Current Biochemical Engineering (Discontinued) - Volume 7, Issue 1, 2021

Exploring low-cost, green, and safe technologies to provide an alternative to the conventionally selective catalytic reduction process is key to control the NOx emission from small-scale boilers and other industrial processes. For meeting this demand, the chemical absorption-biological reduction integrated system has been developed recently. This system applies Fe(II)EDTA for NO absorption and for the absorbent regeneration by iron-reducing and denitrifying bacteria . Many studies have focused on the enhancements of mass transfer and biological reaction, among which the biological processes were the rate-limiting steps. This review summarizes the current researches on the biological processes in the CABR system, which focuses on the mechanism and enhancement of biochemical reactions, and it also provides the possible directions for future research.

Algae (both micro and macro) have gained huge attention in the recent past for their high commercial value products. They are the source of various biomolecules of commercial applications ranging from nutraceuticals to fuels. Phycobiliproteins are one such high-value low volume compounds that are mainly obtained from micro and macroalgae. In order to tap the bioresource, a significant amount of work has been carried out for large scale production of algal biomass. However, work on downstream processing aspects of phycobiliproteins (PBPs) from algae is scarce, especially in the case of macroalgae. There are many difficulties in cell wall disruption of both micro and macro algae because of their cell wall structure and compositions. At the same time, there are several challenges in the purification of phycobiliproteins. The current review article focuses on the recent developments in downstream processing of phycobiliproteins (mainly phycocyanins and phycoerythrins) from micro and macroalgae. The current status, recent advancements and potential technologies (that are under development) are summarised in this review article besides providing future directions for the present research area.

Background: The influx of 3D printing in organ transplantation is currently a rigorous area of research, and its success is still cynical. This review article focuses mainly on the scope and challenges in the applications of 3D printing in organ transplantation. The basic idea of the article is to highlight the current status of 3D printing in the area of organ transplants. Introduction: The review article covers the highlights about the 3D printing, major steps incurred in the 3D printing of organs, challenges in the 3D printing and transplantation of organs, and future prospects (scope) in the area with special reference to the problem and failures encountered in organ transplantation of 3D printed organs. Methods: The findings from available studies have been consolidated in the review article to provide insight into the scope and challenges in the area of 3D printed organ transplantation. Results: In the review study, it has been found that there are certain limitations of the 3D printed material based on the survival and multiplication in the in-vivo environment, which subsequently leads to the bio incompatibility of the organs. In addition to this, some other limitations which provide further scope of research in this area are also included. Conclusion: It has been concluded that 3D printing is an emerging solution in organ transplantation and prosthetics, but still more refinement and technological advancement is needed to make it a completely feasible solution. Doctors, scientists, and engineers need to work in a cross-disciplinary manner to overcome the limitations and develop this technique further for the betterment of mankind.

Background: Hairy root culture has been widely used in the production of metabolites in dicotyledons, and a large number of food crops and medicinal plants in monocotyledons need to be developed. However, there are many difficulties in the induction of hairy roots in monocotyledons. The purpose of this paper is to introduce the inducing methods, influencing factors, and application of hairy roots in monocotyledons, and to promote the development of hairy root system in monocotyledons. Methods: The mechanism of action of Agrobacterium rhizogenes and the current situation of hairy root induction, induction methods and influencing factors of monocotyledons were summarized to provide convenience for efficient acquisition of hairy root of monocotyledons. Results: Monocotyledons are not easy to produce phenols. Cells are prone to lignification, adverse differentiation and selective response to Agrobacterium rhizogenes strains. It is proposed that before induction, plant varieties and explants should be selected, and different infection strains should be screened. In the process of hairy root induction, exogenous inducers such as acetosyringone can be added. Although these factors can provide some help for the induction of hairy roots in monocotyledons, we still need to pay attention to the disadvantages of monocotyledons from dicotyledons at the cellular level. Conclusion: A large number of food crops and medicinal plants are monocotyledons. Hairy root culture can be used to help the breeding and production of medicinal substances. Therefore, it is necessary to pay attention to the selection of varieties and explants, the selection of Agrobacterium rhizogenes and the addition of acetosyringone in the process of hairy root induction to improve the production efficiency and facilitate the development and utilization of monocotyledons.

Background: Global seafood production has doubled over the last two decades with aquaculture now contributing nearly 50% of supply. Pressure to reduce or eliminate water and waste discharge from aquaculture increases with each passing year. In response to this pressure, producers have adopted increasingly sophisticated technology, expanding fish and shellfish production from 2,000 kg/ha to over 40,000 kg/ha. While water discharge has been drastically reduced, waste solids production from intensive aquaculture continues to pose a management challenge. One potential solution is to co-culture filterfeeding aquatic organisms with higher-value aquaculture species as a technique to harvest and covert excess bacterial and algal biomass into useful co-products and biofuels. Methods: Over a period of twenty years, the author and co-workers have designed and operated catfish and marine shrimp production systems employing co-culture of tilapia (Oreochromis niloticus) and brine shrimp (Artemia) to remove, concentrate, and convert microbial solids into animal biomass and biofertilizer. Past system operations are reviewed, and additional methods and data are presented and discussed. In the case of tilapia, a technique entitled “tilapia enhanced sedimentation” is evaluated for use in converting algae into concentrated fertilizer and fish flesh. Alternatively, brine shrimp are used to harvest and convert microbial solids into a potential fish-meal replacement. Results: Tilapia co-culture was shown to be cost-effective in controlling aquaculture system algal species and density, selectively removing cyanobacteria from culture water promoting green algal dominance, reducing off-flavor in cultured fish species. Tilapia co-culture at biomass levels from 20-25% of targeted fish carrying capacity was required to reduce algal and bacterial levels, significantly reducing oxygen demand and aeration requirements, Tilapia enhanced sedimentation was demonstrated to be effective in removing suspended algal and bacterial solids, concentrating excreted biomass into rapidly settling fecal pellets. Brine shrimp culture has been demonstrated at densities of 2,000-4,000 animals/ liter, corresponding to 4 gm/liter of dry weight animal biomass concentration. Brine shrimp are capable of conversation efficiencies as high as 50% of microbial dry weigh to brine dry shrimp weight, as opposed to < 3% conversion with tilapia. However, successful Artemia culture necessitates unique culture system design and management, requiring two-stage, multiple-batch cultures of uniformly sized cohorts to yield maximum growth and conversion efficiency. Unique pH and ammonia toxicity response of brine shrimp necessitates management protocols very different from typical aquatic animal culture. Tilapia harvested algal sludge is limited to fertilizer application, yielding a value of $0.10/kg at 98% dry weight. On the other hand, brine shrimp biomass can be used as a potential fish-meal replacement at a value of $ 1.50/kg dry weight. Conclusion: Utilization of co-culture of filter-feeder organisms such as tilapia and brine shrimp to harvest, concentrate, and convert algal and bacterial solids into concentrated sludge or animal biomass offers potential to provide value-added products from integrated aquaculture operations as a more environmentally friendly practice.

Background: Preventing substantial environmental hazards caused by noxious gases and solutes from sanitary landfills necessitates adequate regulations that require knowledge of the underlying mechanisms involved and the effect of various strategies. Mathematical models have been used to understand the development of landfill gas based on sequential biological growth and certain simple chemical and physical processes. Methods: The single-stage and multi-stage Monod landfill degradation model is based on a coupled system of rate equations containing a nonlinear term related to Michaelis- Menten kinetics of the enzymatic reaction. In this communication, an approximate analytical solution of the nonlinear differential equations is solved using a new approach of the homotopy perturbation method. Results: Substrate and biomass concentrations for the single-stage Monod landfill degradation model as well as biomass, solid, aqueous, acetic, and gases for the multi-stage model are derived for all possible values of parameters. Theoretical evaluations of the kinetic parameters such as the constant of Michaelis- Menten, mass-specific growth rate, half-saturation, and the death rate are reported. Conclusion: The accuracy of the proposed analytical expressions is validated by direct comparison with numerical simulations generated by MATLAB. A sensitivity analysis is presented to report the effect of all parameters on the governing model and the time required to reach the steady-state. The obtained analytical results are expected to contribute to a better understanding of the model and the effect of parameters and hence a better designing of experiments.

Background: A giant amount of poultry waste represents one of the threats to the environment, or conversely, a significant source of peptides and other substances in demand. Rational use of huge quantities of poultry waste, especially after industrial chicken processing, is one of the pillars of biorefinery of animal wastes. Introduction: Six different animal wastes: chicken feathers, cartilages and the residue after meat separation, sheep wool, rabbit hair, and the rest of the goose feathers from blankets after cleaning were chosen for a hydrolysis test with malic acid as the initiator. Results: The newly designed hydrolysis of animal wastes at 140 oC with malic acid for initiation was successfully verified for all animal wastes. The resulting hydrolysates contained a mixture of amino acids, peptides, proteins, glycoproteins, and no salts. Conclusion: Hydrolysate applications for agriculture was successfully tested as a biostimulant in the form of a 10% water solution.

Background: Utilization of animal wastes in algal culture has proven to be challenging. The utilization of “free” nutrients has drawn researchers and industry to develop business models that call for the use of these free nutrients, which comes at a cost. Some of these costs include reduced productivity, increased contamination, lower value target markets, and lower treatment capabilities (for wastewater treatment applications). This paper evaluates the impact of dairy lagoon effluent on productivity and wastewater treatment ability. Methods: Screened dairy lagoon wash water was fed to four three square meter outdoor open paddlewheel algal cultivation reactors. The units were operated semi-continuously for one and a half years. Seasonal productivity and nutrient uptake rates, for nitrogen (N) and phosphorous (P) were measured against wastewater dilution requirements. Seasonal algal species dominance was also recorded. Wastewater was added at two levels, and the lower level was supplemented with synthetic fertilizer. Results: Seasonal N uptake rates ranged from 0.5 to 1.2 grams of N uptake per square meter per day, while P uptake ranged from 0.17 to 0.3 grams of P per square meter per day depending on season and Hydraulic Residence Time (HRT). N removal efficiency ranged at 40 to 70% for semicontinuous operation, depending on HRT, season, and dilution of influent wastewater, which was made up from 1.5% to 13% of the daily water exchange. Conclusion: Algal reactors tended to be N limited due to the inability to add enough dairy wastewater to mitigate the high turbidity and dark color. Treatments with lower levels of added dairy wastewater tended to show higher nutrient removal. Algal culture from dairy wash water could benefit from a pretreatment step to reduce turbidity and color, thereby promoting algal growth and productivity.

Background: Plastics are widely used in almost every manufacturing industry ranging from automobiles to medicine. Plastics take years to get degrade and have become a threat to the environment. Therefore there is a necessity to use biodegradable plastics in place of such nonbiodegradable plastics. Polyhydroxybutyrate or PHB is a type of biopolymer which has similar properties to that of synthetic plastics and is susceptible to degradation by microbes in the environment itself. PHB is produced in microorganisms such as bacteria or yeast under stress conditions. As the yeast has a large cell size, it can accumulate more PHB than bacteria and is also physiologically flexible, in addition to the advantage of using yeast rather than the bacterial cell for the production of PHB. Therefore, the aim of the study was to isolate PHB producing yeast strain from the agricultural field. Methods: Primary screening of isolates was performed using Sudan Black B for PHB production. The extraction of PHB was done using sodium hypochlorite digestion method. The quantification of extracted PHB was done by UV-VIS spectroscopy. Results: The percentage and amount of PHB extracted were found to be 13.4 % per biomass and 1.6mg/ml, respectively. Conclusion: A quite amount of PHB was able to be extracted from yeast isolate. As a future perspective, the enhancement of PHB production can be done using agricultural residues like sugarcane bagasse, corn cob, teff, banana peel, etc.