PRODUCTION AND CHARACTERIZATION OF ECONOMICAL BACTERIAL CELLULOSE

The present study investigates the economical production of bacterial cellulose (BC) by Gluconacetobacter subsp. Xylinus (ATCC 10245) in 250 ml Erlenmeyer flasks cultivated under static conditions. The fermentation media used contained food industrial by-product liquors, such as black strap molasses solution and corn steep liquor (CSL), which represents some of the most economical carbon and nitrogen sources. However, because of the presence of undesirable components in molasses (such as coloring substances, heavy metals, and other compounds) that may act as inhibitors, and in order to eliminate them, crude molasses has been treated with an acid, as an attempt to increase BC productivity. The amount of BC produced using these carbon and nitrogen sources was determined and compared to that produced using previously reported fermentation media. The characterizations of the bacterial cellulose (BC) pellicles obtained using either conventional or by-product media were studied by thermal and spectral techniques and compared to those of plant-derived cellulose such as cotton linter, viscose pulp, and microcrystalline cellulose

Applications of Plackett–Burman and Central Composite Design for the Optimization of Novel Brevundimonas diminuta KT277492 Chitinase Production, Investigation of its Antifungal Activity

ABSTRACT Biological control strategy which can damage chitin, a vital component of pathogenic fungi and arthropods promises a safe solution for many fungal problems. And it’s more favorable than chemicals which increase health risks and environmental problems. Thus, the chitinase producers appear potential candidates of biological control of pathogenic fungi. Brevundimonus diminuta KT277492 is a new isolate that has been isolated recently from Egyptian soil. Significant factors that affecting the chitinase enzyme production were studied and optimized using Plackett-Burman and Response Surface Methodology (RSM). As a result, maximum production of chitinase enzyme was 832.87 IUL-1, this result presented about 8.767-fold increase in the enzyme production. In the last phase of the study, partially purified chitinase enzyme obtained from B. diminuta KT277492 was tested against two pathogenic fungi and the results showed good inhibitory activity against A. alternata and F. solani with IZD of 31±0.25 and 25±0.91 mm respectively. Finally, obtained results indicated the value of optimization process and the optimized chitinase enzyme could be an excellent choice in application of food and biotechnology as a biofungicide. This reflects the necessity of studying the characteristics and kinetics of the enzyme in the forthcoming study

Extra-epitopic hepatitis C virus polymorphisms confer resistance to broadly neutralizing antibodies by modulating binding to scavenger receptor B1

<div><p>Broadly-neutralizing monoclonal antibodies (bNAbs) may guide vaccine development for highly variable viruses including hepatitis C virus (HCV), since they target conserved viral epitopes that could serve as vaccine antigens. However, HCV resistance to bNAbs could reduce the efficacy of a vaccine. HC33.4 and AR4A are two of the most potent anti-HCV human bNAbs characterized to date, binding to highly conserved epitopes near the amino- and carboxy-terminus of HCV envelope (E2) protein, respectively. Given their distinct epitopes, it was surprising that these bNAbs showed similar neutralization profiles across a panel of natural HCV isolates, suggesting that some viral polymorphisms may confer resistance to both bNAbs. To investigate this resistance, we developed a large, diverse panel of natural HCV envelope variants and a novel computational method to identify bNAb resistance polymorphisms in envelope proteins (E1 and E2). By measuring neutralization of a panel of HCV pseudoparticles by 10 μg/mL of each bNAb, we identified E1E2 variants with resistance to one or both bNAbs, despite 100% conservation of the AR4A binding epitope across the panel. We discovered polymorphisms outside of either binding epitope that modulate resistance to both bNAbs by altering E2 binding to the HCV co-receptor, scavenger receptor B1 (SR-B1). This study is focused on a mode of neutralization escape not addressed by conventional analysis of epitope conservation, highlighting the contribution of extra-epitopic polymorphisms to bNAb resistance and presenting a novel mechanism by which HCV might persist even in the face of an antibody response targeting multiple conserved epitopes.</p></div

Construction of an HCV E1E2 panel for neutralizing antibody breadth testing and sequence prediction of neutralizing antibody resistance polymorphisms.

<p>(<b>A</b>) Number of different amino acids present at each position in the 113 variant E1E2 panel (blue line). Regions spanning E1, hypervariable region 1 (HVR1), and E2 are indicated. For comparison, black line in the upper plot shows the number amino acids represented at each position by at least 5% of the sequences in a reference panel of 643 HCV genotype 1 isolates from GenBank. Gray line in the lower plot shows the number amino acids represented at each position by at least one sequence in the reference panel of 634 HCV genotype 1 isolates from GenBank. (<b>B</b>) Variation in the E1E2 panel of known critical binding residues for HC33.4 and AR4A. Numbers indicate the polyprotein position of each amino acid. Height of each amino acid is proportional to its frequency in the panel. Letters are standard IUPAC amino acid abbreviations. (<b>C</b>) Phylogenetic tree of E1E2 amino acid sequences of the 113 variant panel, determined by maximum likelihood, shown with the distances drawn to scale. Clones are colored according to their sensitivity to neutralization: ln(Fraction Unaffected (F_u) by 10 μg/mL of HC33.4 (left) and AR4A (right)). F_u is infection in the presence of 10 μg/mL of bNAb/infection in the presence of nonspecific human IgG.</p

Comparison of F_u of HCVpp segregated by the amino acid present at positions predicted by SNAPR to influence bNAb resistance.

<p>Boxplots showing the F_u values for all isolates grouped by amino acid present at the indicated position in the presence of HC33.4 (<b>A</b>) and AR4A (<b>B</b>) in order of their polyprotein position. Each data point indicates the mean F_u of an individual HCVpp, measured in duplicate. Boxes are interquartile range, and horizontal lines are medians. The eight positions with lowest SNAPR-values for each bNAb are shown. The letters shown are standard IUPAC amino acid abbreviations. F_u of HCVpp with the indicated polymorphisms were compared by Wilcoxon rank-sum test. (*, p<0.05).</p