Microbial Biodiesel Research Articles

A comparative assessment of microbial biodiesel and its life cycle analysis.

Biodiesel is a type of sustainable, biodegradable energy made from natural sources like vegetable oils, animal fat, and from microbes. Unlike traditional diesel, it has a lower carbon footprint and produces fewer harmful emissions when burned. Biodiesel has gained popularity as a more sustainable substitute for hydrocarbon-based diesel and may be utilized in diesel engines without any modification. In this review, biodiesel from microorganisms such as algae, yeast, and fungi and advantages over another feedstock were discussed. The life cycle evaluation of biodiesel is a thorough assessment of the ecological and economic effects of biodiesel production and use, from the extraction of raw ingredients to the waste disposal process. The life cycle analysis considers the entire process, including the production of feedstocks, the production of biodiesel, and the use of biodiesel in vehicles and other applications. Life cycle analysis of biodiesel produced from microorganisms takes into consideration the environmental impact and sustainability of each step in the production process, including the impact on land use, water use, greenhouse gas emissions, and the availability of resources. In this section, biodiesel produced from microorganisms and other raw materials, its comparisons, and also steps involved in the life cycle such as the cultivation of microorganisms, harvesting of biomass, and conversion to biodiesel were discussed. The processes like extraction and purification, hydrothermal liquefaction, and their environmental impacts were examined by using various LCA software from the previously mentioned process.

The production of microbial biodiesel from cellulose-derived fungal lipid via consolidated bioprocessing

Lignocellulosic biomass from agro-industrial residues can potentially be used as carbon-rich carbohydrate feedstock for the conversion via oleaginous microorganisms into lipids, and subsequently microbial biodiesel. As multiple processes are required to conventionally convert lignocellulosic biomass into lipids, from the hydrolysis of carbohydrate into simple sugars for the fermentation, it is not economically favourable. Consolidated bioprocessing (CBP) combines the saccharification and fermentation of lignocellulosic biomass into a single processing step. As such, this study aims to screen multiple oleaginous fungi to identify the most effective lipid producers in CBP systems, followed by optimization study. Three different fungi (Aspergillus niger, Aspergillus oryzae, and Rhizopus sp.) were screened by the co-cultivation of monosaccharides. Rhizopus sp. yielded the highest lipid content. The response surface methodology (RSM) was used to optimize​ lipid production by Rhizopus sp. from cellulose in CBP systems. The CBP system with carbon concentration of 0.8% (w/v), temperature of 32 °C, and carbon to nitrogen ratio (C/N) of 99.5, yielded the optimum lipid content (51.8%). The lipid from Rhizopus sp. was then converted into biodiesel, that comprised 56.0% of saturated fatty acids. Fuel properties analysis indicated that microbial biodiesel from lipids of Rhizopus sp. is a promising alternative to diesel fuel.

Petroleum Sludge as a Feedstock for the Microbial Biodiesel Production: Emerging Prospects

Petroleum Sludge as a Feedstock for the Microbial Biodiesel Production: Emerging Prospects

Biodiesel Production from Bioremediation of Palm Oil Mill Effluent via Oleaginous Fungi

AbstractPalm oil mill effluent (POME) is a by‐product of palm oil production. POME can be considered as harmful waste without any treatment. POME, however, has the potential to be a source of low‐cost carbon for lipid production. This study aims to isolate potential oleaginous fungi from POME and to evaluate the ability of lipid production capacity of the purified isolates and commercial oleaginous fungi strains (Aspergillus niger, Aspergillus oryzae and Rhizopus spp.) from POME. POME is converted into lipid via the metabolic pathway of oleaginous fungi, where the lipids can be further trans‐esterified into microbial biodiesel. In this study, two fungal strains are successfully isolated from POME. The combination of Bligh and Dyer with Soxhlet extraction results in better lipid extraction efficiency. A. niger has the highest lipid yield from the cultivation on POME. The projected fuel properties of microbial biodiesel from A. niger are within the limits of Biodiesel Standard. Chemical oxygen demand (COD) removal from POME using A. niger is proven to be effective with 70% COD removal. The production of biodiesel from wastes of the palm oil industry may improve the industry's sustainability through the use of nonfood feedstock coupled with simultaneous bioremediation of POME.

Biodiesel production from lignocellulosic biomass using Yarrowia lipolytica

• Sugarcane bagasse hydrolysates was used as a bio resource for lipid production. • Acid, alkaline and ultra-sonication techniques were attempted in pretreatment of Sugarcane bagasse. • 16.39 g/l of biomass concentration were achieved with Sugarcane bagasse hydrolysates. • In-situ transesterification carried out with the catalyst K2CO3 yields 80% biodiesel. Depletion of hydrocarbons is forcing to find alternative resources to meet the energy demand of the growing population. Microbial biodiesel as a fuel can act as a cheaper and eco-friendly alternative to fossil fuel. Single-cell oil (SCO) consisting of carbon, hydrogen and oxygen grown over the lignocellulosic biomass using oleaginous microorganisms are triacylglycerols which can be converted to biodiesel, with physicochemical properties similar to conventional diesel. However, several cost-effective pretreatment methods are required to utilize lignocellulosic biomasses. The current research study investigates the SCO yield (and biodiesel characteristics) obtained from sugarcane bagasse hydrolysate through various pretreatment techniques. The pretreatment with 4% v/v H 2 SO 4 at 25 min of ultra-sonication provided the best depolymerisation results (based on the glucose concentration). Yarrowia lipolytica was inoculated into the hydrolysates, allowed to grow at 25 °C, pH of 6.5 and rapid mixing for six days yielded biomass of 16.39 g/l. Biodiesel was extracted from the biomass via in-situ and ex-situ transesterification. In-situ transesterification carried out with the catalyst K 2 CO 3 yields 80% biodiesel. In comparison, 63% were achieved with ex-situ transesterification, where lipid extraction was carried out as a first step and transesterified further in the presence of catalyst KOH to obtain biodiesel. The obtained fatty acid methyl esters (FAME) was subjected to FTIR analysis, and the observed physicochemical properties were within the international standards.

Comparison of Ex-Situ and In-Situ Transesterification for the Production of Microbial Biodiesel

Microbial biodiesel is converted from microbial lipids via transesterification process. Most microbial biodiesel studies are focusing on the use of microalgal lipids as feedstock. Apart from using microalgae for lipid biosynthesis, lipids can also be extracted from other oleaginous microorganisms like fungi and yeast. However, there are gaps in the studies of lipid production from filamentous fungi, especially in-situ transesterification process. The aim of this project is to compare in-situ with the ex-situ transesterification of fungal biomass from Aspergillus oryzae. In ex-situ transesterification, two methods of lipid extraction, the Soxhlet extraction and the Bligh and Dyer extraction, were performed. For in-situ transesterification, two methods using different catalysts were investigated. Base-catalyzed in-situ transesterification of fungal biomass resulted on the highest Fatty Acid Methyl Esters (FAME) yield. The base-catalyzed in-situ transesterification was further optimized via Central Composite Design (CCD) of Response Surface Methodology (RSM). The parameters investigated were the catalyst loading, methanol to biomass ratio and reaction time. The optimization showed that the highest FAME yield was at 25.1% (w/w) with 10 minutes reaction time, 5% catalyst and 360:1 of the ratio of the methanol to biomass. Based on Analysis of Variance (ANOVA), the model was found to be significant according to the value of “Prob >F” of 0.0028. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Microorganisms-promoted biodiesel production from biomass: A review

Biodiesel is considered as a potential substitute for fossil fuel due to its renewability, sustainability, environmentally friendliness, and biodegradability, especially with comparable fuel properties to diesel. The chemocatalytic production of biodiesel from plant oils is widely used in industrial production due to its low cost and high conversion rate. However, the disadvantages are high energy consumption and environmentally unfriendly processing such as chemical catalysts, downstream technology and simultaneously produced waste. Therefore, in the past decade, enzyme-catalyzed biodiesel has attracted more attentions due to its sustainability and environmental friendliness. High-cost, enzyme stability and reusability are the main obstacles to the large-scale industrial development of microbial biodiesel. This review first showcases the state-of-the-art of microbial biodiesel production, including (1) lipid accumulation of oleaginous microorganisms from pretreated lignocellulose biomass, and (2) production of biodiesel from microbial oils via transesterification by immobilized lipase. Also, the technological challenges and future developmental trends are discussed, with the goal of providing the possibility of more economical large-scale industrial production. This paper provides opportunities for the sustainable and eco-friendly production of enzymatic biodiesel in the future.

Volatile Fatty Acids from Lipid-Extracted Yeast Provide Additional Feedstock for Microbial Lipid Production

Microbial lipid production from oleaginous yeasts is a promising process for the sustainable development of the microbial biodiesel industry. However, the feedstock cost poses an economic problem for the production of microbial biodiesel. After lipid extraction, yeast biomass can be used as an organic source for microbial biodiesel production. In this study, volatile fatty acids (VFAs), produced via anaerobic digestion of a lipid-extracted yeast (LEY) residue, were utilized as a carbon source for the yeast Cryptococcus curvatus. The response surface methodology was used to determine the initial pH and inoculum volume for the optimal VFA production. The experimental result for VFA concentration was 4.51 g/L at an initial pH of 9 and an inoculation 25%. The optimization results from the response surface methodology showed that the maximal VFA concentration was 4.58 g/L at an initial pH of 8.40 and an inoculation of 39.49%. This study indicates that VFAs from LEY can be used as a carbon source for microbial biodiesel production, with the potential to significantly reduce feedstock costs.

Multi-objective optimization for biomass and lipid production by oleaginous bacteria using vegetable waste as feedstock

In this study, pretreated organic wastes such as waste paper cups, cardboard waste, and vegetable waste were screened for the growth and lipid production of oleaginous bacteria DS-7 (isolated from the dairy effluent scum). The pretreated vegetable waste was found to be the best feedstock for biomass and lipid production by the DS-7. Further, process parameters such as inoculation time, substrate concentration (w/v) (amount of pretreated vegetable waste), pH, and inoculum size were optimized using a multi-objective optimization technique to enhance the biomass and lipid productions. The optimization study successfully enhanced the biomass concentration (g/L) and lipid content (%) by 47.9% and 15.84%, respectively in comparison with the unoptimized state. The biomass and lipid productivities were 42% (1.449 g/L/d) and 51% (1.267 g/L/d) greater than unoptimized conditions. The characteristics of the biodiesel obtained from the valorization of vegetable waste were comparable to the standard. Thus, the vegetable waste can be utilized as a potential feedstock for microbial biodiesel production.

Mixed glycerol and orange peel-based substrate for fed-batch microbial biodiesel production

The aqueous extraction of orange peel waste (OPW), the byproduct of the juice extraction process generated annually in massive amounts (21 Mton), yields a carbohydrate-rich liquid fraction, termed orange peel extract (OPE). Several studies highlight that the combination of glycerol, a biodiesel byproduct, with carbohydrate mixtures might boost microbial lipid production. This study performed first a shaken flask screening of 15 oleaginous yeast strains based on their growth and lipid-producing abilities on OPE- and glycerol-based media. This screening enabled the selection of R. toruloides NRRL 1091 for the assessment of the process transfer in a stirred tank reactor (STR). This assessment relied, in particular, on either single- and double-stage feeding fed-batch (SSF-FB and DSF-FB, respectively) processes where OPE served as the primary medium and nitrogen-containing glycerol-OPE mixtures as the feeding one. The continuous supply mode at low dilution rates (0.02 and 0.01 h−1 for SSF-FB and DSF-FB, respectively) starting from the end of the exponential growth of the initial batch phase enabled the temporal extension of biomass and lipid production. The SSF-FB and DSF-FB processes attained high biomass and lipid volumetric productions (LVP) and ensured significant lipid accumulation on a dry cell basis (YL/X). The SSF-FB process led to LVP of 20.6 g L−1 after 104 h with volumetric productivity (rL) of 0.20 g L−1 h−1 and YL/X of 0.80; the DSF-FB process yielded LVP, rL and YL/X values equal to 15.92 g L−1, 0.11 g L−1 h−1 and 0.65, respectively. The fatty acid profiles of lipids from both fed-batch processes were not significantly different and resembled that of Jatropha oil, a vastly used feedstock for biodiesel production. These results suggest that OPE constitutes an excellent basis for the fed-batch production of R. toruloides lipids, and this process might afford a further option in OPW-based biorefinery.

Microbial biodiesel production from industrial organic wastes by oleaginous microorganisms: Current status and prospects

This review aims to encourage the technical development of microbial biodiesel production from industrial-organic-wastes-derived volatile fatty acids (VFAs). To this end, this article summarizes the current status of several key technical steps during microbial biodiesel production, including (1) acidogenic fermentation of bio-wastes for VFA collection, (2) lipid accumulation in oleaginous microorganisms, (3) microbial lipid extraction, (4) transesterification of microbial lipids into crude biodiesel, and (5) crude biodiesel purification. The emerging membrane-based bioprocesses such as electrodialysis, forward osmosis and membrane distillation, are promising approaches as they could help tackle technical challenges related to the separation and recovery of VFAs from the fermentation broth. The genetic engineering and metabolic engineering approaches could be applied to design microbial species with higher lipid productivity and rapid growth rate for enhanced fatty acids synthesis. The enhanced in situ transesterification technologies aided by microwave, ultrasound and supercritical solvents are also recommended for future research. Technical limitations and cost-effectiveness of microbial biodiesel production from bio-wastes are also discussed, in regard to its potential industrial development. Based on the overview on microbial biodiesel technologies, an integrated biodiesel production line incorporating all the critical technical steps is proposed for unified management and continuous optimization for highly efficient biodiesel production.

Microbial biodiesel production: novel method of utilizing sago wastewater for lipid production using oleaginous yeast, Candida tropicalis ASY1

A study was undertaken to determine the physico-chemical characteristicsof sago wastewater (SWW) from various sago industries in Salem andNamakkal districts of India. Besides, different SWW (raw wastewater,aerobic wastewater, treated wastewater and starch wastewater) from withinthe industry were evaluated. The results concluded that effluents from thisregion are whitish and greyish brown in color with majority supra-colloidalor settable suspended solids with high TS, TSS, and TDS. The ammoniacal,nitrate, and nitrite nitrogen ranged from 2.7 to 6.5, 4.5 to 19.1, and 0.4to 2.8 mg.L-1. The total nitrogen content of SWW samples was ranged from180- 650 mg.L-1. The phosphate level of SWW was very high (640-1096 mg.L-1). The COD and BOD content of SWW from all the industries ranged from2560 to 3200 mg.L-1 and 34000 to 76000 mg.L-1 indicates its high organicnature. SWW effluents are acidic in nature (pH 4.3-5.2). The free cyanide(CN) content was ranged from 1.2 to 5.2 mg.L-1. The treated wastewater hadneutral pH (pH - 6.2), and had a reduced level of EC, starch content, TSS,COD and BOD.

Cost, energy and GHG emission assessment for microbial biodiesel production through valorization of municipal sludge and crude glycerol.

In this study, cost simulations were made based on 20 million L blended biodiesel B-10 production per year using INRS and conventional process. In case of INRS process, microbial lipid was produced by T. oleaginosus using washed municipal secondary sludge fortified with crude glycerol while lipid was extracted from wet biomass using biodegradable surfactant and petroleum-diesel (PD). The conventional process uses commercial substrates for lipid production and organic solvents for lipid extraction from dry biomass. The unit B-10 production cost of INRS process was estimated to be $ 0.72/L for an annual capacity of 20 million L, which is 9.5 times more economical than conventional biodiesel production process. For INRS process, the unit B-10 biodiesel production cost was sensitive to plant capacity and lipid productivity during the fermentation. INRS process exhibited positive net energy gain and positive GHG capture, which proves to be energetically and environmentally viable.

Co-production of single cell oil and gluconic acid using oleaginous Cryptococcus podzolicus DSM 27192

BackgroundThe co-production of single cell oil (SCO) with value-added products could improve the economic viability of industrial SCO production. The newly isolated oleaginous yeast Cryptococcus podzolicus DSM 27192 was able to co-produce SCO intracellularly and gluconic acid (GA) extracellularly. In this study, the metabolic regulation of carbon distribution between SCO and GA through process optimization was comprehensively investigated.ResultsThe carbon flow distribution between SCO and GA was significantly influenced by the cultivation conditions, such as nitrogen sources, glucose concentration and dissolved oxygen concentration. It was found that organic nitrogen sources were beneficial for SCO accumulation, while GA production was decreased. Dissolved oxygen concentration (DOC) was found to enhance SCO accumulation, while high glucose concentration was more favorable for GA accumulation. Hence, a two-stage DOC or glucose concentration-controlled strategy was designed to improve cell growth and direct carbon distribution between SCO and GA. Moreover, C. podzolicus DSM 27192 could degrade its stored lipids to synthesize GA in the late stationary phase, although considerable amounts of glucose remained unconsumed in the culture medium, indicating the importance of fermentation time control in co-production systems. All these observations provide opportunity to favor either the production of SCO or GA or rather their simultaneous production.ConclusionsCo-production of SCO and GA by C. podzolicus DSM 27192 can improve the economical value for microbial lipid-derived biodiesel production. Moreover, the results of the proposed co-production strategy might give guidance for other co-production systems.

Generation of biodiesel from industrial wastewater using oleaginous yeast: performance and emission characteristics of microbial biodiesel and its blends on a compression injection diesel engine.

Microbial-derived biodiesel was tested on a lab scale CI diesel engine for carrying out exhaust emission and performance characteristics. The performance, emission, and combustion characteristics of a single cylinder four stroke fixed compression ratio engine when fueled with microbial bio-diesel and its 10-30% blends with diesel (on a volume basis) were investigated and compared with conventional diesel. The bio-diesel was obtained from microbes which were grown by combining distillery spent wash with lignocellulosic hydrolysate at nutrient deprived conditions. The microbes consumed the wastes and converted the high strength waste water into lipids, which were trans-esterified to form bio-diesel. Testing of microbial bio-diesel blends with ordinary diesel at different loading pressures and the emission characteristics were compared. Results indicate that with increasing of the blends, reduction of HC and CO emissions were observed, whilst brake thermal efficiency maxed out at 20% blending. Further increase of blends showed a tendency of increasing of both emissions in the exhaust stream. The Brake Specific Fuel consumption was observed to decline with blending until 20% and then increased. The nitrogen oxide emissions, however, were found to increase with increasing blend ratios and reached a maximum at 20% blend. The escalation of HC, CO, CO2, and NOx emissions was also observed at higher blending ratios and higher engine loads. The performance studies were able to show that out of the three blends of biodiesel, 20% biodiesel blend was able to deliver the best of reduced hydrocarbon and carbon monoxide emissions, whilst also delivering the highest Brake thermal efficiency and the lowest Brake Specific Fuel consumption.

Integration of microbial biodiesel and bioethanol industries through utilization of vinasse as substrate for oleaginous fungi

The main aim of this work was to assess a conceptual strategy of submerged pelletized growth of Mucor circinelloides in sugarcane vinasse under different conditions aiming at the production of lipids prone to be used in biodiesel syntheses. Industrial vinasse was characterized and then tested in its raw form as culture medium. Relatively high concentrations of lipids were observed (approximately 23%), and biomass accumulation can be enhanced by the addition of corn steep liquor (approximately 5-fold increase when compared to control). Phenolic compounds present in vinasse pose inhibitory effects in biomass and lipid accumulation. The pelletized hyphae then proceeded to a simple sieve separation, on which lipids were extracted in a microwave extraction system, with a resulting fatty acid profile that indicate a potential suitable feedstock for biodiesel production due to the balance of saturated and unsaturated fatty acids.

Microbial biodiesel production: From sucrose-based carbon sources to alkyl esters via enzymatic transesterification

Abstract Sucrose, in contrast to glucose, is a lower-cost carbon source. This manuscript discloses that its use in submerged fungal growth promotes lipids more suitable to biodiesel production due to lower unsaturation indexes. The wild strain of Mucor circinelloides URM 4182, a potential source of microbial lipid, was grown on three sucrose-based carbon sources: commercial brown sugar, sugarcane juice, and sugarcane syrup, achieving biomass accumulation productivities up to 3.62 ± 0.04 g L−1 day−1, and lipid productivities as high as 0.93 ± 0.01 g L−1 day−1. Lipid extraction was performed using ethanol, a green alternative to petroleum-derived solvent, and characterized according to their fatty acid distribution, from which C16:0 and C18:1 stand as the most abundant fatty acids. Extracted lipids were converted to ethyl esters via lipase-catalyzed reactions achieving ester contents up to 97.4% and low contents of mono- and diacylglycerols (1.9% and 1.0%, respectively). The interest in utilizing sucrose-based sources is due to the wide abundance of such feedstock in sugarcane-producing regions, and due to the potential of increasing value to these low-cost carbon sources. The results presented herein demonstrate a simple, yet efficient, process of converting sucrose and its derivatives to microbial biodiesel using green-chemistry processes, such as lipid extraction using ethanol, avoiding the use of harsh and toxic chemicals commonly utilized, and enzyme-catalyzed reactions.

Microbial Biodiesel Production by Direct Transesterification of Rhodotorula glutinis Biomass

(1) Background: Lipids derived from oleaginous microbes have become promising alternative feedstocks for biodiesel. This is mainly because the lipid production rate from microbes is one to two orders of magnitude higher than those of energy crops. However, the conventional process for converting these lipids to biodiesel still requires a large amount of energy and organic solvents; (2) Methods: In this study, an oleaginous yeast, Rhodotorula glutinis, was used for direct transesterification without lipid pre-extraction to produce biodiesel, using sulfuric acid or sodium hydroxide as a catalyst. Such processes decreased the amount of energy and organic solvents required simultaneously; (3) Results: When 1 g of dry R. glutinis biomass was subject to direct transesterification in 20 mL of methanol catalyzed by 0.6 M H2SO4 at 70 °C for 20 h, the fatty acid methyl ester (FAME) yield reached 111%. Using the same amount of biomass and methanol loading but catalyzed by 1 g/L NaOH at 70 °C for 10 h, the FAME yield reached 102%. The acid-catalyzed process showed a superior moisture tolerance; when the biomass contained 70% moisture, the FAME yield was 43% as opposed to 34% of the base-catalyzed counterpart; (4) Conclusions: Compared to conventional transesterification, which requires lipid pre-extraction, direct transesterification not only simplifies the process and shortens the reaction time, but also improves the FAME yield.

Direct Methanolysis of Oleaginous Yeast Biomass (<i>Pseudozyma parantarctica</i>) to Microbial Biodiesel

In this study, intracellular lipids of a novel oleaginous biomass of P. parantarctica were converted to biodiesel directly using simple acid catalyst methanolysis. The optimum condition of this method was investigated. Under optimum conditions (0.1 M H2SO4, 10 h reaction time, 65°C reaction temperature, and 1:20 (w/v) biomass-to-methanol ratio), the yield of crude biodiesel was 93.18 ± 2.09% based on total cellular lipids. The composition of crude biodiesel was C16:C18 fatty acid methyl esters (FAMEs) for 91.91%. Especially, the C18:1 methyl ester was the main FAME (47.10%). In addition, the result showed that this technique could produce the microbial biodiesel from biomass containing high free fatty acids (FFAs) without soap formation. The predicted cetane number and kinematic viscosity of biodiesel were characterized according to ASTM D6751 and EN 14214 standards. Our results indicated that this process produces a good quality biodiesel. Moreover, it can decrease the manufacturing costs of microbial biodiesel production from oleaginous yeast biomass without cell disruption and lipid extraction.

Microbial biodiesel production from oil palm biomass hydrolysate using marine Rhodococcus sp. YHY01

The effect of various biomass derived inhibitors (i.e. furfural, hydroxymethylfurfural (HMF), vanillin, 4-hydroxy benzaldehyde (4-HB) and acetate) was investigated for fatty acid accumulation in Rhodococcus sp. YHY 01. Rhodococcus sp. YHY01 was able to utilize acetate, vanillin, and 4-HB for biomass production and fatty acid accumulation. The IC50 value for furfural (3.1mM), HMF (3.2mM), vanillin (2.0mM), 4-HB (2.7mM) and acetate (3.7mM) was calculated. HMF and vanillin affect fatty acid composition and increase saturated fatty acid content. Rhodococcus sp. YHY 01 cultured with empty fruit bunch hydrolysate (EFBH) as the main carbon source resulted in enhanced biomass (20%) and fatty acid productivity (37%), in compression to glucose as a carbon source. Overall, this study showed the beneficial effects of inhibitory molecules on growth and fatty acid production, and support the idea of biomass hydrolysate utilization for biodiesel production by avoiding complex efforts to remove inhibitory compounds.