Strains ofP Research Articles

Pharmacodynamics of Aerosolized Fosfomycin and Amikacin against Resistant Clinical Isolates of Pseudomonas aeruginosa and Klebsiella pneumoniae in a Hollow-Fiber Infection Model: Experimental Basis for Combination Therapy.

ABSTRACTThere has been a resurgence of interest in aerosolization of antibiotics for treatment of patients with severe pneumonia caused by multidrug-resistant pathogens. A combination formulation of amikacin-fosfomycin is currently undergoing clinical testing although the exposure-response relationships of these drugs have not been fully characterized. The aim of this study was to describe the individual and combined antibacterial effects of simulated epithelial lining fluid exposures of aerosolized amikacin and fosfomycin against resistant clinical isolates of Pseudomonas aeruginosa (MICs of 16 mg/liter and 64 mg/liter) and Klebsiella pneumoniae (MICs of 2 mg/liter and 64 mg/liter) using a dynamic hollow-fiber infection model over 7 days. Targeted peak concentrations of 300 mg/liter amikacin and/or 1,200 mg/liter fosfomycin as a 12-hourly dosing regimens were used. Quantitative cultures were performed to describe changes in concentrations of the total and resistant bacterial populations. The targeted starting inoculum was 108 CFU/ml for both strains. We observed that neither amikacin nor fosfomycin monotherapy was bactericidal against P. aeruginosa while both were associated with rapid amplification of resistant P. aeruginosa strains (about 108 to 109 CFU/ml within 24 to 48 h). For K. pneumoniae, amikacin but not fosfomycin was bactericidal. When both drugs were combined, a rapid killing was observed for P. aeruginosa and K. pneumoniae (6-log kill within 24 h). Furthermore, the combination of amikacin and fosfomycin effectively suppressed growth of resistant strains of P. aeruginosa and K. pneumoniae. In conclusion, the combination of amikacin and fosfomycin was effective at maximizing bacterial killing and suppressing emergence of resistance against these clinical isolates.

LasR Variant Cystic Fibrosis Isolates Reveal an Adaptable Quorum-Sensing Hierarchy in Pseudomonas aeruginosa.

ABSTRACTChronic Pseudomonas aeruginosa infections cause significant morbidity in patients with cystic fibrosis (CF). Over years to decades, P. aeruginosa adapts genetically as it establishes chronic lung infections. Nonsynonymous mutations in lasR, the quorum-sensing (QS) master regulator, are common in CF. In laboratory strains of P. aeruginosa, LasR activates transcription of dozens of genes, including that for another QS regulator, RhlR. Despite the frequency with which lasR coding variants have been reported to occur in P. aeruginosa CF isolates, little is known about their consequences for QS. We sequenced lasR from 2,583 P. aeruginosa CF isolates. The lasR sequences of 580 isolates (22%) coded for polypeptides that differed from the conserved LasR polypeptides of well-studied laboratory strains. This collection included 173 unique lasR coding variants, 116 of which were either missense or nonsense mutations. We studied 31 of these variants. About one-sixth of the variant LasR proteins were functional, including 3 with nonsense mutations, and in some LasR-null isolates, genes that are LasR dependent in laboratory strains were nonetheless expressed. Furthermore, about half of the LasR-null isolates retained RhlR activity. Therefore, in some CF isolates the QS hierarchy is altered such that RhlR quorum sensing is independent of LasR regulation. Our analysis challenges the view that QS-silent P. aeruginosa is selected during the course of a chronic CF lung infection. Rather, some lasR sequence variants retain functionality, and many employ an alternate QS strategy involving RhlR.

Genome Sequence of Pseudomonas chlororaphis Strain 189.

Pseudomonas chlororaphis strain 189 is a potent inhibitor of the growth of the potato pathogen Phytophthora infestans. We determined the complete, finished sequence of the 6.8-Mbp genome of this strain, consisting of a single contiguous molecule. Strain 189 is closely related to previously sequenced strains of P. chlororaphis.

High-Quality Draft Genome Sequences of Pantoea agglomerans Isolates Exhibiting Antagonistic Interactions with Wheat Seed-Associated Fungi.

Pantoea agglomerans isolates 3 and 4 were retrieved from the bacterial community associated with wheat seeds. These isolates differ in their pattern of growth antagonism toward Alternaria species. A comparison of the genome sequences of these two isolates revealed a high sequence identity with previously sequenced strains of P. agglomerans.

Improved High-Quality Draft Genome Sequence of Pseudomonas fluorescens KENGFT3

Pseudomonas sp. strain KENGFT3 inhibits the growth of Phytophthora infestans and is a potentially useful biopesticide for plant diseases, including potato late blight. We sequenced the 6.2-Mbp genome of this strain and assembled it into a single scaffold with 9 contigs. KENGFT3 is related to previously sequenced strains of P. fluorescens.

Draft Genome Sequence of Pseudomonas syringae pv. syringae ALF3 Isolated from Alfalfa.

We report here the annotated draft genome sequence of Pseudomonas syringae pv. syringae strain ALF3, isolated in Wyoming. A comparison of this genome sequence with those of closely related strains of P. syringae adapted to other hosts will facilitate research into interactions between this pathogen and alfalfa.

Strain-Level Differences in Porphyrin Production and Regulation in Propionibacterium acnes Elucidate Disease Associations.

Propionibacterium acnes is an important skin commensal, but it is also considered a pathogenic factor in several diseases including acne vulgaris, the most common skin disease. While previous studies have revealed P.acnes strain-level differences in health and disease associations, the underlying molecular mechanisms remain unknown. Recently, we demonstrated that vitamin B12 supplementation increases P.acnes production of porphyrins, a group of proinflammatory metabolites important in acne development (D. Kang, B. Shi, M. C. Erfe, N. Craft, and H. Li, Sci. Transl. Med. 7:293ra103, 2015, doi:10.1126/scitranslmed.aab2009). In this study, we compared the porphyrin production and regulation of multiple P.acnes strains. We revealed that acne-associated type IA-2 strains inherently produced significantly higher levels of porphyrins, which were further enhanced by vitamin B12 supplementation. On the other hand, health-associated type II strains produced low levels of porphyrins and did not respond to vitamin B12. Using a small-molecule substrate and inhibitor, we demonstrated that porphyrin biosynthesis was modulated at the metabolic level. We identified a repressor gene (deoR) of porphyrin biosynthesis that was carried in all health-associated type II strains, but not in acne-associated type IA-2 strains. The expression of deoR suggests additional regulation of porphyrin production at the transcriptional level in health-associated strains. Our findings provide one potential molecular mechanism for the different contributions of P.acnes strains to skin health and disease and support the role of vitamin B12 in acne pathogenesis. Our study emphasizes the importance of understanding the role of the commensal microbial community in health and disease at the strain level and suggests potential utility of health-associated P.acnes strains in acne treatment. IMPORTANCE Propionibacteriumacnes is a dominant bacterium residing on skin, and it has been thought to play a causal role in several diseases including acne, a common skin disease affecting more than 80% of people worldwide. While specific strains of P.acnes have been associated with either disease or healthy skin, the mechanisms remain unclear. Recently, we showed that vitamin B12 supplementation increased porphyrin production in P.acnes, leading to acne development (D. Kang, B. Shi, M. C. Erfe, N. Craft, and H. Li, Sci. Transl. Med. 7:293ra103, 2015, doi:10.1126/scitranslmed.aab2009). Here, we reveal that the levels of porphyrin production and vitamin B12 regulation are different between acne- and health-associated strains, suggesting a potential molecular mechanism for disease-associated strains in acne pathogenesis and for health-associated strains in skin health. This study highlights the importance of understanding the strain-level differences of the human microbiota in disease pathogenesis. Our findings also suggest the porphyrin biosynthesis pathway as a candidate drug target and use of health-associated strains as potential probiotics in novel acne therapeutics.

Pharmacodynamics of Ceftolozane plus Tazobactam Studied in an In Vitro Pharmacokinetic Model of Infection.

Ceftolozane plus tazobactam is an antipseudomonal cephalosporin combined with tazobactam, an established beta-lactamase inhibitor, and has in vitro potency against a range of clinically important β-lactamase-producing bacteria, including most extended-spectrum-β-lactamase (ESBL)-positive Enterobacteriaceae. The pharmacodynamics of β-lactam-β-lactamase inhibitor combinations presents a number of theoretical and practical challenges, including modeling different half-lives of the compounds. In this study, we studied the pharmacodynamics of ceftolozane plus tazobactam against Escherichia coli and Pseudomonas aeruginosa using an in vitro pharmacokinetic model of infection. Five strains of E. coli, including three clinical strains plus two CTX-M-15 (one high and one moderate) producers, and five strains of P. aeruginosa, including two with OprD overexpression and AmpC β-lactamases, were employed. Ceftolozane MICs (E. coli, 0.12 to 0.25 mg/liter, and P. aeruginosa, 0.38 to 8 mg/liter) were determined in the presence of 4 mg/liter tazobactam. Dose ranging of ceftolozane (percentage of time in which the free-drug concentration exceeds the MIC [fT>MIC], 0 to 100%) plus tazobactam (human pharmacokinetics) was simulated every 8 hours, with half-lives (t1/2) of 2.5 and 1 h, respectively. Ceftolozane and tazobactam concentrations were confirmed by high-performance liquid chromatography (HPLC). The ceftolozane-plus-tazobactam fT>MIC values at 24 h for a static effect and a 1-log and 2-log drop in initial inoculum for E. coli were 27.8% ± 5.6%, 33.0% ± 5.6%, and 39.6% ± 8.5%, respectively. CTX-M-15 production did not affect the 24-h fT>MIC for E. coli strains. The ceftolozane-plus-tazobactam fT>MIC values for a 24-h static effect and a 1-log and 2-log drop for P. aeruginosa were 24.9% ± 3.0%, 26.6% ± 3.9%, and 31.2% ± 3.6%. Despite a wide range of absolute MICs, the killing remained predictable as long as the MICs were normalized to the corresponding fT>MIC. Emergence of resistance on 4× MIC plates and 8× MIC plates occurred maximally at an fT>MIC of 10 to 30% and increased as time of exposure increased. The fT>MIC for a static effect for ceftolozane plus tazobactam is less than that observed with other cephalosporins against E. coli and P. aeruginosa and is more similar to the fT>MIC reported for carbapenems.

Origin of the Outbreak in France of Pseudomonas syringae pv. actinidiae Biovar 3, the Causal Agent of Bacterial Canker of Kiwifruit, Revealed by a Multilocus Variable-Number Tandem-Repeat Analysis.

The first outbreaks of bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae biovar 3 were detected in France in 2010. P. syringae pv. actinidiae causes leaf spots, dieback, and canker that sometimes lead to the death of the vine. P. syringae pv. actinidifoliorum, which is pathogenic on kiwi as well, causes only leaf spots. In order to conduct an epidemiological study to track the spread of the epidemics of these two pathogens in France, we developed a multilocus variable-number tandem-repeat (VNTR) analysis (MLVA). MLVA was conducted on 340 strains of P. syringae pv. actinidiae biovar 3 isolated in Chile, China, France, Italy, and New Zealand and on 39 strains of P. syringae pv. actinidifoliorum isolated in Australia, France, and New Zealand. Eleven polymorphic VNTR loci were identified in the genomes of P. syringae pv. actinidiae biovar 3 ICMP 18744 and of P. syringae pv. actinidifoliorum ICMP 18807. MLVA enabled the structuring of P. syringae pv. actinidiae biovar 3 and P. syringae pv. actinidifoliorum strains in 55 and 16 haplotypes, respectively. MLVA and discriminant analysis of principal components revealed that strains isolated in Chile, China, and New Zealand are genetically distinct from P. syringae pv. actinidiae strains isolated in France and in Italy, which appear to be closely related at the genetic level. In contrast, no structuring was observed for P. syringae pv. actinidifoliorum. We developed an MLVA scheme to explore the diversity within P. syringae pv. actinidiae biovar 3 and to trace the dispersal routes of epidemic P. syringae pv. actinidiae biovar 3 in Europe. We suggest using this MLVA scheme to trace the dispersal routes of P. syringae pv. actinidiae at a global level.

Functional Analysis of Porphyromonas gingivalis W83 CRISPR-Cas Systems.

The CRISPR-Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated genes) system provides prokaryotic cells with an adaptive and heritable immune response to foreign genetic elements, such as viruses, plasmids, and transposons. It is present in the majority of Archaea and almost half of species of Bacteria. Porphyromonas gingivalis is an important human pathogen that has been proven to be an etiological agent of periodontitis and has been linked to systemic conditions, such as rheumatoid arthritis and cardiovascular disease. At least 95% of clinical strains of P. gingivalis carry CRISPR arrays, suggesting that these arrays play an important function in vivo. Here we show that all four CRISPR arrays present in the P. gingivalis W83 genome are transcribed. For one of the arrays, we demonstrate in vivo activity against double-stranded DNA constructs containing protospacer sequences accompanied at the 3' end by an NGG protospacer-adjacent motif (PAM). Most of the 44 spacers present in the genome of P. gingivalis W83 share no significant similarity with any known sequences, although 4 spacers are similar to sequences from bacteria found in the oral cavity and the gastrointestinal tract. Four spacers match genomic sequences of the host; however, none of these is flanked at its 3' terminus by the appropriate PAM element. The CRISPR-Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated genes) system is a unique system that provides prokaryotic cells with an adaptive and heritable immunity. In this report, we show that the CRISPR-Cas system of P. gingivalis, an important human pathogen associated with periodontitis and possibly also other conditions, such as rheumatoid arthritis and cardiovascular disease, is active and provides protection from foreign genetic elements. Importantly, the data presented here may be useful for better understanding the communication between cells in larger bacterial communities and, consequently, the process of disease development and progression.

In vitro antimalarial activity of novel semisynthetic nocathiacin I antibiotics.

Presently, the arsenal of antimalarial drugs is limited and needs to be replenished. We evaluated the potential antimalarial activity of two water-soluble derivatives of nocathiacin (BMS461996 and BMS411886) against the asexual blood stages of Plasmodium falciparum. Nocathiacins are a thiazolyl peptide group of antibiotics, are structurally related to thiostrepton, have potent activity against a wide spectrum of multidrug-resistant Gram-positive bacteria, and inhibit protein synthesis. The in vitro growth inhibition assay was done using three laboratory strains of P. falciparum displaying various levels of chloroquine (CQ) susceptibility. Our results indicate that BMS461996 has potent antimalarial activity and inhibits parasite growth with mean 50% inhibitory concentrations (IC50s) of 51.55 nM for P. falciparum 3D7 (CQ susceptible), 85.67 nM for P. falciparum Dd2 (accelerated resistance to multiple drugs [ARMD]), and 99.44 nM for P. falciparum K1 (resistant to CQ, pyrimethamine, and sulfadoxine). Similar results at approximately 7-fold higher IC50s were obtained with BMS411886 than with BMS461996. We also tested the effect of BMS491996 on gametocytes; our results show that at a 20-fold excess of the mean IC50, gametocytes were deformed with a pyknotic nucleus and growth of stage I to IV gametocytes was arrested. This preliminary study shows a significant potential for nocathiacin analogues to be developed as antimalarial drug candidates and to warrant further investigation.

Psychrobacter ciconiae sp. nov., isolated from white storks (Ciconia ciconia).

Five beige bacterial strains (176/10(T), 178/10, 182/10, 185/7 and 193/8) were isolated from white storks in Poland and found to share identical 16S rRNA gene sequences; they were also investigated in a polyphasic taxonomic study. The cells of all isolates were rod-shaped and Gram-stain-negative. A comparison of the 16S rRNA gene sequences of these organisms with the sequences of the type strains of the most closely related species of the genus Psychrobacter showed highest sequence similarities to the type strains of Psychrobacter pulmonis and Psychrobacter faecalis (both 97.1 %). The 16S rRNA gene sequence similarities to all other species of the genus Psychrobacter were below 96.3 %. All five isolates showed an identical profile of physiological reactions and almost identical fatty acid profiles consisting of mainly C18 : 1ω9c, but also C12 : 0 3-OH as a characteristic hydroxylated fatty acid. A quinone system with mainly ubiquinone Q-8 was detected and the polar lipid profile of the type strain, 176/10(T), was mainly composed of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine and diphosphatidylglycerol, plus some hitherto uncharacterized phospholipids and one aminolipid. The major polyamines were spermidine and putrescine. DNA-DNA hybridizations between 176/10(T) and the type strains of P. pulmonis and P. faecialis resulted in relatedness values below 70 %. These results indicate that the strains represent a novel species, for which the name Psychrobacter ciconiae sp. nov. (type strain 176/10(T) = CIP 110777(T) = LMG 28175(T) = CCM 8519(T)) is proposed.

Enzymatic characterization and in vivo function of five terminal oxidases in Pseudomonas aeruginosa.

The ubiquitous opportunistic pathogen Pseudomonas aeruginosa has five aerobic terminal oxidases: bo(3)-type quinol oxidase (Cyo), cyanide-insensitive oxidase (CIO), aa3-type cytochrome c oxidase (aa3), and two cbb(3)-type cytochrome c oxidases (cbb(3)-1and cbb(3)-2). These terminal oxidases are differentially regulated under various growth conditions and are thought to contribute to the survival of this microorganism in a wide variety of environmental niches. Here, we constructed multiple mutant strains of P. aeruginosa that express only one aerobic terminal oxidase to investigate the enzymatic characteristics and in vivo function of each enzyme. The Km values of Cyo, CIO, and aa3 for oxygen were similar and were 1 order of magnitude higher than those of cbb(3)-1 and cbb(3)-2, indicating that Cyo, CIO, and aa3 are low-affinity enzymes and that cbb(3)-1 and cbb(3)-2 are high-affinity enzymes. Although cbb(3)-1 and cbb(3)-2 exhibited different expression patterns in response to oxygen concentration, they had similar Km values for oxygen. Both cbb(3)-1 and cbb(3)-2 utilized cytochrome c4 as the main electron donor under normal growth conditions. The electron transport chains terminated by cbb(3)-1 and cbb(3)-2 generate a proton gradient across the cell membrane with similar efficiencies. The electron transport chain of aa3 had the highest proton translocation efficiency, whereas that of CIO had the lowest efficiency. The enzymatic properties of the terminal oxidases reported here are partially in agreement with their regulatory patterns and may explain the environmental adaptability and versatility of P. aeruginosa.

Negative regulation of germination-arrest factor production in Pseudomonas fluorescens WH6 by a putative extracytoplasmic function sigma factor.

Pseudomonas fluorescens WH6 secretes a germination-arrest factor (GAF) that we have identified previously as 4-formylaminooxyvinylglycine. GAF irreversibly inhibits germination of the seeds of numerous grassy weeds and selectively inhibits growth of the bacterial plant pathogen Erwinia amylovora. WH6-3, a mutant that has lost the ability to produce GAF, contains a Tn5 insertion in prtR, a gene that has been described previously in some strains of P. fluorescens as encoding a transmembrane regulator. As in these other pseudomonads, in WH6, prtR occurs immediately downstream of prtI, which encodes a protein homologous to extracytoplasmic function (ECF) sigma factors. These two genes have been proposed to function as a dicistronic operon. In this study, we demonstrated that deletion of prtI in WT WH6 had no effect on GAF production. However, deletion of prtI in the WH6-3 mutant overcame the effects of the Tn5 insertion in prtR and restored GAF production in the resulting double mutant. Complementation of the double prtIR mutant with prtI suppressed GAF production. This overall pattern of prtIR regulation was also observed for the activity of an AprX protease. Furthermore, reverse transcription quantitative real-time PCR analysis demonstrated that alterations in GAF production were mirrored by changes in the transcription of two putative GAF biosynthetic genes. Thus, we concluded that PrtI exerted a negative regulatory effect on GAF production, although the mechanism has not yet been determined. In addition, evidence was obtained that the transcription of prtI and prtR in WH6 may be more complex than predicted by existing models.

Boseongicola aestuarii gen. nov., sp. nov., isolated from a tidal flat sediment

A Gram-stain-negative, aerobic, non-motile and pleomorphic (coccoid, ovoid or rod-shaped) bacterial strain, BS-W15(T), isolated from a tidal flat sediment at Boseong in South Korea, was characterized taxonomically. Strain BS-W15(T) grew optimally at 25 °C, at pH 7.0-8.0 and in the presence of approximately 2.0% (w/v) NaCl. Neighbour-joining and maximum-likelihood phylogenetic trees, based on 16S rRNA gene sequences, revealed that strain BS-W15(T) joined the cluster comprising the type strains of Profundibacterium mesophilum, Hwanghaeicola aestuarii, M. pelagius and M. salinus, showing 93.5-96.4% sequence similarities. Strain BS-W15(T) contained Q-10 as the predominant ubiquinone and C(18 : 1)ω7c as the predominant fatty acid. The polar lipid profile of strain BS-W15(T) contained phosphatidylcholine and phosphatidylglycerol as major components, differentiating it from those of the type strains of P. mesophilum, H. aestuarii, M. pelagius and M. salinus. The DNA G+C content of strain BS-W15(T) was 58.7 mol%. The differential phenotypic properties, together with the phylogenetic and chemotaxonomic data, demonstrate that strain BS-W15(T) is distinct from type strains of P. mesophilum, H. aestuarii, M. pelagius and M. salinus. On the basis of the data presented, strain BS-W15(T) is considered to represent a novel genus and species, for which the name Boseongicola aestuarii gen. nov., sp. nov. is proposed. The type strain is BS-W15(T) ( = KCTC 32576(T) = CECT 8489(T)).

Antibiotic Resistance Pattern and Evaluation of Metallo-Beta Lactamase Genes Including bla- IMP and bla- VIM Types in Pseudomonas aeruginosa Isolated from Patients in Tehran Hospitals.

Beta-lactamase producing strains of Pseudomonas aeruginosa are important etiological agents of hospital infections. Carbapenems are among the most effective antibiotics used against Pseudomonas infections, but they can be rendered infective by group B β-lactamase, commonly called metallo-beta lactamase. In this study, the antimicrobial sensitivity patterns of P. aeruginosa strains isolated from 9 different hospitals in Tehran, Iran, as well as the prevalence of MBLs genes (bla-VIM and bla-IMP) were determined. A total of 212 strains of P. aeruginosa recovered from patients in hospitals in Tehran were confirmed by both biochemical methods and PCR. Their antimicrobial sensitivity patterns were determined by Kirby-Bauer disk diffusion method. Following MIC determination, imipenem resistant strains were selected by DDST method which was followed by PCR tests for determination of MBLs genes: bla-IMP and bla-VIM. The results indicated that, in the DDST phenotypic method, among the 100 imipenem resistant isolates, 75 strains were MBLs positive. The PCR test indicated that 70 strains (33%) carried bla-VIM gene and 20 strains (9%) harbored bla-IMP. The results indicated that the extent of antibiotic resistance among Pseudomonas aeruginosa is on the rise. This may be due to production of MBLs enzymes. Therefore, determination of antibiotic sensitivity patterns and MBLs production by these bacteria, can be important in control of clinical Pseudomonas infection.

Molecular divergence and species delimitation of the cultivated oyster mushrooms: integration of IGS1 and ITS.

Identification of edible mushrooms particularly Pleurotus genus has been restricted due to various obstacles. The present study attempted to use the combination of two variable regions of IGS1 and ITS for classifying the economically cultivated Pleurotus species. Integration of the two regions proved a high ability that not only could clearly distinguish the species but also served sufficient intraspecies variation. Phylogenetic tree (IGS1 + ITS) showed seven distinct clades, each clade belonging to a separate species group. Moreover, the species differentiation was tested by AMOVA and the results were reconfirmed by presenting appropriate amounts of divergence (91.82% among and 8.18% within the species). In spite of achieving a proper classification of species by combination of IGS1 and ITS sequences, the phylogenetic tree showed the misclassification of the species of P. nebrodensis and P. eryngii var. ferulae with other strains of P. eryngii. However, the constructed median joining (MJ) network could not only differentiate between these species but also offer a profound perception of the species' evolutionary process. Eventually, due to the sufficient variation among and within species, distinct sequences, simple amplification, and location between ideal conserved ribosomal genes, the integration of IGS1 and ITS sequences is recommended as a desirable DNA barcode.

Effect of Pseudomonas putida on growth and anthocyanin pigment in two poinsettia (Euphorbia pulcherrima) cultivars.

Pseudomonas putida is plant growth promoting rhizobacteria (PGPR) that have the capacity to improve growth in plants. The purpose of this study was to determine growth and anthocyanin pigmentation of the bracts in two poinsettia Euphorbia pulcherrima cultivars (Prestige and Sonora Marble) using three strains of P. putida, as well as a mixture of the three (MIX). Comparison with the control group indicated for the most part that Prestige grew better than the Sonora Marble cultivars with the PGPR strains. Prestige with the MIX strain grew better compared to control for the number of cyathia (83 versus 70.4), volume of roots (45 versus 35 cm3), number of leaves (78 versus 58), and area of leaf (1,788 versus 1,331 cm2), except for the number of flowers (8.8 versus 11.6). To the naked eye, coloration of plants appeared identical in color compared to the control group. For all plants with P. putida strains, there was less anthocyanin pigment, but biomass was always greater with PGPR strains. Nevertheless, to the naked eye, the coloration of the plants appeared identical in color compared to the control group. This is the first study reporting the positive effects of P. putida rhizobacteria treatments on growth of poinsettia cultivars.

Global genome comparative analysis reveals insights of resistome and life-style adaptation of Pseudomonas putida strain T2-2 in oral cavity.

Most Pseudomonas putida strains are environmental microorganisms exhibiting a wide range of metabolic capability but certain strains have been reported as rare opportunistic pathogens and some emerged as multidrug resistant P. putida. This study aimed to assess the drug resistance profile of, via whole genome analysis, P. putida strain T2-2 isolated from oral cavity. At the same time, we also compared the nonenvironmental strain with environmentally isolated P. putida. In silico comparative genome analysis with available reference strains of P. putida shows that T2-2 has lesser gene counts on carbohydrate and aromatic compounds metabolisms, which suggested its little versatility. The detection of its edd gene also suggested T2-2's catabolism of glucose via ED pathway instead of EMP pathway. On the other hand, its drug resistance profile was observed via in silico gene prediction and most of the genes found were in agreement with drug-susceptibility testing in laboratory by automated VITEK 2. In addition, the finding of putative genes of multidrug resistance efflux pump and ATP-binding cassette transporters in this strain suggests a multidrug resistant phenotype. In summary, it is believed that multiple metabolic characteristics and drug resistance in P. putida strain T2-2 helped in its survival in human oral cavity.

Fitness costs associated with field-evolved resistance to chlorantraniliprole inPlutella xylostella(Lepidoptera: Plutellidae)

Plutella xylostella (L.) is the most important pest of Brassicaceae worldwide, with a recent estimate of US$ 4-5 billion expenditure for the control of this insect. A case of very high resistance of this pest to chlorantraniliprole was recently associated with reduced efficacy in a Brazilian field of Brassica spp. Although diamide resistance has been characterized, the fitness of insects due to such resistance has yet to be examined. Therefore, in this study, biological parameters were assessed in both susceptible and resistant strains of P. xylostella subjected to sublethal chlorantraniliprole concentrations. The field strain showed high resistance to chlorantraniliprole (RR50=27,793-fold), although resistance rapidly decreased in the first generations, showing instability. The exposure of susceptible and resistant larvae to their respective LC1, LC10, and LC25 values led to an increased duration of the larval and pupae phases and reduced weight in both strains; however, no significant differences in pupal viability across the treatments were observed. The resistant insects presented significantly lower larval weight and fecundity and higher larval and pupal periods, hatchability, and male longevity when not exposed to chlorantraniliprole, suggesting a fitness cost associated with resistance. In addition, resistant females showed a significantly higher egg-laying period and longevity at LC25, whereas the males lived longer at LC1. Chlorantraniliprole negatively impacted the biological parameters of both strains tested, although these effects were more relevant to the resistant insects. Resistant P. xylostella showed negative and positive biological trade-offs when compared with the susceptible individuals in both the absence and presence of chlorantraniliprole. Despite the important role that these trade-offs may play in the evolution of resistance to chlorantraniliprole, practical applications still depend on such information as the dominance of fitness costs and resistance.