Bioproducts Research Articles

Comparative Evaluation of the Methods of Palm Sap Fermentation for Bio-ethanol Production

This paper evaluates the methods of fermenting palm sap for bio ethanol production and compares the yield. A survey was carried out in three local government in Akwa Ibom State, Nigeria; Essien Udim, Ikot Abasi and Uruan local government area. Personal interviews were conducted with local palm wine dealers and questionnaires distributed. Three types of palm trees were found dominant in these areas; oil, raphia and nypa palm tree. The sap from these three palm trees were used in investigation. Two methods were investigated; natural and yeasted fermentation using saccharomyces cerevisae. 60% respondents of the questionnaires agreed on using additives to speed up fermentation. Experiments were carried out in which the result shows that yeasted fermentation yields more alcohol than natural fermentation and also reduce the period of fermentation.

Production and Characterization of Biopolyols from Crude Glycerol Based Liquefaction Process

The feasibility of using palm kernel cake and crude glycerol in liquefaction process to produce bio polyol was investigated in this study. The identiied parameters for liquefaction conditions were reaction temperature, reaction time, biomass loading and acid loading. The optimal liquefaction conditions for bio polyol production were determined to be 10%(w/w) biomass loading, 1%(w/w) acid loading, and reaction temperature at 160°C for 90min. The optimal condition yielded 83 % biomass conversion with hydroxyl and acid numbers of 552 mg KOH/g and 0.56 mg KOH/g respectively. Result shows that palm kernel cake and crude glycerol can be used as an alternative raw material and liquefaction solvent to the production of bio polyol.

The Advantages of Soaking with Aqueous Ammonia Pre-treatment Process of Oil Palm Empty Fruit Bunches

Oil palm empty fruit bunches (OPEFB) as one of lignocellulosic biomass, consists of three main components: cellulose, lignin, and hemicelluloses. Cellulose may occur in a crystalline form in addition to amorphous form. Cellulose and hemicelluloses can be converted into fermentable sugar, i.e. glucose and xylose, by chemical or enzymatic hydrolysis. These sugar usually used as a feedstock of bio ethanol production. Lignin and high-crystallinity of cellulose are inhibits the performance of enzymatic hydrolysis process. Therefore pretreatment is necessary to remove lignin, decrease the crystallinity and improve the yield of enzymatic hydrolysis. One of the developed pre-treatment processes is soaking with aqueous ammonia solution or called by SAA process. In this study, the advantage of SAA pre-treatment process was investigated using ammonium solution prior to the enzymatic hydrolysis. The pre-treatments were carried out in various ammonium concentrations (5%, 7.5%, and 10%) at mild conditions (25 o C and 1 atm) for 24 hrs, and with or without a following additional diluted-acid pre-treatment (92 – 98 o C and 1 atm for 1 hour). The pre-treated materials were then enzymatic hydrolyzed by cellulose and β-glycosidase for 96 hrs and anaerobic digested by inoculums microbial. The changes in cellulose crystallinity were analyzed by FTIR Spectroscopy. The OPEFB pre-treated by 10% ammonium solution without a following dilute-acid pre-treatment shows low crystallinity with a crystallinity index (CI) of 0.80 compared to that of the untreated material (2.11). The method could increase the yield of hydrolyzed glucose to 79% compared with that of untreated material (13 g/g glucan added). The results also show increasing the methane production from 0.18 Nm 3 /g volatile solid to 0.35 Nm 3 /g volatile solid via anaerobic digestion.

Quality-by-Design (QbD) process evaluation for phytopharmaceuticals on the example of 10-deacetylbaccatin III from yew

The focus of pharmaceutical product development lies on assuring excellent product quality at the end of a cost-efficient process. The Quality-by-Design (QbD) concept shifts the focus from quality assurance through testing to quality control by process understanding, resulting in very robust processes with high quality product. QbD was originally intended by authorities for biologics, where product quality proven completely by analytics is not desired. Product quality has to be controlled by means of appropriate processes and operations as well. These demands were developed in order to improve patients’ safety by optimal drug quality at more efficient manufacturing processes reducing costs for healthcare systems. Furthermore, production of bio- logics includes feedstock variability and complex multi-step manufacturing processes in batch operation with variable lots –condition, which apply to botanicals as well. The use of rigorous (physico-chemical) process modeling in combination with QbD results in a high degree of process understanding. This offers, contrary to popular prejudices, great benefit for manufac- turers with little extra effort during development. The methodical QbD-based approach is pursued to develop a process for extraction and purification of 10-deacetylbaccatin III from yew needles. A short history and key elements of the QbD-based application are introduced. The line of argument for basic process conception is described and initial risk assessment is shown. Typical raw material variation and vaporization are identified as causes of process variability, therefore, the implications to subsequent process steps are pointed out. Finally, influences of load and flow rate on the chromatographic separation of 10-deacetylbaccatin III are shown to exemplify sensitivity of purifica- tion design.

Kinetic Study on Catalytic Conversion of Glycerol to Renewable Acrolein

Biodiesel is a suitable alternative to gasoline and diesel since it emits less carbon emission. There has been a surplus of glycerol in the market due to biodiesel production. Glycerol may be a good source of bio-based feed since it is from a renewable source. The kinetic study of gas-phase glycerol dehydration reaction using a supported ?-Al2O3 nanoparticle based solid heteropoly acid catalyst (SiW20-Al/Zr10) has been investigated. A kinetic model was established, based on the reaction mechanism, taking into account two parallel reactions of glycerol degradation into acrolein or acetol. All the reaction rate constants and activation energies were determined at various reaction temperatures (280 – 340 °C). The first-order kinetic model and the experimental data fitted-well. Results revealed that all the rate constants increased with temperature, and the activation energies of glycerol dehydration to acrolein and acetol were 46.0 and 53.3 kJ/mol. The results from this study are useful for simulation and process modelling of a bio-refinery for sustainable production of bio- based chemicals.

Production of ethanol and bio-chars from Pakistani ligno-cellulosic biomasses

ABSTRACTThe objective of this study was the production of ethanol from two locally available lingo-cellulosic biomasses: rice hulls and wheat straw. Both biomasses were ground to a particle size of 2 mm and pretreated with 2.5% solution of NaOH and the dried masses were individually subjected to enzymatic hydrolysis using cellulase enzyme in buffer solutions. Fermentation of the hydrolyzed products was carried out by using saccharomyces cervices under anaerobic conditions at 35°C for three days of incubation period. The rice hulls and wheat straw produced 15.22 mg/ml and 25.02 mg/ml ethanol, respectively, (on the last day) with appreciable yields. The two bio fermentation residues were used for the production of bio using fixed-bed pyrolysis. At the optimum temperature of chars 600°C, the bio-char products from rice hulls contained 56.15% fixed carbon and 40.88% volatile matter (VM) with a gross calorific value of 7513 Kcal/Kg, whereas bio-chars from wheat straws contained 53.69% fixed carbon, 45.19% VM, and a gross calorific value of 7123 Kcal/Kg. Both bio-chars appear to be good value added products for fuel applications, activated carbon production, and carbon dioxide sequestration.

Production of Biopesticides Namely Trichoderma viride and Beauveria bassian

Objectives: To highlight the barriers to the effective usage of biopesticides and solutions to these barriers for biopesticides produced from fungi Trichoderma viride and Beauveria bassiana . Methods and Statistical Analysis: Recent paper in last decade on production techniques and method of biopesticides from environmental friendly fungi namely T. viride and B. bassiana have been reviewed and analyzed. Findings: Optimized conditions of temperature and pressure can maintain the pH at about 7 which will result in an enhancement in the shelf life of the biopesticides from 2-3 months to about 1 or 1.5 years. Effective selection of carrier can benefit in the stability of the biopesticides characteristics and also decrease the cost of the products. The usage of metabolites and additives can highly affect the performance of the bio products and can increase their potential. Application/Improvements: Active packaging could greatly enhance/increase the shelf life of the biopesticides and thereby making them viable alternative cheap ecofriendly biopesticides for organic farming.

Pretreatment optimization of the biomass of Microcystis aeruginosa for efficient bioethanol production

Microalgae are considered to be the future promising sources of biofuels and bio products. The algal carbohydrates can be fermented to bioethanol after pretreatment process. Efficient pretreatment of the biomass is one of the major requirements for commercialization of the algal based biofuels. In present study the microalga, M. aeruginsa was used for pretreatment optimization and bioethanol production. Treatment of algal biomass with CaO before acid and/or enzymatic hydrolysis enhanced the degradation of algal cells. Monomeric sugars yield was increased more than twice when biomass was pretreated with CaO. Similarly, an increase was noted in the amount of fermentable sugars when biomass was subjected to invertase saccharification after acid or lysozyme pretreatment. Highest yield of fermentable sugars (16 mM/ml) in the centrifuged algal juice was obtained. 4 Different microorganisms’ species were used individually and in combination for converting centrifuged algal juice to bioethanol. Comparatively higher yield of bioethanol (60 mM/ml) was obtained when the fermenter microorganisms were used in combination. The results demonstrated that M. arginase biomass can be efficiently pretreated to get higher yield of fermentable sugars for enhanced yield of bioethanol production.

채소 부산물과 표고 수확후 배지를 활용한 퇴비 제조방법

Spent mushroom substrate (SMS) has generally been used for the manufacture of animal feed and production of bio fuel. Limited research has been conducted in the utilization of SMS as a co-material for composting. Therefore, the main purpose of this study was to evaluate the feasibility of composting vegetable waste mixed with various ratios of SMS (30, 40, and 50%). The results showed that the C/N ratio decreased when both sawdust (from 22.0~28.8 to 17.7~20.4) and SMS (from 18.5~19.5 to 12.7~16.8) were applied for composing, owing to increased contents of nitrogen. A maturity test conducted using mechanical (Solvita) and germination tests revealed that both sawdust (92.0~101.9%) and SMS (87.8~89.2%) satisfied a criteria of maturity standard (70%). A correlation analysis between compost maturity and its chemical properties revealed that the C/N ratio and pH were the most dominant parameters for compost maturity. Overall, SMS could be utilized as a compost material and especially, vegetable waste mixed with SMS could provide sufficient nutrients for crop growth.

Plasma-derived human factor X concentrate for on-demand and perioperative treatment in factor X-deficient patients: pharmacology, pharmacokinetics, efficacy, and safety

ABSTRACTIntroduction: Hereditary factor X (FX) deficiency is a rare autosomal recessive bleeding disorder characterized mainly by mild-to-severe bleeding into the mucous membranes, muscles or joints. Previously, treatment options for hereditary FX deficiency were limited mostly to products that may not specify FX content (i.e. fresh frozen plasma and prothrombin complex concentrates) and that have associated safety concerns. To meet the need for a single-factor replacement therapy specifically for use in FX-deficient patients, a high-purity, high-potency, human plasma-derived FX concentrate (pdFX; Coagadex®; Bio Products Laboratory, Elstree, UK) has been developed and approved for treatment of perioperative bleeding and on-demand treatment in FX-deficient patients.Areas covered: The pharmacology, efficacy, and safety of pdFX are discussed, with a review of preclinical studies and clinical trial data that led to regulatory approval of pdFX in the United States and Europe.Expert opinion: As the first single-factor replacement therapy indicated for hereditary FX deficiency, pdFX is a safe and efficacious treatment option in patients aged ≥12 years with hereditary FX deficiency. Clinical studies of pdFX provide a dosing regimen for use in cases of bleeding episodes, surgery, and prophylaxis. Further studies are ongoing regarding use of pdFX long term and in patients aged ≤12 years.

بررسی توانایی چند گیاه دارویی در کنترل قارچ های عامل پوسیدگی انباری Rhizopus nigricans) و Alternaria alternate) در گوجه فرنگی های تولید شده در سامانه های کشاورزی رایج و زیستی

بیماری پوسیدگی ریزوپوسی و نقطه سیاه از مهم ترین بیماری های انباری در گوجه فرنگی می باشند. به منظور بررسی توانایی چند گیاه دارویی بر ماندگاری و کنترل قارچ های عامل پوسیدگی انباری Rhizopus nigricans) و Alternaria alternate) در گوجه فرنگی های تولید شده در سامانه های کشاورزی رایج و زیستی، آزمایشی به صورت فاکتوریل در قالب طرح کاملا تصادفی با 14 تیمار و سه تکرار در دانشگاه فردوسی مشهد در سال 1389 اجرا شد. دو سامانه تولید شامل گوجه فرنگی رایج و زیستی (ارگانیک) و شش گونه گیاهی (آویشن (Thymus vulgaris L.)، پونه (Mentha pulegium L.)، نعناع فلفلی (Mentha piperita L.)، اکالیپتوس (Eucalyptus globules L.)، کرچک (Ricinus communis L.) و گوجه فرنگی (Lycopersicom esculentum Mill.)) به همراه تیمار شاهد به ترتیب عامل اول و دوم در این آزمایش بودند. بر اساس نتایج آزمون غیر پارامتری کروسکال– والیس، تفاوت معنی داری بین سامانه های تولید گوجه فرنگی های ارگانیک با نوع غیرارگانیک آن از نظر سرعت پوسیدگی انباری ناشی از رشد قارچ های بیماری زا مشاهده شد. به طوری که در گوجه فرنگی های ارگانیک، سرعت پوسیدگی (47/1 عدد میوه در هفته) تا حدود 20 درصد کمتر از نوع غیرارگانیک آن بود. نتایج حاصل از آنالیز غیرپارامتری گونه های گیاهی نیز حاکی از وجود تفاوت بین این گونه ها از نظر تأثیر بر سرعت پوسیدگی انباری در گوجه فرنگی بود؛ به طوری که به جز کرچک و گوجه فرنگی، سایر گیاهان دارویی منجر به کاهش معنی دار سرعت رشد و توسعه قارچ های بیماری زا در انبار شدند.

CONTAMINATION WITH HEAVY METALS AND PAH's IN SOIL IN THE CANTON SARAJEVO IN PERIOD 2009-2015

UDK 631.453(497.6)
 In accordance with the role and importance of which in the world and in our country is attached to soil as a bio production factor, the need to examine and protect soil from contamination is imposed. Heavy metals are very common contaminants of soils. Highly toxic and carcinogenic PAHs are natural components of raw petro chemical compounds. Due to their negative influence on plants and animal world as well as on human population, it is necessary to evaluate and determine heavy metals and PAHs content in soils, especially in ones intended for agricultural production.
 In this work, we have examined agricultural and urban soils in the Canton Sarajevo, for content of heavy metals and polycyclic aromatic hydrocarbons. Analyzed samples were in scattered state, taken from a depth of 0-30 cm. The total number of determined soil samples was one hundred and twenty (120), in the period of 2009-2015.
 According to determined general chemical characteristics, soils are from slightly acetous to slightly alkaline. According to mechanical texture composition, examined soils have showed the following texture marks by Ehwald: clay and sandy loam.
 Using flame/electrothermal atomic absorption spectrometry and gas chromatography with FID detection we have established the content of seven heavy metals and polycyclic aromatic hydrocarbons. In determining the content of heavy metals following methods were used: BAS ISO 11466:2000 and BAS ISO 11047:2000, and for PAHs the method was BAS ISO 18287:2008. Results were compared with the limit values from "Regulation on determining the allowable amounts of harmful and dangerous substances in soils and methods of their examination" specified in Official Gazette of the Federation of B&H, No. 72/09.

Semi Intensive and Semi Biofloc Methods for the Culture of Indian White Prawn, Fenneropenaeus indicus in High-density Polyethylene Liner Ponds

An experiment (triplicated) was conducted to assess the growth and production of Indian white prawn, Fenneropenaeus indicus in semi intensive and semi biofloc culture technique for a period of 120 days in polythene liner ponds (300 m2). Water exchange was done at 10% in semi intensive culture method (control) and zero water exchange was done in semi biofloc method (treatment). Soya hull and molasses were added as carbon sources to induce biofloc formation in treatment ponds. Post larvae (PL20) were stocked at the rate of 100/m2 in each pond and fed with a standard shrimp feed. Shrimp growth, physico-chemical parameters of water, bacteria, phytoplankton and zooplankton population, immune response and physical quality of shrimp were recorded during the period. Significant difference (p < 0.01) in shrimp growth (weight) was observed between control and treatment. Phytoplankton population and total haemocyte count were found to be increased and pathogenic bacteria population decreased in treatment ponds. Strong linear relationship was found between growth and biofloc content in treatment ponds. Shrimp grown in biofloc pond showed better colour and taste compared to control. Semi biofloc technique can be considered as an ideal culture method for bio secure production of white shrimp in semi arid lands.

Effect of biozyme (R) on soil and crop biometrics in rice-wheat system

Summary A registered product biozyme is extracted from a Norwegian Sea weed known as Ascophyllum nodosum. It is biodegradable and non-toxic for the plant and soil health as claimed by Biostadt company. Beside biozyme, several other zymes are also available in the market with some prefixes in the name. They claim, the zyme is toxin free, eco-friendly, bio degradable product containing growth hormones, elements, minerals and vitamins. Highly compatible with fertilizers and pesticides, it also increases the resistance of plants against various pests, diseases and climatic stress. These zymes are available in solid and liquid form and are being used as either top dressing or spraying on the crop canopy at important crop growth stages. As per some earlier studies, biozyme have claimed to have beneficial in crop growth both in vegetative part as well as in grain production. Keeping in view of its importance a field trial was formulated and being conducted in research farm of Bihar Agricultural University Bhagalpur (Bihar) to see the impact of Biozyme on the yield and soil microbes.

Cloning and expression of Saccharomyces cerevisiae SUC2 gene in yeast platform and characterization of recombinant enzyme biochemical properties.

Invertase (EC.3.2.1.26) catalyzes the hydrolysis of sucrose to an equimolar mixture of d-glucose and d-fructose which is of interest for various industrial applications. In this research, Saccharomyces cerevisiae invertase gene (SUC2) was optimized based on Pichia pastoris codon preference. The synthetic gene was introduced into the methylotrophic yeast Pichia pastoris under the control of the inducible AOX1 promoter. High level of the extracellular recombinant invertase (R-inv) production was achieved via methanol induction for 4 days and purified by His-Tag affinity chromatography which appeared to be a mixture of glycosylated proteins with various sizes of 85–95 kDa on SDS-PAGE. Deglycosylation of the proteins by Endo-H resulted in the proteins with average molecular weight of 60 kDa. The purified recombinant invertase biochemical properties and kinetic parameters determined a pH and temperature optimum at 4.8 and 60 °C, respectively, which in comparison with native S. cerevisiae invertase, thermal stability of recombinant invertase is highly increased in different heating treatment experiments. The purification of recombinant invertase resulted in an enzyme with specific activity of 178.56 U/mg with 3.83-fold of purification and the kinetic constants for enzyme were Km value of 19 mM and Vmax value of 300 μmol min−1 mg−1 With kinetic efficiency (Kcat/Km) of 13.15 s−1 mmol−1 it can be concluded that recombinant P. pastoris invertase can be more effective for industrial quality criteria. We conclude that recombinant P. pastoris enzyme with broad pH stability, substrate specificity and proper thermal stability can fulfil a series of predefined industrial quality criteria to be used in food, pharmaceutical and bio ethanol production industries.

Optimization of Acid Treatment of Cashew Peduncle for Ethanol and Xylitol Production

Due to the large amount of waste generated by industries and commitments for environment preservation, there has been a growing interest in the use of alternative energy sources for the production of bioproducts of added value such as ethanol and xylitol. In this context, cashew has been considered a promising alternative to meet the global demand in a more sustainable way. Thus, the aim of this study was to optimize the acid treatment of cashew peduncle for biotechnological production of ethanol and xylitol. Physicochemical analyseswere held for bagasse characterization, and sugars were assessed by HPLC (glucose, xylose and arabinose) and fermentation inhibitors (acetic acid, furfural and hydroxymethylfurfural) in the hydrolyzed liquor. The 23+3 factorial experimental design was applied with a total of 11 experiments to investigate the influence ofvariables temperature, bagasse/acid diluted and acid concentration to evaluate the release of pentoses (xylose and arabinose) and hexose (glucose) in the hydrolyzed liquor. The liquor from the acid treatment should operate under ratio conditions temperature at level +1 (160 °C), acid concentration and bagasse:diluted acid at level -1 (1% and 1:6), obtaining pentose yields (xylose and arabinose). It was observed that acid treatment liquor is very effective in providing high-susceptibility substrates for ethanol and xylitol production.

Production and turnover of ectomycorrhizal extramatrical mycelial biomass and necromass under elevated CO2 and nitrogen fertilization.

Extramatrical mycelia (EMM) of ectomycorrhizal fungi are important in carbon (C) and nitrogen (N) cycling in forests, but poor knowledge about EMM biomass and necromass turnovers makes the quantification of their role problematic. We studied the impacts of elevated CO2 and N fertilization on EMM production and turnover in a Pinus taeda forest. EMM C was determined by the analysis of ergosterol (biomass), chitin (total bio- and necromass) and total organic C (TOC) of sand-filled mycelium in-growth bags. The production and turnover of EMM bio- and necromass and total C were estimated by modelling. N fertilization reduced the standing EMM biomass C to 57% and its production to 51% of the control (from 238 to 122kgCha(-1) yr(-1) ), whereas elevated CO2 had no detectable effects. Biomass turnover was high (˜13yr(-1) ) and unchanged by the treatments. Necromass turnover was slow and was reduced from 1.5yr(-1) in the control to 0.65yr(-1) in the N-fertilized treatment. However, TOC data did not support an N effect on necromass turnover. An estimated EMM production ranging from 2.5 to 6% of net primary production stresses the importance of its inclusion in C models. A slow EMM necromass turnover indicates an importance in building up forest humus.

Nanomaterials with antioxidant properties, obtained via biotechnology, using the solid state biosynthesis

ABSTRACTTwo nano materials type emulsion (EP and EM), that includes two different bioactive metabolites of Monascus sp. were obtained. Prior obtaining the nanoemulsion, tha enatural extracts, P (Monascus sp.1 – parental strain) and M (Monascus sp.2 - modified strain), were conditioned in order to increase their stability and biodisponibility. The new nanomaterials obtained were tested in terms of physical and chemical characteristics, by dynamic light scattering, infrared spectra and thermal analysis. Biological properties was investigated, by determining the effects of these new bio materials on wound healing and by measuring the antioxidant properties. The results obtained reveal the presence of aggregates with dimensions in the range of 1–100 nm, proving that these bioproducts are nano materials. The infrared spectra indicate the presence of benzene metadisubstituted (bands at 881.25 cm−1 and 880.4 cm−1 respectively), which are specific to Monascus metabolites Thermal analysis indicate the similarities between the matrix used in conditioning and the final nano products contains Monascus metabolites. The influence of these nano bio products on cicatrisation process was determined by tests on mices. It was concluded that there is small positive effect of the extracellular EP product. In this case, the bio product increase with 3% the rate of cicatrisation process, in comparison with the witness. All the two nano products show a significant antioxidant properties, with specific quenching rate of 97.7%

Performance of biodiesel/higher alcohols blends in a diesel engine

Summary Alcohols extensively used in internal combustion engines are important renewable and sustainable energy resources from environmental and economical perspectives. Besides, bio production of alcohols decreases consumption of fossil-based fuels. Although there are many studies with regards to the use of lower alcohols such as methanol and ethanol in internal combustion engines, there are a limited number of investigations with higher alcohols. Higher alcohols such as propanol, n-butanol, and 1-pentanol are part of the next generation of biofuels, given they provide better fuel properties than lower alcohols. Biodiesel–higher alcohol blends can be used in diesel engines without any engine modification but need to be tested under various engine conditions with long periods in order to evaluate their impacts on engine performance and environmental pollutants. The objective of this study was to evaluate the effect of using propanol, n-butanol, and 1-pentanol in waste oil methyl ester (B100) on engine performance and exhaust emissions of a diesel engine running at different loads (0, 3, 6, and 9 kW) with a fixed engine speed (1800 rpm). Test fuel blends were prepared by adding propanol, n-butanol, and 1-pentanol (10 vol.%) into waste oil methyl ester to achieve blends of B90Pr10, B90nB10, and B90Pn10, respectively. According to engine performance and exhaust emissions results, the addition of propanol, n-butanol, and 1-pentanol to B100 had the effect of increasing brake specific fuel consumption and exhaust gas temperatures. The brake thermal efficiency (BTE) decreased for B90Pr10 and B90nB10, while B90Pn10 showed a slight increase in BTE as compared with B100. When compared with B100, B90Pr10, B90nB10, and B90Pn10 decreased carbon monoxide emissions at lower loads while it increased slightly at 9 kW load. The decrement in oxides of nitrogen emission was observed at whole loads for B90Pr10, B90nB10, and B90Pn10 compared with B100. When considering all loads, B90Pn10 presented the best mean hydrocarbon emission with a reduction of 45.41%. Copyright © 2016 John Wiley & Sons, Ltd.

Membrane engineering via trans unsaturated fatty acids production improves Escherichia coli robustness and production of biorenewables

Constructing microbial biocatalysts that produce biorenewables at economically viable yields and titers is often hampered by product toxicity. For production of short chain fatty acids, membrane damage is considered the primary mechanism of toxicity, particularly in regards to membrane integrity. Previous engineering efforts in Escherichia coli to increase membrane integrity, with the goal of increasing fatty acid tolerance and production, have had mixed results. Herein, a novel approach was used to reconstruct the E. coli membrane by enabling production of a novel membrane component. Specifically, trans unsaturated fatty acids (TUFA) were produced and incorporated into the membrane of E. coli MG1655 by expression of cis-trans isomerase (Cti) from Pseudomonas aeruginosa. While the engineered strain was found to have no increase in membrane integrity, a significant decrease in membrane fluidity was observed, meaning that membrane polarization and rigidity were increased by TUFA incorporation. As a result, tolerance to exogenously added octanoic acid and production of octanoic acid were both increased relative to the wild-type strain. This membrane engineering strategy to improve octanoic acid tolerance was found to require fine-tuning of TUFA abundance. Besides improving tolerance and production of carboxylic acids, TUFA production also enabled increased tolerance in E. coli to other bio-products, e.g. alcohols, organic acids, aromatic compounds, a variety of adverse industrial conditions, e.g. low pH, high temperature, and also elevated styrene production, another versatile bio-chemical product. TUFA permitted enhanced growth due to alleviation of bio–product toxicity, demonstrating the general effectiveness of this membrane engineering strategy towards improving strain robustness.