Renewable fatty acid ester production in Clostridium

Bioproduction of renewable chemicals is considered as an urgent solution for fossil energy crisis. However, despite tremendous efforts, it is still challenging to generate microbial strains that can produce target biochemical to high levels. Here, we report an example of biosynthesis of high-value and easy-recoverable derivatives built upon natural microbial pathways, leading to improvement in bioproduction efficiency. By leveraging pathways in solventogenic clostridia for co-producing acyl-CoAs, acids and alcohols as precursors, through rational screening for host strains and enzymes, systematic metabolic engineering-including elimination of putative prophages, we develop strains that can produce 20.3 g/L butyl acetate and 1.6 g/L butyl butyrate. Techno-economic analysis results suggest the economic competitiveness of our developed bioprocess. Our principles of selecting the most appropriate host for specific bioproduction and engineering microbial chassis to produce high-value and easy-separable end products may be applicable to other bioprocesses.

Microbial production of butyl butyrate: from single strain to cognate consortium

Butyl butyrate (BB) is an important chemical with versatile applications in beverage, food and cosmetics industries. Since chemical synthesis of BB may cause adverse impacts on the environment, biotechnology is an emerging alternative approach for microbial esters biosynthesis. BB can be synthesized by using a single Clostridium strain natively producing butanol or butyrate, with exogenously supplemented butyrate or butanol, in the presence of lipase. Recently, E. coli strains have been engineered to produce BB, but the titer and yield remained very low. This review highlighted a new trend of developing cognate microbial consortium for BB production and associated challenges, and end up with new prospects for further improvement for microbial BB biosynthesis.

Experimental investigation on spray characteristics of Jet A-1 and alternative aviation fuels

Potential alternative fuels that can mitigate environmental pollution from gas turbine engines (due to steep growth in the aviation sector globally) are getting significant attention. Spray behavior plays a significant role in influencing the combustion performance of such alternative fuels. In the present study, spray characteristics of Kerosene-based fuel (Jet A-1) and alternative aviation fuels such as butyl butyrate, butanol, and their blends with Jet A-1 are investigated using an air-blast atomizer under different atomizing air-to-fuel ratios. Phase Doppler Interferometry has been employed to obtain the droplet size and velocity distribution of various fuels. A high-speed shadowgraphy technique has also been adopted to make a comparison of ligament breakup characteristics and droplet formation of these alternative biofuels with that of Jet A-1. An effort is made to understand how the variation in fuel properties (mainly viscosity) influences atomization. Due to the higher viscosity of butanol, the SMD is higher, and the droplet formation seems to be delayed compared to Jet A-1. In contrast, the lower viscosity of butyl butyrate promotes faster droplet formation. The effects of the blending of these biofuels with Jet A-1 on atomization characteristics are also compared with that of Jet A-1.

One-pot production of butyl butyrate from glucose using a cognate “diamond-shaped” E. coli consortium

Esters are widely used in plastics, textile fibers, and general petrochemicals. Usually, esters are produced via chemical synthesis or enzymatic processes from the corresponding alcohols and acids. However, the fermentative production of esters from alcohols and/or acids has recently also become feasible. Here we report a cognate microbial consortium capable of producing butyl butyrate. This microbial consortium consists of two engineered butyrate- and butanol-producing E. coli strains with nearly identical genetic background. The pathways for the synthesis of butyrate and butanol from butyryl-CoA in the respective E. coli strains, together with a lipase-catalyzed esterification reaction, created a “diamond-shaped” consortium. The concentration of butyrate and butanol in the fermentation vessel could be altered by adjusting the inoculation ratios of each E. coli strain in the consortium. After optimization, the consortium produced 7.2 g/L butyl butyrate with a yield of 0.12 g/g glucose without the exogenous addition of butanol or butyrate. To our best knowledge, this is the highest titer and yield of butyl butyrate produced by E. coli reported to date. This study thus provides a new way for the biotechnological production of esters.

One-pot production of butyl butyrate from glucose using a cognate “diamond-shaped” E. coli consortium

Esters are widely used in plastics, textile fibers, and general petrochemicals. Usually, esters are produced via chemical synthesis or enzymatic processes from the corresponding alcohols and acids. However, the fermentative production of esters from alcohols and/or acids has recently also become feasible. Here we report a cognate microbial consortium capable of producing butyl butyrate. This microbial consortium consists of two engineered butyrate- and butanol-producing E. coli strains with nearly identical genetic background. The pathways for the synthesis of butyrate and butanol from butyryl-CoA in the respective E. coli strains, together with a lipase-catalyzed esterification reaction, created a “diamond-shaped” consortium. The concentration of butyrate and butanol in the fermentation vessel could be altered by adjusting the inoculation ratios of each E. coli strain in the consortium. After optimization, the consortium produced 7.2 g/L butyl butyrate with a yield of 0.12 g/g glucose without the exogenous addition of butanol or butyrate. To our best knowledge, this is the highest titer and yield of butyl butyrate produced by E. coli reported to date. This study thus provides a new way for the biotechnological production of esters.

THE RAMIFICATION PATTERN OF PORTAL VEIN IN LEFT LOBE OF HUMAN LIVER STUDIED BY CORROSION CAST METHOD.

INTRODUCTION: The aim of the study was to know the intrahepatic ramication pattern of portal vein in left lobe of liver & its variations. METHODS: 25 human fresh livers were obtained after autopsy and studied by corrosion cast method. Polymeric granules of butyl butyrate were dissolved in acetone and 20% homogenous solution was made. Solution was injected into portal vein and the injected liver was placed in 10 % formal saline for 24 hours at room temperature (20°C) for polymerization of infused butyl butyrate solution. Maceration of liver tissue achieved by whole-organ immersion in 1.8 N KOH solution at 68°C for 24 hrs. Each cast thus obtained was preserved in glycerin and details were studied. RESULTS: The length of the transverse part of Left portal vein (LPV) varies from 1.5 -3.7 cm (2.6 cm) while the length of umbilical part of LPV varied from 0.5 – 1.5 cm. (1.1cm.) and total length of LPV varies from 2.0 cm.-4.8cm.(3.7cm). Ramication of Left Portal Vein was described on the basis of its umbilical part. Two type of pattern observed Type I (Umbilical Part Turned Inferiorly) 60 % cases & Type II (Umbilical Part Turned Superiorly). For segment II - Cranio- lateral (CAL) branch originated from the convexity of the curved portion of the umbilical part 84 % cases while in 16 % it has originated from the transverse part of the LPV. Segment III- Caudo- lateral branch (CRL) originated from the convexity of the curved portion of the umbilical part of LPV in all the cases. Segment IV- From the concavity, Inferio – medial branch ran downward & medially while superior- medial branch ran superiorly & medially to supply the lower & upper part of segment IV respectively. The both superio- medial & inferio-medial branches were present in 13 of 25 cases (52 %), while only superior -medial branches were present in 16 of 25 cases (64 %) cases & only inferio-medial 21 of 25 cases (84%) in cases. In 5 of 25 cases (20 %), a common trunk has originated from the concavity of curved portion of the umbilical part then it divided in to superior-medial & inferio-medial branches to supply the segment IV. The number of portal branches to the caudate lobe (segment I) varied from 1 to 4 branches: most commonly from LPV (52 %), then portal vein (16%) & then right portal vein12% cases. At least one of these branches was always originated from LPV (100%). The number of the branches to supply the caudate lode was 2 as it observed in 56 %, while 3 braches in 16 % cases & 4 branches were present in only 8% of the cases. The ndings of present CONCLUSIONS: study on hepatic vasculature have immense importance in the eld of hepato-biliary surgeries.