Nitrogen removal characteristics of novel bacterium Klebsiella sp. TSH15 by assimilatory/dissimilatory nitrate reduction and ammonia assimilation.

A novel strain with heterotrophic nitrification and aerobic denitrification was screened and identified as Klebsiella sp. TSH15 by 16S rRNA. The results demonstrated that the ammonia-N and nitrate-N removal rates were 2.99 mg/L/h and 2.53 mg/L/h under optimal conditions, respectively. The analysis of the whole genome indicated that strain TSH15 contained the key genes involved in assimilatory/dissimilatory nitrate reduction and ammonia assimilation, including nas, nar, nir, nor, glnA, gltB, gdhA, and amt. The relative expression levels of key nitrogen removal genes were further detected by RT-qPCR. The results indicated that the N metabolic pathways of strain TSH15 were the conversion of nitrate or nitrite to ammonia by assimilatory/dissimilatory nitrate reduction (NO3-→NO2-→NH4+) and further conversion of ammonia to glutamate (NH4+-N â†’ Glutamate) by ammonia assimilation. These results indicated that the strain TSH15 had the potential to be applied to practical sewage treatment in the future.

Enhanced rice plant (BRRI-28) growth at lower doses of urea caused by diazinon mineralizing endophytic bacterial consortia and explorations of relevant regulatory genes in a Klebsiella sp. strain HSTU-F2D4R.

Endophytic biostimulant with pesticide bioremediation activities may reduce agrochemicals application in rice cultivation. The present study evaluates diazinon-degrading endophytic bacteria, isolated from rice plants grown in the fields with pesticide amalgamation, leading to increased productivity in high-yielding rice plants. These endophytes showed capabilities of decomposing diazinon, confirmed by FT-IR spectra analysis. Growth promoting activities of these endophytes can be attributed to their abilities to produce an increased level of IAA content and to demonstrate high level ACC-deaminase activities. Furthermore, these endophytes demonstrated enhanced level of extracellular cellulase, xylanase, amylase, protease and lignin degrading activities. Five genera including Enterobacter, Pantoea, Shigella, Acinetobacter, and Serratia, are represented only by the leaves, while four genera such as Enterobacter, Escherichia, Kosakonia, and Pseudomonas are represented only by the shoots. Five genera including, Klebsiella, Enterobacter, Pseudomonas, Burkholderia, and Bacillus are represented only by the roots of rice plants. All these strains demonstrated cell wall hydrolytic enzyme activities, except pectinase. All treatments, either individual strains or consortia of strains, enhanced rice plant growth at germination, seedling, vegetative and reproductive stages. Among four (I-IV) consortia, consortium-III generated the maximum rice yield under 70% lower doses of urea compared to that of control (treated with only fertilizer). The decoded genome of Klebsiella sp. HSTU-F2D4R revealed nif-cluster, chemotaxis, phosphates, biofilm formation, and organophosphorus insecticide-degrading genes. Sufficient insecticide-degrading proteins belonging to strain HSTU-F2D4R had interacted with diazinon, confirmed in molecular docking and formed potential catalytic triads, suggesting the strains have bioremediation potential with biofertilizer applications in rice cultivation.

Odor-mediated response of gravid Aedes aegypti to mosquito-associated symbiotic bacteria.

Complex oviposition decisions allow gravid Aedes aegypti mosquitoes to select suitable sites for egg-laying to increase the probability that their progeny will thrive. The bacterial communities present in larval niches influence mosquito oviposition behavior, and gravid mosquitoes transmit key microbial associates to breeding sites during oviposition. Our study evaluated whether symbiotic Klebsiella sp., which are strongly associated with mosquitoes, emit volatiles that affect mosquito oviposition decisions. Dual-choice behavioral assays demonstrated that volatile organic compounds emitted by Klebsiella sp. induce a preference in oviposition decisions by Ae. aegypti. Bacterial headspace volatiles were sampled by solid-phase microextraction, and subsequent combined gas chromatography and electroantennogram detection analysis, revealed that the antennae of gravid females detect two compounds present in the Klebsiella sp. headspace. These compounds were identified by gas chromatography and mass spectrometry as 2-ethyl hexanol and 2,4-di­tert-butylphenol. The binary blend of these compounds elicited a dose-dependent egg-laying preference by gravid mosquitoes. We propose that bacterial symbionts, which are associated with gravid mosquitoes and may be transferred to aquatic habitats during egg-laying, together with their volatiles act as oviposition cues indicating the suitability of active breeding sites to conspecific females.

The capability of chloramphenicol biotransformation of Klebsiella sp. YB1 under cadmium stress and its genome analysis.

Co-contamination by antibiotics and heavy metal is common in the environment, however, there is scarce information about antibiotics biodegradation under heavy metals stress. In this study, Klebsiella sp. Strain YB1 was isolated which is capable of biodegrading chloramphenicol (CAP) with a biodegradation efficiency of 22.41% at an initial CAP of 10 mg L-1 within 2 days. CAP biodegradation which fitted well with the first-order kinetics. YB1 still degrades CAP under Cd stress, however 10 mg L-1 Cd inhibited CAP biodegradation by 15.1%. Biotransformation pathways remained the same under Cd stress, but two new products (Cmpd 19 and Cmpd 20) were identified. Five parallel metabolism pathways of CAP were proposed with/without Cd stress, including one novel pathway (pathway 5) that has not been reported before. In pathway 5, the initial reaction was oxidation of CAP by disruption of C-C bond at the side chain of C1 and C2 with the formation of 4-nitrobenzyl alcohol and CY7, then these intermediates were oxidized into p-nitrobenzoic acid and CY1, respectively. CAP acetyltransferase and nitroreductase and 2,3/4,5-dioxygenase may play an important role in CAP biodegradation through genome analysis and prediction. This study deepens our understanding of mechanism of antibiotic degradation under heavy metal stress in the environment.

Plant growth promoting activities and effect of fermented panchagavya isolate Klebsiella sp. PG-64 on Vigna radiata.

A natural bacterial isolate from fermented panchagavya named as PG-64, exhibits multiple plant growth-promoting traits. This Gram-negative bacteria was identified as Klebsiella sp. PG-64 by 16S rRNA gene sequencing. The Klebsiella sp. PG-64 has shown production of indole acetic acid (106.0 µg/ml), gibberellic acid (20.0 µg/ml), ammonia (7.12 µmol/ml), exopolysaccharide (2.04% w/v) and phosphate solubilization (106.0 µg/ml). It produced 437 µg/ml IAA with 0.75% (w/v) L-tryptophan supplementation and was increased to 575 µg/ml in a laboratory-scale fermenter. The PG-64 has shown tolerance to abiotic stress conditions like pH (5.0-12.0), temperature (28-46 °C), salt (0.5-10.0% w/v NaCl) and osmotic resistance (1-10% w/v PEG-6000). The PG-64 also produced 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (0.3 ng α-ketobutyrate/mg protein/h) indicating its potential for drought tolerance. Owing to its diverse properties, the effect of Klebsiella sp. PG-64 on Vigna radiata (Mung bean) was examined. The seeds treated with PG-64 culture showed 92% germination with a good seedling vigour index (202). In the pot study, Vigna radiata growth showed 2.23, 1.55, 2.00, 1.65, 1.73, 1.88, 5.00, 5.00, 1.57 times increase in primary root length, dry root weight, root hair numbers, leaf width, leaf numbers, leaf area, fruits number, flower number and chlorophyll content, respectively after 75 days. The application of Klebsiella sp. PG-64 culture resulted in substantial growth enhancement of Vigna radiata. The Klebsiella sp. PG-64 has multiple plant growth-promoting properties along with capabilities to tolerate abiotic stresses, making it a promising liquid biofertilizer contender for various crops.

Genome mining discovery of hydrogen production pathway of Klebsiella sp. WL1316 fermenting cotton stalk hydrolysate

Genome sequencing was used to identify key genes for the generation of hydrogen gas through cotton stalk hydrolysate fermentation by Klebsiella sp. WL1316. Genome annotation indicated that the genome size was 5.2 Mb with GC content 57.6%. Xylose was metabolized in the pentose phosphate pathway via the conversion of xylose to xylulose in Klebsiella sp. WL1316. This strain contained diverse formate-hydrogen lyases and hydrogenases with gene numbers higher than closely related species. A metabolic network involving glucose, xylose utilisation, and fermentative hydrogen production was reconstructed. Metabolic analysis of key node metabolites showed that glucose and xylose metabolism influenced biomass synthesis and biohydrogen production. Formic acid accumulated during fermentation at 24–48 h but decreased sharply after 48 h, illustrating the splitting of formic acid to hydrogen gas during early-to-mid fermentation. The Kreb’s cycle was the main competitive metabolic branch of biohydrogen synthesis at 24 h of fermentation. Lactic and acetic acid fermentation and late ethanol accumulation competed the carbon skeleton of biohydrogen synthesis after 72 h of fermentation, indicating that these competitive pathways are regulated in middle-to-late fermentation (48–96 h). This study is the first to elucidate the metabolic mechanisms of mixed sugar utilisation and biohydrogen synthesis based on genomic information.(AU)

Indole-Acetic Acid Promotes Ammonia Removal Through Heterotrophic Nitrification, Aerobic Denitrification With Mixed Enterobacter sp. Z1 and Klebsiella sp. Z2.

Mixed Enterobacter sp. Z1 and Klebsiella sp. Z2 displayed an outstanding ammonia removal capacity than using a single strain. Metabolomics, proteomics, and RNA interference analysis demonstrated that the HNAD process was closely related to indole-acetic acid (IAA). Under the cocultured conditions, the excess IAA produced by Z2 could be absorbed by Z1 to compensate for the deficiency of IAA in the cells. IAA directly induced the expression of denitrifying enzymes and further activated the IAA metabolism level, thus greatly improving the nitrogen removal ability of Z1. In turn, nitrate and nitrite induced the expression of key enzymes in the IAA pathways. Moreover, Z1 and Z2 enhanced two IAA metabolic pathways in the process of mixed removal process. The activated hydrolysis-redox pathway in Z1 reduced the oxidative stress level, and the activated decarboxylation pathway in Z2 promoted intracellular energy metabolism, which indirectly promoted the process of HNAD in the system.

Co-metabolic biodegradation of structurally discrepant dyestuffs by Klebsiella sp. KL-1: A molecular mechanism with regards to the differential responsiveness.

In this study, an attempt was made to decipher the underlying differential response mechanism of Klebsiella sp. KL-1 induced by exposure to disparate categories of dyestuffs in xylose (Xyl) co-metabolic system. Here, representative reactive black 5 (RB5), remazol brilliant blue R (RBBR) and malachite green (MG) belonging to the azo, anthraquinone and triphenylmethane categories were employed as three model dyestuffs. Klebsiella sp. KL-1 enabled nearly 98%, 80% or 97% removal of contaminants in assays Xyl + RB5, Xyl + RBBR or Xyl + MG after 48 h, which was respectively 16%, 11% or 22% higher than those in the assays devoid of xylose. LC-QTOF-MS revealed an increased formation of smaller molecular weight intermediates in assay Xyl + RB5, whereas more metabolic pathways were deduced in assay Xyl + RBBR. Metaproteomics analysis displayed remarkable proteome alteration with regards to the structural difference effect of dyestuffs by Klebsiella sp. KL-1. Significant (p-value<0.05) activation of pivotal candidate NADH-quinone oxidoreductase occurred after 48 h of disparate dyestuff exposure but with varying abundance. Dominant FMN-dependent NADH-azoreductase, Cytochrome d terminal oxidase or Thiol peroxidase were likewise deemed to be responsible for the catalytic cleavage of RB5, RBBR or MG, respectively. Further, the differential response mechanism towards the structurally discrepant dyestuffs was put forward. Elevated reducing force associated with the corresponding functional proteins/enzymes was transferred to the exterior of the cell to differentially decompose the target contaminants. Overall, this study was dedicated to provide in-depth insights into the molecular response mechanism of co-metabolic degradation of refractory and structurally discrepant dyestuffs by an indigenous isolated Klebsiella strain.

Comprehensive Transcriptomic Analysis of Heterotrophic Nitrifying Bacterium Klebsiella sp. TN-10 in Response to Nitrogen Stress.

Klebsiella sp. TN-10, a heterotrophic nitrifying bacterium, showed excellent nitrification ability under nitrogen stress. The strain was cultured under different nitrogen stress levels, including ammonium sulfate 0.5, 2.5, and 5 g/L, and samples were titled group-L, group-M, and group-H, respectively. In these three groups, the removed total nitrogen was 70.28, 118.33, and 157.18 mg/L after 12 h of cultivation, respectively. An RNA-Seq transcriptome analysis was used to describe key regulatory networks in response to nitrogen stress. The GO functional enrichment and KEGG enrichment analyses showed that differentially expressed genes (DEGs) participated in more pathways under higher nitrogen stress (group-H). Carbohydrate metabolism and amino acid metabolism were the most abundant subcategories, which meant these pathways were significantly influenced by nitrogen stress and could be related to nitrogen removal. In the nitrogen cycle, up-regulated gene2311 (narK, encodes major facilitator superfamily transporter) may accelerate the entry of nitrogen into the cells and subsequently contribute to the nitrogen utilization. In addition, the up-regulation of gene2312 (narG), gene2313 (narH), and gene2315 (narH) may accelerate denitrification pathways and facilitate nitrogen removal. The results presented in this study may play a pivotal role in understanding the regulation networks of the nitrifying bacterium TN-10 under nitrogen stress.

Genome mining discovery of hydrogen production pathway of Klebsiella sp. WL1316 fermenting cotton stalk hydrolysate.

Genome sequencing was used to identify key genes for the generation of hydrogen gas through cotton stalk hydrolysate fermentation by Klebsiella sp. WL1316. Genome annotation indicated that the genome size was 5.2 Mb with GC content 57.6%. Xylose was metabolized in the pentose phosphate pathway via the conversion of xylose to xylulose in Klebsiella sp. WL1316. This strain contained diverse formate-hydrogen lyases and hydrogenases with gene numbers higher than closely related species. A metabolic network involving glucose, xylose utilisation, and fermentative hydrogen production was reconstructed. Metabolic analysis of key node metabolites showed that glucose and xylose metabolism influenced biomass synthesis and biohydrogen production. Formic acid accumulated during fermentation at 24-48 h but decreased sharply after 48 h, illustrating the splitting of formic acid to hydrogen gas during early-to-mid fermentation. The Kreb's cycle was the main competitive metabolic branch of biohydrogen synthesis at 24 h of fermentation. Lactic and acetic acid fermentation and late ethanol accumulation competed the carbon skeleton of biohydrogen synthesis after 72 h of fermentation, indicating that these competitive pathways are regulated in middle-to-late fermentation (48-96 h). This study is the first to elucidate the metabolic mechanisms of mixed sugar utilisation and biohydrogen synthesis based on genomic information.

Identification of functional genes associated with the biotransformation of limonene to trans-dihydrocarvone in Klebsiella sp. O852.

BACKGROUND: Natural dihydrocarvone has been widely used in the food, cosmetics, agrochemicals and pharmaceuticals industries because of its sensory properties and physiological effects. In our previous study, Klebsiella sp. O852 was shown to be capable of converting limonene to trans-dihydrocarvone with high catalytic efficiency. Thus, it was essential to identify and characterize the functional genes involved in limonene biotransformation using genome sequencing and heterologous expression. RESULTS: The 5.49-Mb draft genome sequence of Klebsiella sp. O852 contained 5218 protein-encoding genes. Seven candidate genes participating in the biotransformation of limonene to trans-dihydrocarvone were identified by genome analysis. Heterologous expression of these genes in Escherichia coli BL21(DE3) indicated that 0852_GM005124 and 0852_GM003417 could hydroxylate limonene in the six position to yield carveol, carvone and trans-dihydrocarvone. 0852_GM002332 and 0852_GM001602 could catalyze the oxidation of carveol to carvone and trans-dihydrocarvone. 0852_GM000709, 0852_GM001600 and 0852_GM000954 had high carvone reductase activity toward the hydrogenation of carvone to trans-dihydrocarvone. CONCLUSION: The results obtained in the present study suggest that the seven genes described above were responsible for converting limonene to trans-dihydrocarvone. The present study contributes to providing a foundation for the industrial production of trans-dihydrocarvone in microbial chassis cells using synthetic biology strategies. © 2021 Society of Chemical Industry.

Metabolic regulation and optimization of oxygen supply enhance the 2,3-butanediol yield of the novel Klebsiella sp. isolate FSoil 024.

BACKGROUND: Biogenic 2,3-butanediol (2,3-BDO) is a high-value-added compound that can be used as a liquid fuel and a platform chemical. Bioproduction of 2,3-BDO is an environmentally friendly choice. METHOD AND RESULTS: Three recombinant derivatives of the novel Klebsiella sp. isolate FSoil 024 (WT) were constructed via different strategies including deletion of lactate dehydrogenase by λ-Red homologous recombination technology, overexpression of the small-noncoding RNA RyhB and a combination of both. The 2,3-BDO productivity of the mutants increased by 61.3%-79%, and WT-Δldh/ryhB displayed the highest 2,3-BDO yield of 42.36 mM after 24 h of shake-flask fermentation. Glucose was shown as the best carbon source for 2,3-BDO production by WT-Δldh/ryhB. In addition, higher oxygenation was favorable for ideal product synthesis. The maximal 2,3-BDO yield of WT and WT-Δldh/ryhB were increased by 23.3% and 52.5% respectively compared to the control group in the presence of 70% oxygen (V:V' = O2 :(O2 + N2 )). CONCLUSION AND IMPLICATIONS: According to the present study, deletion of lactate dehydrogenase, RyhB overexpression, and manipulation of oxygen supply showed great impacts on cell growth, 2,3-BDO productivity and cellular metabolism of the novel isolated strain Klebsiella sp. FSoil 024. This work would also provide insights for promoting 2,3-BDO biosynthesis for industrial applications.

Klebsiella sp.-related infectious spondylitis in a bearded dragon (Pogona vitticeps).

BACKGROUND: Spondylitis is an inflammation of the vertebrae that leads to a destructive process with exuberant new bone formation. Osteomyelitis can produce a distortion of the bone architecture, degenerative joint changes and ankyloses of adjacent vertebrae. In reptiles, intervertebral discs are absent, so the term discospondylitis is not used. In lizards, vertebral lesions have not been well studied. The present paper describes the first case of Klebsiella sp.-related spondylitis in a pet lizard (Pogona vitticeps). CASE PRESENTATION: A 2-year-old, female bearded dragon (Pogona vitticeps) was presented for clinical examination due to a decreased activity level, decreased appetite and constipation. Blood tests showed no remarkable alterations. The haemogram showed normal parameters with relative lymphocytosis, although the absolute number of lymphocytes did not differ from the reference values. A computed tomography scan revealed a mixed osteolytic-proliferative bone lesion diffusing to the first and last tracts of the pre-sacral vertebrae together. A small amount of material obtained from the spinal swelling was sampled with an aseptic technique for bacterial culture, which was positive for Klebsiella sp. The antibiogram revealed sensitivity to enrofloxacin, marbofloxacin, and chloramphenicol and intermediate sensitivity to gentamicin. Complete return to spontaneous feeding was achieved 15 days after the beginning of antibiotic and anti-inflammatory therapy. CONCLUSIONS: In veterinary medicine, spondylitis represents a well-known disease in small companion animals. In mammals, the most common aetiologic agents are fungi and bacteria. Antibiotic therapy was set based on the antibiogram, and marbofloxacin was chosen at a dosage of 10 mg/kg subcutaneously (SC) once per day (SID). After only 7 days of antibiotic therapy, the clinical condition improved significantly; the patient started feeding and drinking spontaneously and gained weight. This case should remind clinicians of the importance of always performing antibiograms before choosing any antibiotic therapy. Considering reptiles, there have been few papers about spinal diseases, mostly regarding snakes and a few about Iguana iguana. Relative to other species of saurians, the literature remains lacking.

Transcriptome Analysis Reveals Cr(VI) Adaptation Mechanisms in Klebsiella sp. Strain AqSCr.

Klebsiella sp. strain AqSCr, isolated from Cr(VI)-polluted groundwater, reduces Cr(VI) both aerobically and anaerobically and resists up 34 mM Cr(VI); this resistance is independent of the ChrA efflux transporter. In this study, we report the whole genome sequence and the transcriptional profile by RNA-Seq of strain AqSCr under Cr(VI)-adapted conditions and found 255 upregulated and 240 downregulated genes compared to controls without Cr(VI) supplementation. Genes differentially transcribed were mostly associated with oxidative stress response, DNA repair and replication, sulfur starvation response, envelope-osmotic stress response, fatty acid (FA) metabolism, ribosomal subunits, and energy metabolism. Among them, genes not previously associated with chromium resistance, for example, cybB, encoding a putative superoxide oxidase (SOO), gltA2, encoding an alternative citrate synthase, and des, encoding a FA desaturase, were upregulated. The sodA gene encoding a manganese superoxide dismutase was upregulated in the presence of Cr(VI), whereas sodB encoding an iron superoxide dismutase was downregulated. Cr(VI) resistance mechanisms in strain AqSCr seem to be orchestrated by the alternative sigma factors fecl, rpoE, and rpoS (all of them upregulated). Membrane lipid analysis of the Cr(IV)-adapted strain showed a lower proportion of unsaturated lipids with respect to the control, which we hypothesized could result from unsaturated lipid peroxidation followed by degradation, together with de novo synthesis mediated by the upregulated FA desaturase-encoding gene, des. This report helps to elucidate both Cr(VI) toxicity targets and global bacterial response to Cr(VI).

Isolation and identification of naphthalene degrading bacteria and their degradation characteristics under rainwater environment in heavily polluted areas.

This study is screened for naphthalene degrading strains from a heavily polluted area with high naphthalene concentration in the rainwater for the effective removal of naphthalene from rainwater. Recently, naphthalene biodegradation has been achieved in water. However, the influences of organics and inorganics in the rainwater on the biodegradation of naphthalene remains unclear. The naphthalene degrading strain Klebsiella sp. (WJ-1) was identified from sewage sludge. The effects of temperature, pH, inoculum size, and rotation speed on the degradation ability of WJ-1 were studied. The results showed that the naphthalene degradation rates of WJ-1 in rainwater were higher than those in aqueous solution at different experimental conditions. The optimal conditions were 30 °C, 10% inoculum size, pH 7.0, and a rotation speed of 150 rpm. The substances in rainwater might be important co-metabolites of naphthalene degradation. Based on intermediate metabolites detected by gas chromatography-mass spectrometer (GC-MS), the naphthalene biodegradation pathway was identified, as being similar to the phthalic acid pathway. These results suggest WJ-1 as a good candidate for the efficient bioremediation of naphthalene from rainwater in heavily polluted areas.

Screening a Strain of Klebsiella sp. O852 and the Optimization of Fermentation Conditions for Trans-Dihydrocarvone Production.

Flavors and fragrances have high commercial value in the food, cosmetic, chemical and pharmaceutical industries. It is interesting to investigate the isolation and characterization of new microorganisms with the ability to produce flavor compounds. In this study, a new strain of Klebsiella sp. O852 (accession number CCTCC M2020509) was isolated from decayed navel orange (Citrus sinensis (L.) Osbeck), which was proved to be capable of converting limonene to trans-dihydrocarvone. Besides, the optimization of various reaction parameters to enhance the trans-dihydrocarvone production in shake flask was performed for Klebsiella sp. O852. The results showed that the yield of trans-dihydrocarvone reached up to 1 058 mg/L when Klebsiella sp. O852 was incubated using LB-M medium for 4 h at 36 °C and 150 rpm, and the biotransformation process was monitored for 36 h after adding 1680 mg/L limonene/ethanol (final ethanol concentration of 0.8% (v/v)). The content of trans-dihydrocarvone increased 16 times after optimization. This study provided a basis and reference for producing trans-dihydrocarvone by biotransformation.

Production, functional stability, and effect of rhamnolipid biosurfactant from Klebsiella sp. on phenanthrene degradation in various medium systems.

The present study investigated the stability and efficacy of a biosurfactant produced by Klebsiella sp. KOD36 under extreme conditions and its potential for enhancing the solubilization and degradation of phenanthrene in various environmental matrices. Klebsiella sp. KOD36 produced a mono-rhamnolipids biosurfactant with a low critical micelle concentration (CMC) value. The biosurfactant was stable under extreme conditions (60 °C, pH 10 and 10% salinity) and could lower surface tension by 30% and maintained an emulsification index of > 40%. The emulsion index was also higher (17-43%) in the presence of petroleum hydrocarbons compared to synthetic surfactant Triton X-100. Investigation on phenanthrene degradation in three different environmental matrices (aqueous, soil-slurry and soil) confirmed that the biosurfactant enhanced the solubilization and biodegradation of phenanthrene in all matrices. The high functional stability and performance of the biosurfactant under extreme conditions on phenanthrene degradation show the great potential of the biosurfactant for remediation applications under harsh environmental conditions.

Egg-Surface Bacteria Are Indirectly Associated with Oviposition Aversion in Bactrocera dorsalis.

Finding a suitable oviposition site is a challenging task for a gravid female fly, because the hatched maggots have limited mobility, making it difficult to find an alternative host. The oriental fruit fly, Bactrocera dorsalis, oviposits on many types of fruits. Maggots hatching in a fruit that is already occupied by conspecific worms will face food competition. Here, we showed that maggot-occupied fruits deter B. dorsalis oviposition and that this deterrence is based on the increased ß-caryophyllene concentration in fruits. Using a combination of bacterial identification, volatile content quantification, and behavioral analyses, we demonstrated that the egg-surface bacteria of B. dorsalis, including Providencia sp. and Klebsiella sp., are responsible for this increase in the ß-caryophyllene contents of host fruits. Our research shows a type of tritrophic interaction between micro-organisms, insects, and insect hosts, which will provide considerable insight into the evolution of insect behavioral responses to volatile compounds.

Bacterial cellulase from the intestinal tract of the sugarcane borer.

Cellulolytic enzymes have wide use in several industrial segments (e.g. biofuels, pulp and paper, food, and cosmetics). However, one of the challenges is their large-scale production with high specific activity to eliminate the dependence of the purchase of enzymatic cocktails produced by commercial parties. The aims of this study were (1) isolation, selection, and partial characterization of bacterial cellulases present in the intestinal tract of the sugarcane borer and (2) to identify cellulase-producing bacteria by analyzing the 16S rDNA gene. Cellulase production and purification assays resulted in similar electrophoretic profiles between four bacterial strains. These strains were identified as Klebsiella pneumoniae, Klebsiella sp., and Bacillus sp. K. pneumoniae was the main cellulase-producing microorganism. Our results show the possibility of finding cellulolytic microorganisms that inhabit the gut of herbivorous animals, especially those that are predators of important crops of economic value. Furthermore, K. pneumoniae cellulase is of medical importance. In hospitals, health professionals, hospital technicians, patients and visitors wear clothes containing cellulose. Thus, K. pneumoniae within hospitals can contaminate these clothes and be spread to the environment. In that case, it would be important for the hospital's chemical sterilization products to have at least one cellulase inhibitor.

Prevalence of Multi-Antibiotic Resistant Escherichia coli and Klebsiella species obtained from a Tertiary Medical Institution in Oyo State, Nigeria.

Background: The development of multi-antibiotic resistant bacteria, especially Gram-negative bacteria which are the major cause of hospital-acquired infections worldwide, had been increasing. Escherichia coli and Klebsiella sp. had become more resistant to different classes of antibiotics, and the treatment of infections caused by these bacteria had developed into a challenge in both developed and developing countries. This study had determined the multi-antibiotic resistance (MAR) patterns of Escherichia coli and Klebsiella sp. isolated from clinical inpatient and outpatient samples. Method: The present study had used 50 E. coli and 48 Klebsiella sp. isolates. Antibiotic susceptibility test had been carried out by using disk diffusion method, and the interpretation of results of the zones of inhibition had accorded with Clinical Laboratory Standards Institute (CLSI). The antibiotics used had included the following: streptomycin, ciprofloxacin, erythromycin, nitrofurantoin, amikacin, gentamicin, ofloxacin, cefepime, oxacillin, colistin sulfate, cefotaxime, ceftazidime, pefloxacine, and cloxacillin. Results: E. coli and K. pneumoniae had shown high-resistance patterns. E. coli had exhibited high resistance against cloxacillin (96%), oxacillin (96%), erythromycin (88%), and most especially streptomycin (98%). Similarly, K. pneumoniae had presented a high resistance to streptomycin (88%), cloxacillin (92%), oxacillin (92%), and colistin (92%). E. coli had presented the highest multidrug resistance with a MAR index of 1.00. A total of 17 E. coli isolates had shown resistance to the 14 antibiotics tested. Conclusion: E. coli and Klebsiella sp. in clinical isolates in outpatients and inpatients in Ibadan, Western Nigeria had demonstrated high antimicrobial resistance. Thus, such condition should be considered a major public health concern, and measures must be taken to establish the sources and drivers of this problem.