Nutrient modulation based process engineering strategy for improved butanol production from Clostridium acetobutylicum

The present study demonstrates a process engineering strategy to achieve high butanol titer and productivity from wild type Clostridium acetobutylicum MTCC 11274. In the first step, two different media were optimized with the objectives of maximizing the biomass and butanol productivity, respectively. In the next step, attributes of these two media compositions were integrated to design a two-stage fed-batch process which resulted in maximal butanol productivity of 0.55 g L⁻¹ h⁻¹ with titer of 13.1 g L⁻¹. Further, two-stage fed-batch process along with combinatorial use of magnesium limitation and calcium supplementation resulted in the highest butanol titer and productivity of 16.5 g L⁻¹ and 0.59 g L⁻¹ h⁻¹, respectively. Finally, integration of the process with gas stripping and modulation of feeding duration resulted in a cumulative butanol titer of 54.3 g L⁻¹ and productivity of 0.58 g L⁻¹ h⁻¹. The strategy opens up possibility of developing a viable butanol bioprocess. © 2019 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2771, 2019.     

Study of antimicrobial activity and root symbionts of Hemionitis arifolia

Antibacterial and antifungal activity of crude extract, alcoholic extract and extracted phenol from various parts of tropical pteridophyta, Hemionitis arifolia were tested by agar diffusion and tube dilution assay. Both the crude and alcoholic extracts of vegetative and reproductive leaves of H. arifolia showed considerable antibacterial activity against Gram negative test strain of Escherichia coli (MTCC-739). Extract from reproductive leaves also showed moderate antibacterial activity against Bacillus subtilis (MTCC-441) (Gram positive test strain) but didn’t show any antifungal activity against Candida albicans (MTCC-7353). Mycorrhizal and other symbiotic association with the root system of H. arifolia was studied and it is revealed that a number of mycorrhizal strains were present in both vegetative and reproductive form. Presence of Dark Septate Endophytic Fungi (DSF) was also detected.     

Heterogeneity in the cellular protein profiles ofClostridium botulinum types A and B

Summary Profiles of cellular proteins from 11 type A and 9 type B strains ofClostridium botulinum were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cellular protein profiles exhibited considerable heterogeneity among strains of the same biotype, as well as among strains of different biotypes. This study also demonstrated the reliability and usefulness of this rapid and inexpensive procedure to determine the variation which may occur amongC. botulinum and related species.References to brand or firm names do not constitute endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned.     

Efficient refolding and functional characterization of PfAMA1(DI+DII) expressed in E. coli

Apical membrane antigen 1 (AMA1) is a surface protein of Plasmodium sp. that plays a crucial role in forming moving junction (MJ) during the invasion of human red blood cells. The obligatory presence of AMA1 in the parasite lifecycle designates this protein as a potential vaccine candidate and an essential target for the development of novel peptide or protein therapeutics. However, due to multiple cysteine residues in the protein sequence, attaining the native fold with correct disulfide linkages during the refolding process after expression in bacteria has remained challenging for years. Although several approaches to obtain the refolded protein from bacterial expression have been reported previously, achieving high yield during refolding and proper functional validation of the expressed protein was lacking. We report here an improved method of refolding to obtain higher quantity of refolded protein. We have also validated the refolded protein's functional activity by evaluating the expressed AMA1 protein binding with a known inhibitory peptide, rhoptry neck protein 2 (RON2), using surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC).     

Peptides That Bind Specifically to an Antibody from a Chronic Lymphocytic Leukemia Clone Expressing Unmutated Immunoglobulin Variable Region Genes

Chronic lymphocytic leukemia (CLL) is a clonal disease of a subset of human B lymphocytes. Although the cause of the disease is unknown, its development and evolution appear to be promoted by signals delivered when B-cell receptors (BCRs) engage (auto)antigens. Here, using a peptide phage display library of enhanced size and diverse composition, we examined the binding specificity of a recombinant monoclonal antibody (mAb) constructed with the heavy chain and light chain variable domains of a CLL BCR that does not exhibit somatic mutations. As determined by testing the peptides identified in the selected peptide phage pool, this CLL-associated unmutated mAb bound a diverse set of sequences, some of which clustered in families based on amino acid sequence. Synthesis of these peptides and characterization of binding with the CLL-associated mAb revealed that mAb-peptide interactions were generally specific. Moreover, the mAb-peptide interactions were of lower affinities (micromolar K_D), as measured by surface plasmon resonance, than those observed with a CLL mAb containing somatic mutations (nanomolar K_D) and with immunoglobulin heavy chain variable (IGHV)-mutated antibodies selected by environmental antigens. This information may be of value in identifying and targeting B lymphocytes expressing specific BCRs in CLL patients and healthy subjects with monoclonal B lymphocytosis.     

Commentary on: Calpain-2 participates in the process of calpain-1 inactivation

Calpain belongs to the calcium-dependent non-lysosomal cysteine protease. Calpain-1 (C1) and calpain-2 (C2) expression are ubiquitous in mammals and an important mediator of the action of calcium. Specific substrate cleavage by C1 and C2 is critical for several calcium-dependent cellular pathways including neuronal function, muscle contraction, signal transduction, cell differentiation, proliferation, and apoptosis. Research suggests that C1 and C2 perform similar functions due to their structurally highly similar isoforms. Increasing evidence suggests that C1 and C2 carry out their specific function in vivo. A recent paper published by Shinkai-Ouchi et al. (Bioscience Reports (2020) 40, DOI: 10.1042/BSR20200552) elucidated the mechanism to differentiate the function of each calpain with respect to the efficiency and longevity for proteolysis after activation. Further, the study represented that C1 and C2 do not synergistically perform their work in vitro. On the other hand, the activity of C1 is reduced in presence of C2. This insight establishes the platform for future studies to examine how C2 regulates the C1 for substrate proteolysis.     

Differing myocardial response to a single session of hemodialysis in end-stage renal disease with and without type 2 diabetes mellitus and coronary artery disease

The ninth edition of the congress of the European Association of Echocardiography (EAE) (former working group of Echocardiography) held in Florence has just finished with a great success of participant attendance (2.842) and abstract submissions. Hot topics at EuroEcho 9 were: 1-live 3-dimensional echocardiography and surgical decision making; in pediatric cardiology; in resynchronization therapy 2- stress echocardiography beyond wall motion: from valve diseases to contractility to coronary flow reserve to diastolic function; 3- pulmonary cardiogenic interstitial thickening recognized by ultrasonic lung comets; 4- the "proven clinical inefficacy" of the many technologies sold as breakthrough: color kinesis, tissue characterization, strain rate, tissue Doppler, applied to stress echocardiography.