Low oxygen arrests Babesia duncani schizonts and leads to increased drug susceptibilities in hamster erythrocytes

We studied the effect of oxygen concentrations on the in vitro growth and drug susceptibility of Babesia duncani. We found that the growth of B. duncani required high level oxygen and the culture condition at ambient aerobic condition (21% O2) was optimal. Compared with ambient air, our results further showed that low oxygen (6-16%) could arrest B. duncani schizonts and lead to high susceptibilities to antiparasitic drugs atovaquone, pyrimethamine, quinine, and chloroquine at certain concentrations in vitro. Drug susceptibilities of other Babesia spp impacted by O2 levels need to be studied in the future, and this study indicates that culturing conditions of Babesia spp should be considered and reestablished for generating more comparable and reliable results in drug research in the future.Graphical abstractHighlightsThe in vitro growth of B. duncani requires high level oxygen and the culture condition of 5% CO2 ambient air is optimalLow level oxygen results B. duncani in low growth rate and high schizont ratio in vitroCompared with 5% CO2 ambient air, in vitro drug susceptibilities of B. duncani can be significantly increased when cultured in microaerobic condition

Effects of Electromagnetic Fields Exposure on the Production of Nanosized Magnetosome, Elimination of Free Radicals and Antioxidant Defense Systems in Magnetospirillum gryphiswaldense MSR-1

Magnetotactic bacteria integrated magnetosomes, which are unique organelles that contain nanosized crystals of biogenic magnetic iron minerals with the ability to respond to the external magnetic fields. The biogenic magnetic nanoparticles (magnetosomes) show high biocompatibility in medical applications especially as scavengers to eliminate intracellular reactive oxygen species. The aim of this study was to highlight the impact of magnetosome formation and antioxidant systems in the suppression of oxidative stress on the magnetotactic bacteria cells. To assess the changes in ROS levels under different magnetic field intensity conditions, cells were cultured under the microaerobic condition in medium containing the high and low intensity of magnetic field. Treatment of magnetic field with an intensity of 500 mT during 50 hours bionormalization process of magnetotactic bacteria increased the antioxidant enzyme activity for eliminating of free radicals by 64%. We concluded that magnetosomes production plays an important role in decreasing or eliminating ROS. This is the first study to demonstrate that the magnetic field assisted magnetosome formation and antioxidants defense systems inMagnetospirillum gryphiswaldenseMSR-1.

Bioremediation of synthetic fatliquors under microaerobic condition

Synthetic fatliquors are useful as a fatliquoring agent, flotation agent and emulsifying agent in a wide range of industrial applications such as leather, pharmacy and farm chemicals. These fatliquors remain recalcitrant to natural biota in existing treatment plants. In the present study, the isolated microaerophilic Serratia sp. HA1 strain CSMB3 is capable of utilizing structurally different fatliquors as the sole substrate for their growth under microaerobic conditions. Degradation of vegetable fatliquors was observed from 95 to 97% in terms of lipids, with the production of lipase at 72 h. Degradation of synthetic fatliquors was observed in terms of chemical oxygen demand from 85% to a minimum of 25%. It is in the order of sulfited/sulfated fatliquors > sulfochlorinated fatliquors > chlorinated fatliquors. A thin layer chromatography chromatogram confirmed the degradation of non polar fatliquor to polar compounds. Production of the red pigment prodigiosin in synthetic fatliquors enhanced the growth of the isolate. Fourier transform infrared spectroscopy (FTIR) confirmed the bioremediation of sulfochlorinated fatliquor into lipids and fatty acids and gas chromatography–mass spectrometry (GC-MS) results confirmed that alcohols and esters are the final end products. Thus the isolated strain CSMB3 may be used in the treatment of wastewaters containing vegetable and synthetic fatliquors.

Overproduction of Indole-3-Acetic Acid in Free-Living Rhizobia Induces Transcriptional Changes Resembling Those Occurring in Nodule Bacteroids

Free-living bacteria grown under aerobic conditions were used to investigate, by next-generation RNA sequencing analysis, the transcriptional profiles of Sinorhizobium meliloti wild-type 1021 and its derivative, RD64, overproducing the main auxin indole-3-acetic acid (IAA). Among the upregulated genes in RD64 cells, we detected the main nitrogen-fixation regulator fixJ, the two intermediate regulators fixK and nifA, and several other genes known to be FixJ targets. The gene coding for the sigma factor RpoH1 and other genes involved in stress response, regulated in a RpoH1-dependent manner in S. meliloti, were also induced in RD64 cells. Under microaerobic condition, quantitative real-time polymerase chain reaction analysis revealed that the genes fixJL and nifA were up-regulated in RD64 cells as compared with 1021 cells. This work provided evidence that the overexpression of IAA in S. meliloti free-living cells induced many of the transcriptional changes that normally occur in nitrogen-fixing root nodule.

Metabolic Engineering ofEscherichia colifor Poly(3-hydroxybutyrate) Production under Microaerobic Condition

The alcohol dehydrogenase promoterPadhEand mixed acid fermentation pathway deficient mutants ofEscherichia coliwere employed to produce poly(3-hydroxybutyrate) (P3HB) under microaerobic condition. TheE. colimutant withackA-pta, poxB, ldhA, andadhEdeletions accumulated 0.67 g/L P3HB, up to 78.84% of cell dry weight in tube cultivation. The deletion of pyruvate formate-lyase genepflBdrastically decreased P3HB production and P3HB content to 0.09 g/L and 24.44%, respectively. OverexpressingpflBvia the plasmid in its knocked out mutant restored cell growth and P3HB accumulation, indicating the importance of the pyruvate formate-lyase in microaerobic carbon metabolism. The engineeredE. coliBWapld (pWYC09) produced 5.00 g/L P3HB from 16.50 g/L glucose in 24 h batch fermentation, and P3HB production yield from glucose was 0.30 g/g, which reached up to 63% of maximal theoretical yield.

Potential ProbioticEscherichia coli16 Harboring theVitreoscillaHemoglobin Gene Improves Gastrointestinal Tract Colonization and Ameliorates Carbon Tetrachloride Induced Hepatotoxicity in Rats

The present study describes the beneficial effects of potential probioticE. coli16 (pUC8:16gfp) expressingVitreoscillahemoglobin (vgb) gene, associated with bacterial respiration under microaerobic condition, on gastrointestinal (GI) colonization and its antioxidant activity on carbon tetrachloride (CCl4) induced toxicity in Charles Foster rats.In vitro, catalase activity inE. coli16 (pUC8:16gfp) was 1.8 times higher compared toE. coli16 (pUC-gfp) control.In vivo,E. coli16 (pUC8:16gfp) not only was recovered in the fecal matter after 70 days of oral administration but also retained antibacterial activities, whereasE. coli16 (pUC-gfp) was not detected. Oral administration of 200 and 500 μL/kg body weight of CCl4to rats at weekly interval resulted in elevated serum glutamyl pyruvate transaminase (SGPT) and serum glutamyl oxalacetate transaminase (SGOT) levels compared to controls. Rats prefed withE. coli16 (pUC8:16gfp) demonstrated near to normal levels for SGPT and SGOT, whereas the liver homogenate catalase activity was significantly increased compared to CCl4treated rats. Thus, pUC8:16gfpplasmid encodingvgbimproved the growth and GI tract colonization ofE. coli16. In addition, it also enhanced catalase activity in rats harboringE. coli16 (pUC8:16gfp), thereby preventing the absorption of CCl4to GI tract.