http://localhost:8080/xmlui/handle/123456789/2068 Tue, 19 May 2026 01:29:09 GMT 2026-05-19T01:29:09Z http://localhost:8080/xmlui/handle/123456789/4836 Engineering of Corynebacterium glutamicum for xylitol production from lignocellulosic pentose sugars Dhar, K S; Wendisch, V F; Nampoothiri, K M Xylitol is a non-fermentable sugar alcohol used as sweetener. Corynebacterium glutamicum ATCC13032 was metabolically engineered for xylitol production from the lignocellulosic pentose sugars xylose and arabinose. Direct conversion of xylose to xylitol was achieved through the heterologous expression of NAD(P)H-dependent xylose reductase (xr) gene from Rhodotorula mucilaginosa. Xylitol synthesis from arabinose was attained through polycistronic expression of l-arabinose isomerase (araA), d-psicose 3 epimerase (dpe) and l-xylulose reductase (lxr) genes from Escherichia coli, Agrobacterium tumefaciens and Mycobacterium smegmatis, respectively. Expression of xr and the synthetic araA-dpe-lxr operon under the control of IPTG-inducible Ptac promoter enabled production of xylitol from both xylose and arabinose in the mineral (CGXII) medium with glucose as carbon source. Additional expression of a pentose transporter (araTF) gene enhanced xylitol production by about four-fold compared to the parent strain. The constructed strain Cg-ax3 produced 6.7 ± 0.4 g/L of xylitol in batch fermentations and 31 ± 0.5 g/L of xylitol in fed-batch fermentations with a specific productivity of 0.28 ± 0.05 g/g cdw/h. The strain Cg-ax3 was also validated for xylitol production from pentose rich, acid pre-treated liquor of sorghum stover (SAPL) and the results were comparable in both SAPL (27 ± 0.3 g/L) and mineral medium (31 ± 0.5 g/L). Wed, 20 Jul 2016 00:00:00 GMT http://localhost:8080/xmlui/handle/123456789/4836 2016-07-20T00:00:00Z http://localhost:8080/xmlui/handle/123456789/4834 Harvesting of microalgal biomass: Efficient method for flocculation through pH modulation Ummalyma, S B; Mathew, A K; Pandey, A; Sukumaran, R K Harvesting of the micro alga Chlorococcum sp. R-AP13 through autoflocculation, chemical flocculants or by change in medium pH was evaluated. Surface charge of algal cells changed in response to the method used and affected flocculation efficiency. While aluminum sulfate and FeCl3 supported 87% and 92% efficiency, auto flocculation could recover 75% of biomass in 10 min. Maximum efficiency (94%) was obtained with change in medium pH from 8.5 to 12.0 achieved through addition of 40 mg l−1 of NaOH. Since high concentrations of FeCl3 and AlSO4 were toxic to the cells, flocculation induced by pH change may be considered the most effective strategy. Residual medium after flocculation could be reused efficiently for algal cultivation, minimizing the demand for fresh water. Mon, 01 Aug 2016 00:00:00 GMT http://localhost:8080/xmlui/handle/123456789/4834 2016-08-01T00:00:00Z http://localhost:8080/xmlui/handle/123456789/4831 Influence of aliovalent cation substitutions on the optical properties of In2Cu2O5 system Divya, S; Rao, P P; Sameera, S; Raj, A K V The influence of aliovalent cation substitutions in In2Cu2O5 system on the optical properties has been investigated through the powder X-ray diffraction coupled with Rietveld analysis, UV–vis–NIR spectroscopy, scanning electron microscope attached with energy dispersive spectrometer. The aliovalent cation substitution affected the optical absorption of the system distinctly as the counter cation substitution of Sc3+ influences the crystal field environment of Cu2+ ions more dominantly than that of the direct substitution of Zn2+ ions. Consequently this allowed the red shift of the absorption edge pronouncedly in the case of Sc3+ substituted samples than that in the Zn2+ substituted ones. The key factor responsible for achieving the larger red shift in Sc3+ substituted sample is due to increased anion polarizability. The assessments of crystal field and tetragonality parameters corroborate the variation of charge transfer energies for the aliovalent cation substitutions. The modified absorption properties translated in enhancing the green chromacity and reflectance of the In2Cu2O5 system even better than the commercially available chromium oxide green (Cr2O3). Tue, 01 Nov 2016 00:00:00 GMT http://localhost:8080/xmlui/handle/123456789/4831 2016-11-01T00:00:00Z http://localhost:8080/xmlui/handle/123456789/4830 Microbial assisted High Impact Polystyrene (HIPS) degradation Mohan, A J; Sekhar, V C; Bhaskar, T; Nampoothiri, K M The efficacy of newly isolated Pseudomonas and Bacillus strains to degrade brominated High Impact Polystyrene (HIPS) was investigated. Viability of these cultures while using e-plastic as sole carbon source was validated through Triphenyl Tetrazolium Chloride (TTC). Four days incubation of HIPS emulsion with Bacillus spp. showed 94% reduction in turbidity and was 97% with Pseudomonas spp. Confirmation of degradation was concluded by HPLC, NMR, FTIR, TGA and weight loss analysis. NMR spectra of the degraded film revealed the formation of aliphatic carbon chain with bromine and its release. FTIR analysis of the samples showed a reduction in Csingle bondH, Cdouble bondO and Cdouble bondN groups. Surface changes in the brominated HIPS film was visualized through SEM analysis. Degradation with Bacillus spp showed a weight loss of 23% (w/w) of HIPS film in 30 days. Mon, 01 Aug 2016 00:00:00 GMT http://localhost:8080/xmlui/handle/123456789/4830 2016-08-01T00:00:00Z