Production and characterization of value-added biorenewable chemicals

Nisin is the only FDA-approved bacteriocin with a GRAS (Generally Regarded as Safe) status, used as a biopreservative/shelf-life extender in foods and many other products including pharmaceutical, veterinary and health care products. It is produced commercially by fermentation of a milk-based medium, using strains of Lactococcus lactis subsp. lactis. However, being a dairy-based product requires its labeling since milk is an allergen. Also, since its high production cost is mainly dominated by its medium costs, an emerging trend has been observed with a growing number of studies aimed at finding alternative, non-dairy and preferably non-allergen-based substrates. In order to cut costs, and to also be an environmentally friendly approach, several of these substrates have been sourced from agriculture or aquaculture-based waste streams. The review included in this dissertation highlights the advantages of value-addition to waste and the promising potentials of some of these low-value nutritive sources for the production of high-value nisin. An in-depth study of soy whey (SW) as a non-dairy, nisin fermentation feedstock was performed using Lactococcus lactis. Results indicated that SW was able to produce equivalent biomass and nisin yields (2.18g/L and 619mg/L), as compared to the commercial medium, de Man-Rogosa-Sharpe (MRS) broth (2.17g/L and 672mg/L, respectively), without the need for external nutrient supplementation. This indicated the nutritive qualities of this co-product stream in being able to support the growth of a fastidious bacterial culture. The success of SW as a bacterial growth medium motivated the second study which focused on growing the oleaginous algal strain Chlorella vulgaris under mixotrophic and heterotrophic culture conditions. Microalgae are cultivated in large scale for several commercially important products among which algal lipids have gained increasing interest due to their use as biodiesel feedstock as well as a source of essential fatty acids with neutraceutical value. Photoautotrophic algal cultivation suffers from low growth rates while heterotrophic/mixotrophic modes have high media costs. In order to boost algal lipid production with lower media costs, two co-product streams, SW and thin stillage (TS) were tested as growth substrates. TS is a high-organic strength co-product generated from the dry-grind corn-ethanol industry. Traditional use of TS involves an energy-intensive concentration process to form syrup which finally ends up as animal feed in Distillers\u27 Dried Grains with Solubles (DDGS). The cost-effectiveness and success of the corn-ethanol industry is highly dependent on the value of its co-products. Therefore, in order to be an economically viable and an environmentally sustainable process, researching new avenues for value-addition to TS is very important. As per the results from the current study, biomass yields (dry basis, db) from TS, SW and a synthetic control medium-MBM (modified basal medium) after 4 days of incubation were 9.8, 6.3 and 8.0 g/L with oil contents at 43, 11, and 27 % (w/w) respectively. Polyunsaturated fatty acids (PUFAs) or essential FAs, were found to be highest in Chlorella-TSoil (56%), followed by 38% in Chlorella-SWoil and 31% in Chlorella-MBMoil. Therefore, mixotrophic cultivation of C. vulgaris in TS and SW produced high yields of both algal biomass and lipids at low cost, thus adding value to co-product streams and improving economic viability of algal cultivation. The high algal oil yields from TS motivated the third study involving the use of oleaginous fungal strain, Mucor circinelloides for its potential in adsorbing/assimilating the oil and nutrients present in TS, for the production of lipid and protein-rich fungal biomass. Fungal batch cultivation for 2 days using a 6-L airlift reactor led to a 92% increase in oil yield from TS, relative to the original oil content, with concomitant reduction in suspended solids and chemical oxygen demand (COD) in TS by 95% and 89% respectively. M. circinelloides, when grown on TS gave a biomass yield of 20 g/L (dry basis), with a lipid content of 46 % (dwb). The polyunsaturated fatty acids were 52% of the total lipids. Overall, fungal cultivation on TS produced a high-protein animal feed and high-value fungal oil, thus improving corn-ethanol process economics. The fourth study focused on employing the hurdle concept and developing more efficient antimicrobial systems by combining plant essential oils (EOs) with food-grade organic acids. The seven most active oils among the sixteen tested, were combined with five different organic acids and the antimicrobial interactions (synergistic/additive/antagonistic) were examined against food-related pathogens. Malic and citric acid were the most inhibitory acids which showed synergism with mountain savory, redistilled oregano (RO), and cinnamon oils against S.aureus 25923 and with cassia, RO, and cinnamon oils against E.coli 25922. The only synergistic EO-acid combination against C.albicans 10231 was lemon myrtle-citric acid

Optimally Convex Controller and Model Reduction for a Dynamic System

This paper presents analysis and design of a family of controllers based on numerical convex optimization for an aircraft pitch control system. A design method is proposed here to solve control system design problems in which a set of multiple closed loop performance specifications are simultaneously satisfied. The transfer matrix of the system is determined through the convex combination of the transfer matrices of the plant and the controllers. The present system with optimal convex controller has been tested for stability using Kharitonov’s Stability Criteria. The simulation deals here withthe problem of pitch control system of a BRAVO fighter aircraft which results in higher order close loop transfer function. So the order of the higher order transfer function is reduced to minimize the complexity of the system

Ultrasonication in Soy Processing for Enhanced Protein and Sugar Yields and Subsequent Bacterial Nisin Production

Soy protein recovery from hexane-defatted soybean flakes using conventional methods is generally low. Importantly, some tightly-bound sugar in the soy flakes ends up in soy protein, thereby deteriorating the usefulness and quality of soy protein as a food ingredient. This research investigated the use of high-power ultrasound prior to soy protein extraction to simultaneously enhance protein yield and facilitate more sugar release in soy whey. The nutrient-rich soy whey was then used as a cheap growth medium to produce high-value nisin using Lactococcus lactis subsp. lactis. A nisin sensitive organism Micrococcus luteus was used as an indicator organism for international unit determination of nisin production as compared to standard. Soy flakes and water was mixed at the ratio of 1:10 (w/w). The slurry was then sonicated for 15, 30, 60 and 120 sec at a frequency of 20 kHz. The ultrasonic amplitude was maintained at 84 µmpp (peak to peak amplitude in µm) for all sonication durations. The results showed that with ultrasound pretreatment, the protein yield improved as much as by 46% in soy extract and sugar release by 50% with respect to nonsonicated samples (control). To maximize nisin production from soy whey, different parameters, such as aeration/agitation and incubation period were optimized. Nisin production from standard medium, DeMan, Rogosa and Sharpe (MRS) and soy whey was tested and compared. Maximum nisin production was achieved in stationary conditions and showed a continuous increase in yield till 48h of incubation (incubation period beyond that was not tested). Maximum nisin yield of 1.78 g/L of soy whey was obtained at 30°C and pH of 4.5 as opposed to 2.96 g/L of nisin with MRS medium

Dynamics of Hot QCD Matter -- Current Status and Developments

The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe, just after the Big Bang. In the meantime, advancements in theoretical works and computing capability extend our wisdom about the hot-dense QCD matter and its dynamics through mathematical equations. The exchange of ideas between experimentalists and theoreticians is crucial for the progress of our knowledge. The motivation of this first conference named "HOT QCD Matter 2022" is to bring the community together to have a discourse on this topic. In this article, there are 36 sections discussing various topics in the field of relativistic heavy-ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This article begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an overview of experiment results.Comment: Compilation of the contributions (148 pages) as presented in the `Hot QCD Matter 2022 conference', held from May 12 to 14, 2022, jointly organized by IIT Goa & Goa University, Goa, Indi

Production and characterization of value-added biorenewable chemicals

Nisin is the only FDA-approved bacteriocin with a GRAS (Generally Regarded as Safe) status, used as a biopreservative/shelf-life extender in foods and many other products including pharmaceutical, veterinary and health care products. It is produced commercially by fermentation of a milk-based medium, using strains of Lactococcus lactis subsp. lactis. However, being a dairy-based product requires its labeling since milk is an allergen. Also, since its high production cost is mainly dominated by its medium costs, an emerging trend has been observed with a growing number of studies aimed at finding alternative, non-dairy and preferably non-allergen-based substrates. In order to cut costs, and to also be an environmentally friendly approach, several of these substrates have been sourced from agriculture or aquaculture-based waste streams. The review included in this dissertation highlights the advantages of value-addition to waste and the promising potentials of some of these low-value nutritive sources for the production of high-value nisin. An in-depth study of soy whey (SW) as a non-dairy, nisin fermentation feedstock was performed using Lactococcus lactis. Results indicated that SW was able to produce equivalent biomass and nisin yields (2.18g/L and 619mg/L), as compared to the commercial medium, de Man-Rogosa-Sharpe (MRS) broth (2.17g/L and 672mg/L, respectively), without the need for external nutrient supplementation. This indicated the nutritive qualities of this co-product stream in being able to support the growth of a fastidious bacterial culture. The success of SW as a bacterial growth medium motivated the second study which focused on growing the oleaginous algal strain Chlorella vulgaris under mixotrophic and heterotrophic culture conditions. Microalgae are cultivated in large scale for several commercially important products among which algal lipids have gained increasing interest due to their use as biodiesel feedstock as well as a source of essential fatty acids with neutraceutical value. Photoautotrophic algal cultivation suffers from low growth rates while heterotrophic/mixotrophic modes have high media costs. In order to boost algal lipid production with lower media costs, two co-product streams, SW and thin stillage (TS) were tested as growth substrates. TS is a high-organic strength co-product generated from the dry-grind corn-ethanol industry. Traditional use of TS involves an energy-intensive concentration process to form "syrup" which finally ends up as animal feed in Distillers' Dried Grains with Solubles (DDGS). The cost-effectiveness and success of the corn-ethanol industry is highly dependent on the value of its co-products. Therefore, in order to be an economically viable and an environmentally sustainable process, researching new avenues for value-addition to TS is very important. As per the results from the current study, biomass yields (dry basis, db) from TS, SW and a synthetic control medium-MBM (modified basal medium) after 4 days of incubation were 9.8, 6.3 and 8.0 g/L with oil contents at 43, 11, and 27 % (w/w) respectively. Polyunsaturated fatty acids (PUFAs) or essential FAs, were found to be highest in Chlorella-TSoil (56%), followed by 38% in Chlorella-SWoil and 31% in Chlorella-MBMoil. Therefore, mixotrophic cultivation of C. vulgaris in TS and SW produced high yields of both algal biomass and lipids at low cost, thus adding value to co-product streams and improving economic viability of algal cultivation. The high algal oil yields from TS motivated the third study involving the use of oleaginous fungal strain, Mucor circinelloides for its potential in adsorbing/assimilating the oil and nutrients present in TS, for the production of lipid and protein-rich fungal biomass. Fungal batch cultivation for 2 days using a 6-L airlift reactor led to a 92% increase in oil yield from TS, relative to the original oil content, with concomitant reduction in suspended solids and chemical oxygen demand (COD) in TS by 95% and 89% respectively. M. circinelloides, when grown on TS gave a biomass yield of 20 g/L (dry basis), with a lipid content of 46 % (dwb). The polyunsaturated fatty acids were 52% of the total lipids. Overall, fungal cultivation on TS produced a high-protein animal feed and high-value fungal oil, thus improving corn-ethanol process economics. The fourth study focused on employing the "hurdle concept" and developing more efficient antimicrobial systems by combining plant essential oils (EOs) with food-grade organic acids. The seven most active oils among the sixteen tested, were combined with five different organic acids and the antimicrobial interactions (synergistic/additive/antagonistic) were examined against food-related pathogens. Malic and citric acid were the most inhibitory acids which showed synergism with mountain savory, redistilled oregano (RO), and cinnamon oils against S.aureus 25923 and with cassia, RO, and cinnamon oils against E.coli 25922. The only synergistic EO-acid combination against C.albicans 10231 was lemon myrtle-citric acid.</p

Data from: Growth profiling, kinetics and substrate utilization of low-cost dairy waste for production of β-cryptoxanthin by Kocuria marina DAGII

Dairy industry produces enormous amount of cheese whey compromising of major milk nutrients but remains unutilized all over the globe. The present study investigates the production of β-Cryptoxanthin (β-CRX) by Kocuria marina DAGII using cheese whey as substrate. Response surface methodology (RSM) and artificial neural network (ANN) was implemented to obtain the maximum β-CRX yield. Significant factors viz. yeast extract, peptone, cheese whey and initial pH were the input variables in both the optimizing studies and β-CRX yield and biomass were taken as output variables. The ANN topology of 4-9-2 was found to be optimum when trained with feed-forward back propagation algorithm. Experimental values of β-CRX yield (17.14 mg/L) and biomass (5.35 g/L) were compared and ANN predicted (16.99 mg/L and 5.33 g/L respectively) values were found to be more accurate compared to RSM predicted values (16.95 mg/L and 5.23 g/L respectively). Detailed kinetic analysis of cellular growth, substrate consumption and product formation revealed that growth inhibition took place at substrate concentrations higher than 12%(v/v) of cheese whey. Han and Levenspiel model was the best fitted substrate inhibition model that described the cell growth in cheese whey with a R2 and MSE of 0.9982 and 0.00477%, respectively. The potential importance of this study lies in the development, optimization, modelling and characterization of a suitable cheese whey supplemented medium for increased β-CRX production

Improved power loading scheme for orthogonal frequency division multiplexing based cognitive radio

A subcarrier power allocation scheme for orthogonal frequency division multiplexing (OFDM) based cognitive users has been proposed for spectrum sharing with primary users (PU) allowing secondary users (SU) to coexist in same as well as adjacent frequency bands by underlay and interweave approaches respectively. The SU sum capacity of reliable communication has been maximised under the constraints of total power, each sub‐channel power and PU aggregate interference limits. Based on the quality of channel gains and spectral distance from PU bands, the powers of subcarriers adjacent to PU bands are suitably controlled till the interference constraint of PUs are satisfied. Controlled subcarrier deactivation achieved by augmenting this ‘n‐adjacent’ power redistribution step to traditional OFDM water‐filling gives a powerful tool for efficiently maintaining high SU sum capacity without exceeding PU interference tolerance limit for a wide range of total power budget. Different water levels get assigned for the adjacent and non‐adjacent subcarrier groups. In terms of SU capacity and PU interference, the proposed algorithm outperforms some of the existing schemes having almost same complexity as the proposed one. The improvement is significant when the adjacent subcarriers channel gains are relatively ‘good’ or ‘bad’ compared with the non‐adjacent ones

GA based optimal power allocation for underlay cognitive radio networks

In this paper we have considered optimal power allocation for a system model of multiple secondary user (SU) pairs coexisting with a single primary user (PU) pair in a spectrum underlay cognitive radio network. A new Genetic algorithm (GA) based power allocation scheme has been proposed to achieve maximum system utility subject to PU interference constraint and satisfaction of QoS requirement of all the SUs. The GA method is capable of power allocation with much less computational time. The scheme is further tested with a modified system utility function that uses reduced number of constraints, by minimizing the aggregate primary interference power. This approach, besides being faster, has the advantage of significantly reducing the interference power, thereby allowing more number of secondary users. The performance comparisons of the two utility functions have been reported with respect to relevant system parameters. The accuracy and convergence performance of our proposed strategy matches very closely to that of geometric programming