Revista de bioprocesamiento y biotecnologías

Over the last two decades, most of Italian vines have produced grapes with higher sugar to total acid ratios, greater concentrations of phenols and aromatic compounds and greater potential wine quality. As a consequence, the musts obtained by these grapes are more difficult to process because of the risk of slowing or stuck of fermentation. With the aim of describing the time evolution of the sugars bioconversion during alcoholic fermentation, the kinetics of the D-glucose and D-fructose degradations, promoted by two yeast strains (Saccharomyces cerevisiae (strain C) e Saccharomyces bayanus (strain B)), was investigated using synthetic media, added or not with ethanol. The concentrations of both the substrates and the products of the sugars conversions, as well as the number of viable cells of yeasts, were determined as a function of the alcoholic fermentation time and the related kinetics constants determined. If the reaction medium contained high concentrations of both glucose and fructose, the strains showed significant different fermentatory ability. In these conditions a stuck of fermentation occurred and the remaining sugar was only fructose (strain C) or prevailing fructose (strain B). If the reaction medium contained only glucose as substrate, the strain C seemed more efficient while the kinetics behavior changed completely in presence of only fructose. On the basis of the information collected using this kinetic approach, it would be possible to develop technical data sheets, specific for each yeast strain, useful to choose the optimal microbial strain as a function of the different operative conditions. Moreover the kinetic constant of hexose conversion could be adopted as bio-markers in selection and breeding of wine yeast strains having a lower tendency for sluggish fructose fermentation.

The characterisation of biosorption by Schizosaccharomyces pombe of Co(II) was done under varying experimental conditions including pH, temperature, initial metal concentration and biosorbent dose. Optimum pH was found to be 5.0 with optimal biosorbent dose for highest adsorption capacity at 1.0 g L^-1. Higher initial metal concentrations helped enhance q_e slightly with the highest value, 2.7 mg g^-1, being achieved at 25°C and 50 mg L^-1 initial Co(II). Temkin isotherm model showed the best statistical fit for equilibrium data while Freundlich isotherm model exhibited thermodynamic consistency. Pseudo-first order kinetics was found to represent Co(II) biosorption. Increasing ΔG⁰ values calculated with respect to higher operational temperatures were in agreement with kinetic profiling simulations whereby higher temperatures were found to be less favourable. Overall efficiency of S. pombe as a biosorbent for Co(II) was found to be significantly less than Ni(II), for this reason it can be regarded as a potential bioseparation agent for aqueous mixtures containing both Co(II) and Ni(II).

The SSF lipase production from Penicillium simplicissimum using an agro industrial residue and the biosurfactant from Pseudomonas aeruginosa were employed for a combined pre-treatment of wastewater from poultry processing industry. During the hydrolysis step of the wastewater fat better results were obtained at 34°C with biosurfactant 0.4% (v/v) and liquid enzyme preparation 6.2% (v/v) or at 46°C with biosurfactant 0.1% (v/v) and liquid enzyme preparation 3.8% (v/v). The pre-hydrolysis in two different conditions of enzyme and biosurfactant concentrations at 34°C and posterior anaerobic treatment allowed the COD removal and methane production, while the no hydrolyzed wastewater besides the COD removal, did not show methane production. Those results suggest the importance and efficiency of the pre-treatment with home-made lipases and biosurfactant during the high fat content wastewater pre-treatment.

Biologics manufacturing requires the clearance of Host Cell Proteins (HCPs) from recombinant therapeutic protein to acceptable low levels to ensure product purity and patient safety. To ensure adequate removal, a highly sensitive method, commonly in the form of Enzyme-Linked Immunosorbent Assay (ELISA), is necessary to quantify the HCPs amount in process intermediates and drug substance. We report the development of a chemiluminescent detection based ELISA (luminescent ELISA) in lieu of previously used colorimetric method (colorimetric ELISA) to improve assay sensitivity for the quantification of Chinese Hamster Ovary (CHO) HCPs in a monoclonal antibody product (mAb-A). For luminescent ELISA, Pierce Supersignal ELISA Femto was chosen as the substrate to replace colorimetric substrate TMB. The assay performance of luminescent and colorimetric ELISA was directly compared side-by-side. Our data show that luminescent ELISA has better signal/background ratio, broader linear range over logarithmic scales, and better linearity within the same linear range than colorimetric ELISA. Luminescent ELISA also demonstrates better lowend linearity, greater accuracy and precision. In addition, the Limit of Detection (LOD) and Limit of Quantification (LOQ) are significantly improved with luminescent ELISA as compared to colorimetric ELISA. In summary, luminescent ELISA is a more sensitive method and demonstrates superiority over colorimetric method for CHO HCP quantification.

Waste residual molasses, a non-edible portion produced during the processing of sugarcane juice for the preparation of molasses, may be an alternative low-cost renewable substrate to the pricey food-grade molasses for xanthan production. Systematic strategies were applied to improve xanthan production with a newly isolated indigenous strain Xanthomonas campestris originated from Tezpur, Assam. Analyses with TLC, HPLC and FTIR show that the polymer consisted mainly of glucose, galactose and glucornic acid but showed no evidence of xylose, arabinose or glycoprotein in the polysaccharide. The isolated xanthan exhibited all the required physico-chemical characteristics and were examined by using TGA, DSC, XRD and SEM. Maximum concentration of xanthan was observed after 24h of incubation of the culture media, pH 7 at 28°C with 200 rpm. The viscosity of xanthan was found to be stable over a wide range of pH, reduced with the increase in temperature and raised at the higher xanthan concentration. The results obtained in the present investigation are noteworthy for the possible xanthan production from low-cost waste residual molasses at an industrial level.

The fermentations induced by the utilization of sourdough in bread-making, are able to enhance the qualitative properties of the final dough, improving its volume, texture and flavor, so to obtain a bread characterized by high qualitative properties and able to retard its staling process. In particular the working conditions adopted can deeply affect the ratio occurring between the populations of lactic acid bacteria and alcoholic yeasts of the sourdough and then also the productions of the related metabolites, which deeply affect the organoleptic characteristics and then also the quality of the final bread. The effect induced on the microbial and chemical composition of the sourdough by different values of the storage temperature utilized (13, 19 and 27°C) between two successive refreshes (~ 24 hours), was evaluated to put in evidence the different sensory characteristics assumed by the corresponding breads. The sensory profiles of the obtained breads evaluated by the descriptive analyses, were carried on by a panel of trained assessors using a sensorial sheet specifically developed for this purpose and characterized by unstructured graphical intensity scales; the reliability of judgments obtained was evaluated by statistical analysis. So it was possible to put in evidence the high degree of correlation occurring among microbiological and chemical data of the sourdoughs and the sensorial characteristics of the corresponding bread. Among the three storage temperatures of the sourdough, 19°C appears to be able to ensure the best organoleptic characteristics to this particular bread.