Shorter Lag Phase Research Articles

Characteristics of head and neck squamous cell carcinoma cell Lines reflect human tumor biology independent of primary etiologies and HPV status

Explanations for the differences in clinical outcomes in head and neck squamous cell carcinomas (HNSCCs) when compared by similar tumor location, stage, nodal status, human papillomavirus (HPV) status, and patient history remain elusive. Cell lines are an excellent tool of study for understanding the in vitro properties of cancers. However, HNSCC cell lines from progression-free and/or HPV-positive tumors are very rare. Here we studied HPV-positive and HPV-negative University of Michigan squamous cell carcinoma cell lines (2 HPV−, 2 HPV16+, 1 HPV18+) coming from donors with nonoropharyngeal sites and variant clinical outcomes. Cell morphology and proliferation were assessed, and immunofluorescence and Western blotting evaluated tumor biomarkers (TP53, RB1, p16, HPV E6 and E7, EGFR, Cyclin D1, Ki-67, and beta-catenin). Slow in vitro proliferation, long lag phase before exponential proliferation, lower maximal cell density, and higher wild-type TP53 expression were common to cell lines from patients who experienced long-term disease-free survival. In contrast, shorter lag phases, rapid proliferation, and high maximal cell density were observed in cell lines from patients who experienced aggressive tumor progression leading to death. Membrane-bound beta-catenin was present in all cell lines, but nuclear beta-catenin was associated with the more lethal cancers. In summary, the HNSCC cell lines present key characteristics, independent of primary etiologies and HPV infection, that mirror the behavior of the tumors from which they were derived.

Powdered activated carbon facilitates methane productivity of anaerobic co-digestion via acidification alleviating: Microbial and metabolic insights

Low methanogenic efficiency caused by excess acidification is a challenge during anaerobic digestion. This study indicated that both granular activated carbon (GAC) and powdered activated carbon (PAC) promoted the start-up of methanogenesis and methane output in anaerobic co-digestion of food waste and fruit-vegetable waste. Moreover, PAC performed better than GAC. Specifically, the highest cumulative methane yield and shortest lag phase were observed in 5 g/L PAC and 10 g/L PAC group, 22.0% higher and 62.5% shorter than that without activated carbon supplementation, respectively. PAC facilitated the methane productivity by effectively accelerating volatile fatty acids (VFAs) consumption and thereby alleviating acidification. Syntrophic VFAs oxidizing bacteria (Gelria and Syntrophomonas) and direct interspecies electron transfer related microorganisms (Geobacter and Methanosarcina) were remarkably enriched by PAC. Furthermore, metagenomic analysis showed that both PAC and GAC might facilitate the electron transfer between microbes by acting as the electrical bridge and enhance both hydrogenotrophic and aceticlastic pathways.

Enhanced biohydrogen production from cotton stalk hydrolysate of Enterobacter cloacae WL1318 by overexpression of the formate hydrogen lyase activator gene

BackgroundBiohydrogen production from lignocellulose has become an important hydrogen production method due to its diversity, renewability, and cheapness. Overexpression of the formate hydrogen lyase activator (fhlA) gene is a promising tactic for enhancement of hydrogen production in facultative anaerobic Enterobacter. As a species of Enterobacter, Enterobacter cloacae was reported as a highly efficient hydrogen-producing bacterium. However, little work has been reported in terms of cloning and expressing the fhlA gene in E. cloacae for lignocellulose-based hydrogen production.ResultsIn this study, the formate hydrogen lyase activator (fhlA) gene was cloned and overexpressed in Enterobacter cloacae WL1318. We found that the recombinant strain significantly enhanced cumulative hydrogen production by 188% following fermentation of cotton stalk hydrolysate for 24 h, and maintained improved production above 30% throughout the fermentation process compared to the wild strain. Accordingly, overexpression of the fhlA gene resulted in an enhanced hydrogen production potential (P) and maximum hydrogen production rate (Rm), as well as a shortened lag phase time (λ) for the recombinant strain. Additionally, the recombinant strain also displayed improved glucose (12%) and xylose (3.4%) consumption and hydrogen yield Y(H2/S) (37.0%) compared to the wild strain. Moreover, the metabolites and specific enzyme profiles demonstrated that reduced flux in the competitive branch, including succinic, acetic, and lactic acids, and ethanol generation, coupled with increased flux in the pyruvate node and formate splitting branch, benefited hydrogen synthesis.ConclusionsThe results conclusively prove that overexpression of fhlA gene in E. cloacae WL1318 can effectively enhance the hydrogen production from cotton stalk hydrolysate, and reduce the metabolic flux in the competitive branch. It is the first attempt to engineer the fhlA gene in the hydrogen-producing bacterium E. cloacae. This work provides a highly efficient engineered bacterium for biohydrogen production from fermentation of lignocellulosic hydrolysate in the future.

Strain Variability of Listeria monocytogenes under NaCl Stress Elucidated by a High-Throughput Microbial Growth Data Assembly and Analysis Protocol.

Listeria monocytogenes causes the severe foodborne illness listeriosis and survives in food-associated environments due to its high stress tolerance. A data assembly and analysis protocol for microbial growth experiments was compiled to elucidate the strain variability of L. monocytogenes stress tolerance. The protocol includes measurement of growth ability under stress (step 1), selection of a suitable method for growth parameter calculation (step 2), comparison of growth patterns between strains (step 3), and biological interpretation of the discovered differences (step 4). In step 1, L. monocytogenes strains (n = 388) of various serovars and origins grown on media with 9.0% NaCl were measured using a Bioscreen C microbiology reader. Technical variability of the growth measurements was assessed and eliminated. In step 2, the growth parameters determined by Gompertz, modified-Gompertz, logistic, and Richards models and model-free splines were compared, illustrating differences in the suitability of these methods to describe the experimental data. In step 3, hierarchical clustering was used to describe the NaCl tolerance of L. monocytogenes measured by strain-specific variation in growth ability; tolerant strains had higher growth rates and maximum optical densities and shorter lag phases than susceptible strains. The spline parameter area under the curve best classified "poor," "average," and "good" growers. In step 4, the tested L. monocytogenes lineage I strains (serovars 4b and 1/2b) proved to be significantly more tolerant toward 9.0% NaCl than lineage II strains (serovars 1/2a, 1/2c, and 3a). Our protocol provides systematic tools to gain comparable data for investigating strain-specific variation of bacterial growth under stress.IMPORTANCE The pathogen Listeria monocytogenes causes the foodborne disease listeriosis, which can be fatal in immunocompromised individuals. L. monocytogenes tolerates several environmental stressors and can persist in food-processing environments and grow in foodstuffs despite traditional control measures such as high salt content. Nonetheless, L. monocytogenes strains differ in their ability to withstand stressors. Elucidating the intraspecies strain variability of L. monocytogenes stress tolerance is crucial for the identification of particularly tolerant strains. To enhance reliable identification of variability in bacterial stress tolerance phenotypes, we compiled a large-scale protocol for the entire data assembly and analysis of microbial growth experiments, providing a systematic approach and checklist for experiments on strain-specific growth ability. Our study illustrated the diversity and strain-specific variation of L. monocytogenes stress tolerance with an unprecedented scope and discovered biologically relevant serovar- and lineage-dependent phenotypes of NaCl tolerance.

Anaerobic bioconversion of petrochemical wastewater to biomethane in a semi-continuous bioreactor: Biodegradability, mineralization behaviors and methane productivity

Petrochemical wastewaters treatment represents a serious challenge due to the high toxicity and complex chemical components. In this study, the biodegradability, mineralization behaviors and methane productivity of eight different types of petrochemical wastewaters were evaluated in series of semi-continuous bioreactors. Methane production strongly depended on the characteristics of wastewaters and chemical constituents. The highest methane yield of 305.9 ± 2.7 mL/g-COD was achieved by purified terephthalic acid wastewater, followed by ethylene glycol, polyester, etc. Comparatively, one-step-SCN− wastewater produced the lowest methane yield (4.7 ± 0.7 mL/g-COD) owing to high toxicity and low biodegradability. Modified Gompertz model confirmed that purified terephthalic acid, ethylene glycol and polyester wastewaters had a short lag-phase of 1.2, 1.7 and 0.2 days, respectively. Nonetheless, the formation of by-products such as proteins, polysaccharides and ammonia nitrogen throughout anaerobic digestion reflected the high activity of anaerobic microorganisms, confirming the technical feasibility of anaerobic biotechnology in treating petrochemical wastewaters.

Leachate recirculation effects on solid‐state anaerobic digestion of Pennisetum hybrid and microbial community analysis

AbstractBACKGROUNDA leach‐bed reactor (LBR) with leachate recirculation is a suitable technology for lignocellulosic biomass anaerobic digestion. In this study, the effect of percolate reflux strategies (continuous recirculation and intermittent recirculation) on methane production from Pennisetum hybrid, a type of energy crop, was investigated using a two‐layered LBR.RESULTSCompared to a solid‐state anaerobic digestion batch test, LBRs with percolate recirculation provide a stable process with a short lag phase by avoiding inhibition of volatile fatty acid accumulation and inoculation effect. The results also indicated that continuous reflux led to a lower accumulative methane yield (56.20 L kg−1 VS) compared to intermittent reflux (78.50 L kg−1 VS), resulting from washing effect and poorer distribution on the lower layer. According to microbial analysis, Bacteroidetes, Firmicutes, Proteobacteria and Synergistetes were the most predominant bacterial phyla in each LBR test sample and aceticlastic methanogen (at least >55%) plays a predominant role for methane production in all samples.CONCLUSIONSThe results indicate that leachate recirculation could provide stable conditions for methane yield; however, two‐layer reactor designs which cannot guarantee the desired distribution in the lower layer result in a low methane yield. Suitable design of LBRs to maintain a well‐distributed reflux leachate should be further investigated. © 2019 Society of Chemical Industry

Impacts of antibiotic contaminants on Microcystis aeruginosa during potassium permanganate treatment

Application of KMnO4 for preventing the formation of cyanobacterial bloom at early growth stage has not been reported. Antibiotics generate hormesis effects in cyanobacteria at currently reported concentrations, which may negatively affect the control of cyanobacterial bloom. This study assessed the treatment performance of KMnO4 in Microcystis aeruginosa with and without the existence of the antibiotic mixture composed of four simultaneously detected antibiotics in aquatic environments (sulfamethoxazole, ciprofloxacin, amoxicillin and tetracycline). KMnO4 downregulated two chlorophyll a synthetases (chlG and chlM), 14 photosynthesis-related proteins and two microcystin synthetases (mcyB and mcyD) in M. aeruginosa, and reduced chlorophyll a content, photosynthetic activity and microcystin concentration in a dose-dependent manner. Inhibition of photosynthesis and biosynthesis resulted in extended lag phase and decreased growth rate in KMnO4-treated Microcystis aeruginosa. In contrast, mixed antibiotics upregulated 6 oxidation-reduction proteins, a cell division regulatory protein (MAE_37210), 14 photosynthesis-related proteins, 14 biosynthesis-related proteins (including microcystin synthetases mcyA and mcyB) and a microcystin transport protein (mcyH), which consequently reduced oxidative stress, shortened lag phase as well as significantly stimulated (p < 0.05) cyanobacterial growth, photosynthetic activity, microcystin synthesis and microcystin release in KMnO4-treated M. aeruginosa. An optimal dose of 3 mg L−1 was suggested for KMnO4 treatment. Mixed antibiotics should be controlled below a no-impact threshold of 20 ng L−1 (5 ng L-1 for each antibiotic) for eliminating their adverse effects during KMnO4 treatment of cyanobacteria in antibiotics polluted environments.

The Ethanol Production Activity of Indigenous Thermotolerant Yeast Pichia kudriavzevii 1P4

Pichia kudriavzevii 1P4 is a thermotolerant-ethanologenic yeast potential for application in ethanol industry. In this study we evaluated the stress tolerance phenotype of P. kudriavzevii 1P4 in dealing with fermentation related-stresses, including high temperature stress, high sugar content, ethanol content and the fermentation capacity of the particular isolate. Based on spot assay, 1P4 showed stress tolerance phenotype against high sugar concentration for up to 30% sugar content and 10% ethanol stress. In addition, 1P4 was capable to show temperature-stress tolerance phenotype for up to 42oC, suggesting that 1P4 belong to thermotolerant yeast isolate. Fermentative activity was measured by using glucose consumption and ethanol production assay. We evaluated the fermentative and growth rate of 1P4 at various temperature condition which were 27oC, 37oC and 42oC using YPD media (at initial glucose of 2%, 10% and 20%). Interestingly, 1P4 consumed the highest glucose in 20% of concentration at 37oC (15.29%), simultaneously with the highest concentration of ethanol (32.05 g/L ethanol and 0.67 g/L/h ethanol productivity). Cell growth analysis showed that growth of 1P4 isolate increased with higher initial glucose condition yet decreased as temperature during fermentation was raised. The growth rate of 1P4 was found high in 20% initial glucose at 37oC than 2% and 10% at same temperature. In addition, 1P4 exhibited short lag phase at high-temperature fermentation. Our data indicate that 1P4 can potentially be applied as fermentation agent especially in high-temperature ethanol fermentation. Key words: bioethanol production, fermentation related-stress, thermotolerant yeast

Plasma Fibrin Clot Properties Are Unfavorably Altered in Women following Venous Thromboembolism Associated with Combined Hormonal Contraception.

The use of hormonal contraception is associated with an increased risk of venous thromboembolism (VTE). Unfavorably altered fibrin clot phenotype has been reported in patients following unprovoked VTE who are at risk of recurrences. It remains unknown whether fibrin clot characteristics in women with contraception-related VTE differ from those in unprovoked VTE. We studied three age-matched groups of women: (1) after contraception-related VTE, (n = 48) (2) after unprovoked VTE (n = 48), and (3) controls (n = 48). Plasma fibrin clot permeability (Ks), turbidity of clot formation, efficiency of fibrinolysis using clot lysis time (CLT), and rate of increase in D-dimer during lytic clot degradation (D-Drate), along with thrombin generation and fibrinolysis proteins were determined. Compared with the controls, patients following contraception-related and unprovoked VTE formed faster (lag phase, -8.8% and -20.4%, respectively) fibrin clots of increased density (Ks, -8.6% and -13.4%, respectively) displaying impaired fibrinolysis as evidenced by prolonged CLT (+11.5% and +14.5%, respectively) and lower D-Drate (-7.1% and -5.6%, respectively), accompanied with higher plasminogen activator inhibitor-1 (PAI-1, +14.9% and +17.8%, respectively) and elevated peak thrombin generation (+63.8% and +36.7%, respectively). The only differences between women with unprovoked and contraception-related VTE were lower fibrin mass in plasma clots (D-Dmax, -8.6%), along with higher peak thrombin generation (+19.8%) and shorter lag phase (-6.8%) in the latter group. This study suggests that women after contraception-related VTE, similar to those following unprovoked VTE, have denser fibrin clot formation and impaired clot lysis. These findings might imply higher risk of VTE recurrence in women with the prothrombotic clot phenotype.

Sex-specific alteration to α2-antiplasmin incorporation in patients with type 2 diabetes

BackgroundType 2 diabetes mellitus (T2DM) is associated with hypofibrinolysis and increased factor XIII-mediated α2-antiplasmin incorporation into the fibrin clot. It is unclear whether there are sex-related differences in α2-antiplasmin incorporation in relation to impaired clot lysis in T2DM. AimWe investigated α2-antiplasmin incorporation into fibrin clots as a determinant of clot lysability in patients of both sexes with T2DM. MethodsIn a group of 113 T2DM patients, 54 (47.8%) of which were women, we investigated α2-antiplasmin incorporation using an in-house sandwich enzyme-linked immunoassay and plasma clot lysis by turbidimetry, along with fibrinogen and thrombin generation using calibrated automated thrombogram and factor XIII activity. ResultsFemale patients had 15.2% greater α2-antiplasmin incorporation into the fibrin clot (p = 0.008) and slightly higher plasma α2-antiplasmin concentration (p = 0.005) along with 8.4% longer time to 50% lysis (Lys50MA, p = 0.012) compared with men. Female patients had enhanced thrombin generation represented by shorter lag phase (p = 0.042), shorter time to peak (p = 0.033), and higher endogenous thrombin potential (p = 0.003) compared with men, while factor XIII activity was comparable between sexes (p = 0.085). On multivariate regression, patient sex and glycated hemoglobin (HbA1c) level were the predictors of α2-antiplasmin incorporation in the entire patient group, while α2-antiplasmin incorporation was associated with Lys50MA, as were fibrinogen, male sex and body-mass index. ConclusionsThis study suggests that a more compromised fibrinolysis in diabetic women when compared with men could be in part mediated by increased α2-antiplasmin incorporation into the fibrin.

Influence of pH controlling on fermentation performance in kitchen waste and cow manure

ABSTRACT In order to make the process more sustainability and more efficient in co-digestion of kitchen waste (KW) and cow manure (CM), the effect of pH controlling at initial fermentation time (I), first gas stagnation time (A), and combination of both times (C) were investigated. Five pH values (6.5, 7.0, 7.5, 8.0 and 8.5) were set in each case to find out the optimal way of pH regulation with the consideration of changes in biogas and methane production, volatile solid (VS) reduction, and lag-phase time. The results show that adjusting pH of the co-digestion system could significantly improve biogas production except when pH was set to 6.5 in groups I and A. Adjusting pH twice (group C) could increase the system stability. When pH value was set to 7.5 twice, highest methane production (16501.10 mL), the highest methane yield of 287.64 mL/g VSadded, and a relatively short lag-phase time (27.3d) were obtained by C7.5.

Screening a genomic library for genes involved in propionate tolerance in Yarrowia lipolytica.

Microbial oils are regarded as promising alternatives to fossil fuels. For bio-oil production to be sustainable over the long term, utilizing low-cost substrates like volatile fatty acids (VFAs) is crucial. Increasing attention is being paid to one of the most common VFAs: propionate, a substrate that could be used to produce the odd-chain FAs of industrial interest. However, little is known about microbial responses to propionate-induced stress and the genes involved. Using genomic library screening, we identified two genes involved in propionate tolerance in Yarrowia lipolytica-MFS1 and RTS1. Strains containing each of the genes displayed enhanced tolerance to propionate even when the genes were expressed in truncated form via a replicative plasmid. Compared with the control strain, the strain overexpressing MFS1 under a constitutive promoter displayed greater tolerance to propionate: It had a shorter lag phase and higher growth rate in propionate medium (0.047hr-1 versus 0.030hr-1 for the control in 40g/L propionate); it also accumulated more total lipids and more odd-chain lipids (10% and 3.3%, respectively) than the control. The strain overexpressing RTS1 showed less tolerance for propionate than the strains harboring the truncated form (0.057hr-1 versus 0.065hr-1 in 40g/L propionate medium) but still had higher tolerance than the control strain. Furthermore, the overexpression of RTS1 seemed to confer tolerance to other weak acids such as lactate, formic acid, malic acid, and succinic acid. This work provides a basis for better understanding the response to propionate-induced stress in Y.lipolytica.

Enzymatic and Hydrothermal Pretreatment of Newly Isolated Spirulina subsalsa BGLR6 Biomass for Enhanced Biogas Production

The complex structure and biochemical composition of the cell wall of microalgae impede their anaerobic digestion. To enhance the microalgae anaerobic biodegradability, various pretreatment approaches have been utilized. In this study, the enzyme and hydrothermal pretreatment methods were evaluated for microalgal biomass pretreatment and biogas yield. The optical and scanning electron microscopy along with Fourier transform infrared spectroscopy analysis confirmed the efficient action of both the pretreatment methods. The hydrothermal pretreatment resulted in more structural changes, though the increase in enzymatic concentration was also found to have a pronounced effect on both structural and chemical changes. The FTIR spectra determined that mostly the protein and carbohydrate structures of the microalgal cells were affected. Further upon quantitative analysis, it was observed that 10% dose (w/w) for 24 h of exposure time released significantly more soluble chemical oxygen demand compared to others. The multi-enzyme 10% dose for 24 h resulted in significantly higher biogas production potential (P) of 768.92 mL g−1 VS at a maximum biogas production rate (Rm) of 32.16 mL g−1 d−1 with a very short lag phase (λ) of 0.09 days at the end of 30 days, in comparison to untreated and other pretretment conditions in this study. Both the pretreatment approaches in the present study enhanced the microalgal biomass disintegration, digestibility and biogas production. However, more research is required to optimize the process parameters of these pretreatment approaches to make them more reasonable and applicable.

Efficient succinic acid production using a biochar-treated textile waste hydrolysate in an in situ fibrous bed bioreactor

Textile waste contains biodegradable fraction which can be used as an alternative feedstock for succinic acid production. The feasibility of bioconversion of biochar-treated textile waste hydrolysate into succinic acid was evaluated. A substrate loading of 9% was applied to hydrolyze mixed textile waste and the resultant glucose-rich hydrolysate with dyestuff was collected after enzymatic hydrolysis. Biochar from different pyrolysis temperatures (400–700 °C) and different dosages of the selected biochar (1–5%) were applied to remove colorants. The results showed that biochar had a good performance at a dosage of 2 w/w % on removal of colorant inhibitors. There was no negative effect observed during the subsequent fermentation. After optimization of fermentation media in shake flasks, the resultant succinic acid titer reached 19.6 g/L with a SA yield of 0.76 g/g, supplemented with 30 g/L tryptone. The in situ fibrous bed bioreactor (isFBB) can further improve SA titer, up to 28.8 g/L corresponding to a yield of 0.61 g/g without pH control. Furthermore, a shorter lag phase during succinic acid fermentation in isFBB was observed. It can be concluded that a novel textile waste-based biorefinery approach for succinic acid production aided by biochar sorption was successfully developed.

Intra-articular Treatment of Osteoarthritis with Diclofenac-Conjugated Polymer Reduces Inflammation and Pain.

The most common treatment for osteoarthritis is daily oral administration of a nonsteroidal anti-inflammatory drug such as diclofenac. This daily dosage regime is often associated with severe side effects. In this study, we explored the potential of utilizing a high molecular weight cross-linked polyurethane polymer covalently linked to diclofenac (C-DCF-PU) for intra-articular administration. We aim to exploit the advantages of local drug delivery by developing an implant with improved efficacy and reduced side effects. The polymer was synthesized from a diclofenac-functionalized monomer unit in a simple one-pot reaction, followed by cross-linking. In vitro drug release studies showed zero-order drug release for 4 days, followed by a gradual decline in drug release rate until diclofenac was depleted after 15 days. The cross-linked polymer was triturated to yield an injectable microgel formulation for administration. Whole animal fluorescence imaging of the rhodamine-labeled C-DCF-RH-PU showed good retention of the polymer in the knee joints of healthy rats, with approximately 30% of the injected dose still present 2 weeks post intra-articular administration. In a reactivation arthritis animal model, the C-DCF-RH-PU formulation reduced pain and significantly reduced inflammation after a short lag phase, showing that this drug delivery system warrants further development for long-term treatment of osteoarthritis with the benefit of reduced side effects.

In vitro analysis of genetically distinct Chlamydia pecorum isolates reveals key growth differences in mammalian epithelial and immune cells

Chlamydia (C.) pecorum is an obligate intracellular bacterium that infects and causes disease in a broad range of animal hosts. Molecular studies have revealed that this pathogen is genetically diverse with certain isolates linked to different disease outcomes. Limited in vitro or in vivo data exist to support these observations, further hampering efforts to improve our understanding of C. pecorum pathogenesis. In this study, we evaluated whether genetically distinct C. pecorum isolates (IPA, E58, 1710S, W73, JP-1-751) display different in vitro growth phenotypes in different mammalian epithelial and immune cells. In McCoy cells, shorter lag phases were observed for W73 and JP-1-751 isolates. Significantly smaller inclusions were observed for the naturally plasmid-free E58 isolate. C. pecorum isolates of bovine (E58) and ovine origin (IPA, W73, JP-1-751) grew faster in bovine cells compared to a porcine isolate (1710S). C. pecorum isolates could infect but appear not able to complete their developmental cycle in bovine peripheral neutrophil granulocytes. All isolates, except 1710S, could multiply in bovine monocyte-derived macrophages. These results reveal potentially important phenotypic differences that will help to understand the pathogenesis of C. pecorum in vivo and to identify C. pecorum virulence factors.

Effect of Sequential Acclimation to Various Carbon Sources on the Proteome of Acetobacter senegalensis LMG 23690T and Its Tolerance to Downstream Process Stresses.

Acetic acid bacteria are very vulnerable to environmental changes; hence, they should get acclimated to different kinds of stresses when they undergo downstream processing. In the present study, Acetobacter senegalensis LMG 23690T, a thermo-tolerant strain, was acclimated sequentially to different carbon sources including glucose (condition Glc), a mixture of glucose and ethanol (condition EtOH) and a mixture of glucose and acetic acid (condition GlcAA). Then, the effects of acclimation on the cell proteome profiles and some phenotypic characteristics such as growth in culture medium containing ethanol, and tolerance to freeze-drying process were evaluated. Based on the obtained results, despite the cells acclimated to Glc or EtOH conditions, 86% of acclimated cells to GlcAA condition were culturable and resumed growth with a short lag phase in a culture medium containing ethanol and acetic acid. Interestingly, if A. senegalensis LMG 23690T had been acclimated to condition GlcAA, 92% of cells exhibited active cellular dehydrogenases, and 59% of cells were culturable after freeze-drying process. Proteome profiles comparison by 2D-DiGE and MS analysis, revealed distinct physiological status between cells exposed to different acclimation treatments, possibly explaining the resulting diversity in phenotypic characteristics. Results of proteome analysis by 2D-DiGE also showed similarities between the differentially expressed proteins of acclimated cells to EtOH condition and the proteome of acclimated cells to GlcAA condition. Most of the differentially regulated proteins are involved in metabolism, folding, sorting, and degradation processes. In conclusion, acclimation under appropriate sub-lethal conditions can be used as a method to improve cell phenotypic characteristics such as viability, growth under certain conditions, and tolerance to downstream processes.

Evaluation of Growth of Toxigenic Strain of Aspergillus flavus on Turmeric-Based Media at Different Water Activities

Climatic conditions of the rain forest ecological zone of Nigeria favour the growth of Aspergillus flavus and subsequent aflatoxin production. This study was carried out to investigate the effect of water activity (0.85, 0.9, 0.95, 0.98 and 0.995 a ) on the lag phase prior to growth and mycelial growth of a toxigenic strain of A. flavus on turmeric-based media at 28±2oC after 12 days incubation period. Four different varieties; UT14, UT25, UT35 and UT46 obtained from National Root Crop Research Institute (NRCRI), Abia State and used in the preparation of the different media. A toxigenic strain of A. flavus isolated from turmeric in Port Harcourt was used in the experiment. The experiment was a 5 x 4 factorial laid out in completely randomized design (CRD), replicated three times. Results showed that regardless of the variety, no growth was observed at 0.85 a at 12 days of incubation. The shortest lag phase prior to growth was obtained at 0.995 a and the longest obtained at 0.90 a Optimal growth was observed at 0.98 a in three varieties (UT14, UT25and UT46), UT35 had marginal optimal growth at 0.995 a . Minimal growth of the A. flavus strain was obtained at 0.90 a at 28±2oC in all varieties. This result could be useful in the storage of turmeric, as this food product could be stored at moisture content of &lt; 85%.

The effect of epinephrine and norepinephrine on the growth and pathogenicity of Campylobacter jejuni

Campylobacter spp. is a leading cause of foodborne illness globally. The pathogen colonises the gastrointestinal tract of the host, where small concentrations of neuroendocrine hormones are also secreted. Epinephrine and norepinephrine are neuroendocrine hormones involved in the stress response that have been shown to promote the expression of virulence factors in pathogens including E. coli, Salmonella spp., and Campylobacter spp. In our study Campylobacter jejuni strains from human infection and broiler farms that were supplemented with epinephrine and norepinephrine showed increased growth characterised by shorter lag phases and higher maximum OD595, and enhanced pathogenicity characterised by increased motility, attachment to and invasion of Caco-2 cells. The data obtained suggests that host stress may promote C. jejuni proliferation and pathogenicity.

An Improved Method to Shorten Physiological Dormancy of Giant Ragweed (Ambrosia trifida) Seed

AbstractTimely results from whole-plant, herbicide-resistant weed screenings are crucial to heighten grower awareness. However, the high degree of physiological dormancy of giant ragweed (Ambrosia trifidaL.) seed exacerbates this process. The most effective methods for alleviating dormancy, to date, are either labor-intensive (embryo excision) or require several weeks (soil stratification). This research describes a conditioning process involving clipping and aeration of seed in water that is highly effective at alleviating dormancy and requires less skill and time compared with previous techniques.Ambrosia trifidaseeds were collected over 2 yr at two different collection timings (September 25, “early”; October 25, “late”), subjected to various treatments intended to release dormancy, and evaluated for emergence over 18 d in the greenhouse. The use of germination-promoting chemicals (ethephon, gibberellic acid, and thiourea) generally provided no increase in emergence compared with water and occasionally produced seedlings with abnormal growth unsuitable for further experimentation. Conditioning yielded between 30% and 33% emergence for both early and late collections of seeds with no afterripening period compared with 0% emergence for seeds imbibed in water. Following an 8-wk period of dry storage at 4 C, conditioning yielded nearly 80% emergence for both collection timings, while emergence of seeds imbibed in water was 10% and 27% for early and late collections, respectively. Soil stratification in moist soil for 8 wk at 4 C was the second most effective treatment, yielding 46% to 49% emergence across both collections. Parameters of the Weibull function further indicated the conditioning treatment had the fastest rate of emergence and shortest lag phase between planting and first emergence. Methods to germinateA. trifidawithout an afterripening period have previously been unsuccessful. Therefore, the seed-conditioning method outlined in this work will be useful in expediting the confirmation of herbicide-resistantA. trifidaincidences.