Thermal, spectroscopic, SEM and rheological datasets of native and quaternized guar gum.

The manuscript reports TGA, DTA, SEM and NMR datasets of native and quaternized guar gum as a tool for their characterization. The TGA and DTA data was acquired in temperature range 35-500 °C. Based on the TGA experimental values, activation energy plots were drawn to study the stability of native and quaternized polysaccharides (Cai and Bi, 2008 [1]). The data demonstrates the thermal behaviour of quaternized guar gum vis-a-vis native guar gum. The surface morphology of native and quaternized galactomannan was represented by SEM imaging. The 1H-1H COSY was acquired to understand structural changes by quaternization. The rheological measurements of native and modified products were carried out to obtain the viscosity profile of the respective samples. The datasets support the research article 'Synthesis of quaternized guar gum using Taguchi L (16) orthogonal array' (Tyagi et al., 2020 [2]).

Synthesis of quaternised guar gum using Taguchi L(16) orthogonal array.

Quaternised polysaccharides have diverse applications due to introduction of quaternary ammonium groups in the biopolymer. In the present study, quaternization of guar gum was carried out by adopting the Taguchi's approach of robust design of experiments for optimizing the levels of the factors to obtain quaternized guar gum with higher DS. The methodology employed far less number of experiments than the classical method which necessitates higher number of chemical reactions to achieve the required derivatisation. The application of Taguchi's L16 (45) orthogonal array resulted in DS of 0.49. The optimized experimental levels were 3.24 mol/AGU of NaOH and 2.04 mol/AGU of CHPTAC for 2 h at 30 °C keeping the gum: liquor ratio 1:20. The study established that Taguchi methodology provided a statistically sound and green approach for optimization of reaction conditions. The modified products were characterised by FTIR, 1H-NMR, 13C-NMR, DEPT-135, HSQC and HMBC spectroscopic methods.

Antimicrobial Susceptibility and SOS-Dependent Increase in Mutation Frequency Are Impacted by Escherichia coli Topoisomerase I C-Terminal Point Mutation.

Topoisomerase functions are required in all organisms for many vital cellular processes, including transcription elongation. The C terminus domains (CTD) of Escherichia coli topoisomerase I interact directly with RNA polymerase to remove transcription-driven negative supercoiling behind the RNA polymerase complex. This interaction prevents inhibition of transcription elongation from hypernegative supercoiling and R-loop accumulation. The physiological function of bacterial topoisomerase I in transcription is especially important for a rapid network response to an antibiotic challenge. In this study, Escherichia coli with a topA66 single nucleotide deletion mutation, which results in a frameshift in the TopA CTD, was shown to exhibit increased sensitivity to trimethoprim and quinolone antimicrobials. The topoisomerase I-RNA polymerase interaction and the SOS response to the antimicrobial agents were found to be significantly reduced by this topA66 mutation. Consequently, the mutation frequency measured by rifampin selection following SOS induction was diminished in the topA66 mutant. The increased antibiotic sensitivity for the topA66 mutant can be reversed by the expression of recombinant E. coli topoisomerase I but not by the expression of recombinant Mycobacterium tuberculosis topoisomerase I that has a nonhomologous CTD even though the recombinant M. tuberculosis topoisomerase I can restore most of the plasmid DNA linking number deficiency caused by the topA66 mutation. Direct interactions of E. coli topoisomerase I as part of transcription complexes are likely to be required for the rapid network response to an antibiotic challenge. Inhibitors of bacterial topoisomerase I functions and interactions may sensitize pathogens to antibiotic treatment and limit the mutagenic response.

Development of a loop-mediated isothermal amplification assay for rapid detection of BK virus.

Loop-mediated isothermal amplification (LAMP) is a novel method for rapid amplification of DNA. Its advantages include rapidity and minimal equipment requirement. The LAMP assay was developed for BK virus (BKV), which is a leading cause of morbidity in renal transplant recipients. The characteristics of the assay, including its specificity and sensitivity, were evaluated. BKV LAMP was performed using various incubation times with a variety of specimens, including unprocessed urine and plasma samples. A ladder pattern on gel electrophoresis, typical of successful LAMP reactions, was observed specifically only for BKV and not for other viruses. The sensitivity of the assay with 1 h of incubation was 100 copies/tube of a cloned BKV fragment. Additionally, a positive reaction was visually ascertained by a simple color reaction using SYBR green dye. BKV LAMP was also successful for urine and plasma specimens without the need for DNA extraction. Due to its simplicity and specificity, the LAMP assay can potentially be developed for "point of care" screening of BKV.