functional groups of aliphatic (1000–600 and 3000–2800 cm−1) and aromatic (1500–1300 and 1055–1000 cm−1) hydrocarbons in diesel oil and used engine oil, confirming the biodegradation. Therefore, S. maltophilia strain 5DMD could be exploited further for future environmental applications and biosynthesis of surfactants or enzymes.

Purification and characterization of Stenotrophomonas maltophilia-derived l-amino acid ester hydrolase for synthesizing dipeptide, isoleucyl-tryptophan

In the present study, we purified α-amino acid ester hydrolase (AEH) from cell-free extracts of the Stenotrophomonas maltophilia strain HS1. The approximately 70-kDa AEH from S. maltophilia HS1 (SmAEH) was homogeneous in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analyses, and was present as a tetramer in gel-filtration experiments. The activity of the SmAEH enzyme was then determined by monitoring the synthesis of the antihypertensive agent dipeptide isoleucyl-tryptophan (Ile-Trp) from isoleucyl methyl ester (Ile-OMe) and tryptophan (Trp). In these experiments, SmAEH had wide substrate specificity for acyl donors, such as Gly-OMe, β-Ala-OMe, Pro-OMe and Trp-OMe and Ile-OMe, and maximal activity were observed under conditions of pH 9.0 and 30°C. SmAEH also showed the greatest stability at pH 9.0, whereas its activity was reduced by 40% after 10-min incubation at approximately 50°C. In subsequent activity assays in the presence of various metal ions, Ag+ strongly inhibited enzyme activity. Finally, SmAEH activity was completely inhibited by phenylmethanesulfonyl fluoride (PMSF), suggesting that the protein is a serine protease.