Chemical Constituents from the deep-sea-derived Fungus Aureobasidium melanogenum LUO5

Three new C10 and C12 aliphatic δ-lactones (1-3), three new fatty acid methyl esters (4-6), and eight known compounds (7-14) were isolated from the marine Aureobasidium sp. LUO5. Their structures were established by detailed analyses of the NMR, HRESIMS, optical rotation, and ECD data. All isolates were tested for their inhibitory effects on nitric oxide production in LPS-induced BV-2 cells. Notably, compound 4 displayed the strongest inhibitory effect with the IC50 value of 120.3 nM.

Determination of fatty acid methyl esters by two-color two-photon resonance-enhanced femtosecond ionization mass spectrometry

A standard sample mixture containing thirty-seven fatty acid methyl esters (FAMEs) was measured by femtosecond laser ionization mass spectrometry. FAME molecules with double bonds were efficiently ionized via resonance-enhanced two-photon ionization by absorbing the first photon at 206 nm at the edge of the absorption band of the π→π* transition and subsequently ionized by absorbing the second photon at 257 nm. The intensity of the molecular radical ion was enhanced significantly using this two-color ionization scheme, which minimizes the excess energy in the ionized state, when compared with electron ionization mass spectrometry and vacuum-ultraviolet photoionization mass spectrometry. This approach was then used for the reliable identification of FAMEs contained in an actual sample of biofuel.

Extraction and Quantification of Lipids from Plant or Algae

In plants and algae, the glycerolipidome changes in response to environmental modifications. For instance, in phosphate starvation, phospholipids are degraded and replaced by non-phosphorus lipids, and in nitrogen starvation, storage lipids accumulate. In addition to the well-known applications of oil crops for food, algae lipids are becoming a model for potential applications in health, biofuel, and green chemistry and are used as a platform for genetic engineering. It is therefore important to measure accurately and quickly the glycerolipid content in plants and algae. Here we describe the methods to extract the lipid and quantify the fatty acid amount of the lipid extract and the different lipid classes that are present in these samples.

Quantitative Assessment of the Chloroplast Lipidome

In plants and algae, photosynthetic membranes have a unique lipid composition. They differ from all other cellular membranes by their very low amount of phospholipids, besides some phosphatidylglycerol (PG), and high proportion of glycolipids. These glycolipids are the uncharged galactolipids, that is, mono- and digalactosyldiacylglycerol (MGDG and DGDG), and an anionic sulfolipid, that is, sulfoquinovosyldiacylglycerol (SQDG). In all photosynthetic membranes analyzed to date, from cyanobacteria to algae, protists, and plants, the lipid quartet constituted by MGDG, DGDG, SQDG, and PG has been highly conserved, but the composition in fatty acids of these lipids can vary a lot from an organism to another. To better understand the chloroplast biogenesis, it is therefore essential to know their lipid content. Establishing chloroplast lipidome requires first to purify chloroplast from plant or algae tissue. Here we describe the methods to extract the lipid, quantify the lipid amount of the chloroplast, and qualify and quantify the different lipid classes that might be present in these fractions.

Sequential bioconversion of C1-gases (CO, CO2, syngas) into lipids, through the carboxylic acid platform, with Clostridium aceticum and Rhodosporidium toruloides

Syngas (CO, CO2, H2) was effectively bioconverted into lipids in a two-stage process. In the first stage, C1-gases were bioconverted into acetic acid by the acetogenic species Clostridium aceticum through the Wood-Ljungdahl metabolic pathway in a stirred tank bioreactor, reaching a maximum acetic acid concentration of 11.5 g/L, with a production rate of 0.05 g/L·h. Throughout this experiment, samples were extracted at different periods, i.e., different concentrations, to be used in the second stage, aiming at the production of lipids from acetic acid. The yeast Rhodosporidium toruloides, inoculated in the acetogenic medium, was able to efficiently accumulate lipids from acetic acid generated in the first stage. The best results, in terms of lipid content, dry biomass, biomass yield (Y(X/S)) and lipid yield (Y(L/S)) were 39.5% g/g dry cell weight, 3 g/L, 0.35 and 0.107, respectively. In terms of abundance, the lipid profile followed the order: C18:1 > C16:0 > C18:2 > C18:0 > Others. Experiments were also performed to determine the toxicity exerted by high concentrations of acetic acid on R. toruloides, resulting in inhibition at initial acid concentrations around 18 g/L leading to a higher lag phase and being lethal to the yeast at initial acetic acid concentrations around 22 g/L and above. This research paves the way for a novel method of growing oleaginous yeasts to produce sustainable biofuels from syngas or C1-pollutant gases.

A review on the pollution assessment of hazardous materials and the resultant biorefinery products in Palm oil mill effluent

The voluminous nature of palm oil mill effluent (POME) is directly associated with environmental hazards and could be turned into biorefinery products. The POME, rich in BOD, COD, and oil and grease, with few hazardous materials such as siloxanes, fatty acid methyl ester, and phenolic compounds that may significantly increase the risk of violating the effluent quality standards. Recently, the application of chemical and biological risk assessment that can use electrochemical sensors and microalgae-like species has gained paramount attention towards its remediation. This review describes the existing risk assessment for POME and recommends a novel assessment approach using fish species including invasive ones as suitable for identifying the toxicants. Various physico-chemical and biological treatments such as adsorption, coagulation-flocculation, photo-oxidation, solar-assisted extraction, anaerobic digestion, integrated anaerobic-aerobic, and microalgae cultivation has been investigated. This paper offers an overview of anaerobic technologies, with particular emphasis on advanced bioreactors and their prospects for industrial-level applications. To illustrate, palmitic acid and oleic acid, the precursors of fatty acid methyl ester found in POME pave the way to produce biodiesel with 91.45%. Although there are some challenges in attaining production at an economic scale, this review offers some opportunities that could help in overcoming these challenges.

Synthesis and characterization of magnetic bifunctional nano-catalyst for the production of biodiesel from Madhuca indica oil

The reusable magnetic multimetal nano-catalyst (Fe₃O₄.Cs₂O) was synthesized using co-precipitation and incipient wetness impregnation methods. It was used to esterify and transesterify Madhuca indica (M. indica) oil to produce biodiesel with methanol. The prepared catalyst, caesium oxide doped on the nano-magnetite core, was characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Further, the activity of the catalyst was investigated by subjecting it to a biodiesel reaction. To maximize biodiesel conversion, studies were carried out by varying the process variables like catalyst concentration, methanol-to-oil molar ratio, reaction temperature, and reaction time. A maximum conversion of 97.4% was obtained at the holding conditions of 18:1 methanol-to-oil ratio, 7 wt% catalyst loading, 65 °C reaction temperature, and 300 min reaction time. Moreover, the catalyst recyclability study showed that it could be recycled up to 12 cycles with a conversion of 90% and above. The biodiesel's fuel properties were analysed and found to be within the limits of ASTM D6751 standard.

Biodiesel Production from Brassica juncea Using Oleaginous Yeast

The present study explores the potential of Brassica juncea as a low-cost substrate for biodiesel production through the growth of oleaginous yeast. Firstly, the selected lignocellulosic biomass, i.e., Brassica juncea, was thermochemically pretreated using dilute sodium hydroxide. Optimization of thermochemical pretreatment resulted in significant removal of lignin and hemicellulose with 8.4% increase in cellulose content. Further, the sugar hydrolysate of pretreated biomass was used as a substrate for the growth of selected oleaginous yeast (Cryptococcus sp. MTCC 5455). Lipid and biomass production was optimized using central composite design (CCD) based on response surface methodology (RSM). Maximum biomass and lipid content of 32.50 g/L and 11.05 g/L, respectively, was obtained at 30 °C temperature, pH 6.0, and after 5 days of incubation. The oleaginous yeast lipid was further transesterified using immobilized lipase. The highest fatty acid methyl ester 15% FAME yield was obtained after 10 h of enzymatic reaction. Next, the results of specific gravity, viscosity, flash points, and cloud point of obtained biodiesels were conformed to the ASTM D975 standard. Overall, the present study put forth the cost-effective approach for lignocellulosic biomass-based oleaginous lipid production toward the green synthesis of biodiesel.

Quantitation of endotoxin by gas chromatography-mass spectrometry in Neisseria meningitidis serogroups A, C, W, Y and X during polysaccharide purification used in conjugate vaccine

Bacterial lipopolysaccharide (LPS) responsible for endotoxin effect induces inflammatory reactions. The endotoxins are difficult to separate from the gram-negative polysaccharide (PS) during polysaccharide purification. The most common method to quantify LPS is the limulus amebocyte lysate (LAL) test which interferes with the agents used during PS purification. The gas chromatography-mass spectrometry (GC-MS) provides a suitable alternative by estimating lipid-A chain anchored 3-hydroxy fatty acid methyl ester (FAME) to estimate LPS however, there are no reports of its application in natural polysaccharides used for vaccine preparation. The transesterification of LPS and meningococcal PS yielded primary target 3-O-acetylated myristic acid which was detected by GC-MS and provided quantitative estimation of endotoxin. The GC-MS method was found in agreement with the LAL values showing lower endotoxin content< 10Eu/µg in meningococcal C and Y serogroup polysaccharides in comparison to higher endotoxin 177-523 Eu/µg in meningococcal A, W and X serogroups. The high endotoxin content in purified polysaccharide was attributed to it being detected in its intermediate stage by GC-MS unlike the LAL test. Thus GC-MS serves as a valuable method for endotoxin monitoring and quantitation in gram-negative meningococcal intermediate and purified PS during vaccine preparation.

Experimental investigation of biodiesel production from Madhuca longifolia seed through in situ transesterification and its kinetics and thermodynamic studies

The present investigation aims to develop simultaneous extraction and conversion of inedible Madhuca longifolia seed oil into biodiesel by one-step acid-catalyzed in situ transesterification/reactive extraction process. Six different types of pretreatment were used to assess maximum yield of biodiesel. The maximum yield of 96% biodiesel was acquired with ultrasonic pretreatment at 1% moisture content, 0.61 mm seed grain size, 55 °C temperature, 400 rpm stirring speed, 15 wt% catalyst (H₂SO₄) concentration, and with 1:35 seed oil to methanol ratio in a time period of 180 min. This reaction kinetics precedes first order also the finest value of rate constant and activation energy were calculated as 0.003 min^-1 and 14.840 kJ mol^-1. The thermodynamic energy properties ΔG, ΔH, and ΔS are computed as 96457.172 J/mol, 12121.812 J/mol K, and - 257.12 J/mol K correspondingly. The enumerated outcome illustrates a heat absorb non-spontaneous/endergonic and endothermal reaction. The result of proposed work unveils ultrasonic pretreatment escalates the biodiesel efficiency and reactive extraction exemplifies the clean, cost-effective single-step approach for production of biodiesel from non-edible sources.

Discrimination between vegetable oil and animal fat by a metabolomics approach using gas chromatography-mass spectrometry combined with chemometrics

Adulteration of olive oil with the other cheap oils and fats plays an important role in economics and has nutritional benefits. In this work, metabolite profiling was performed using gas chromatography-mass spectrometry to identify and quantify animal fat (lard) adulteration in vegetable oil (olive oil). Principal component analysis could correctly identify and clustering olive oil, sunflower oil, sesame oil, lard, and adulterated samples through the changes in their fatty acid methyl esters (FAMEs) profile. A targeted metabolomics method was then optimized and validated through construction of calibration curves of known FAMSs in olive oil and lard. The method was presented high linearity (R2 > 0.96) and good intra and inter day accuracy and precision (79-101 and 86-102% and 2-7 and 3-7, respectively) for determination of FAMEs. Afterwards the absolute concentration and relative percentage of FAMEs were successfully determined in 12 commercial olive oils and 3 lards samples. Methyl myristate, methyl palmitate, methyl oleate, and methyl stearate were selected as discriminant markers to identify and quantify lard adulteration even at a low level of lard (5%w/w), with errors less than 2% in the comparison of the absolute or relative concentrations of FAMEs using several statistical methods. The proposed methodology allowed us to quantify the FAMEs simultaneously and also could predict small amount of lard in the adulterated olive oil samples.

Feasibility of biodiesel production from waste cooking oil: lab-scale to pilot-scale analysis

In the last few decades, consciousness of fossil fuel resources and increased environmental concerns have given the need for emergence of alternative fuel. Biodiesel is one of the potential renewable energies produced from edible and non-edible biomass which could be a potential alternative for petrol-derived diesel. In this work, initially the process of biodiesel production from waste cooking oil using potassium hydroxide as catalyst and the process parameters were studied in laboratory. The maximum biodiesel yield of 97% was attained at 75 °C with 1 wt% catalyst concentration and oil-methanol molar ratio of 1:06 at 350 rpm and 90 min. Also, these process conditions were used for biodiesel production in the pilot plant and obtained 97% yield. Overall, mass balance for the pilot plant was studied to analyze the product yield loss. The fatty acid methyl ester formation in the plant was confirmed by characterization with FTIR and ¹H NMR. Further, the quality of biodiesel produced was compared for its physiochemical properties with the ASTM standards.

Identification and quantification of dimethyl acetals from plasmalogenic lipids in lamb intramuscular fat under different derivatization procedures

Meat lipids are mostly comprised by triacylglycerols, but small amounts of plasmalogens are also present in intramuscular fat. The purpose of this study was to evaluate the effect of lipid derivatization on the presence of dimethyl acetal (DMA) molecules from plasmalogenic lipids in intramuscular fat samples. Three different methods of methylation were assayed. Acid-catalyzed methanolysis using HCl, the traditional procedure to derivatize meat lipids, was compared to two base-catalyzed methanolysis based on the ISO International standard procedure using either KOH and/or NaOCH₃ which, apparently, are only able to methylate fatty acids from triacylglycerols. DMA compounds were isolated by thin layer chromatography and then identified by gas chromatography-mass spectrometry. The most prominent DMA molecules detected were 16:0 and 18:0, but also minor amounts of monounsaturated and branched-chain DMA were quantified. Acid methylation yielded the highest amounts of DMA. However, the present article demonstrates that ISO standard based methylation procedures could also generate DMA derivatives in considerable quantities, which is not usually considered and may interfere with the determination of fatty acid methyl esters (FAME) from triacylglycerides. The current research warns scientist about possible FAME misidentifying and overestimations in intramuscular fat analysis using basic methylation and the need to consider the presence of DMA in samples that contain plasmalogens.

Lipidomic Analysis of Cancer Cell and Tumor Tissues

Due to their role in cellular structure, energetics, and signaling, characterization of changes in cellular and extracellular lipid composition is of key importance to understand cancer biology. In addition, several mass spectrometry-based profiling as well as imaging studies have indicated that lipid molecules may be useful to augment existing biochemical and histopathological methods for diagnosis, staging, and prognosis of cancer. Therefore, analysis of lipidomic changes associated with cancer cells and tumor tissues can be useful for both fundamental and translational studies. Here, we provide a high-throughput single-extraction-based method that can be used for simultaneous lipidomic and metabolomic analysis of cancer cells or healthy or tumor tissue samples. In this chapter, a modified Bligh-Dyer method is described for extraction of lipids followed by analysis of fatty acid composition by gas chromatography-mass spectrometry (GC-MS) or untargeted lipidomics using electrospray ionization mass spectrometry (ESIMS) coupled with reverse-phase (RP) ultraperformance liquid chromatography (UPLC) followed by multivariate data analysis to identify features of interest.

Stable Isotope Probing of Microbial Phospholipid Fatty Acids in Environmental Samples

Phospholipid fatty acid (PLFA) extracted from environmental samples describe the microbial community pattern and are sensitive to monitor and quantify shifts in the microbial community. Linkage with the stable isotope technique adds a functional perspective and is frequently used to quantify carbon turnover in microbial communities and detect physiological changes. Here we present a PLFA extraction method by using an organic solvent water mixture, followed by lipid separation based on solid-phase extraction and an alkaline methylation. Finally, we provide a protocol for the carbon stable isotope measurements of the extracted fatty acid methyl esters (FAMEs) by gas chromatograph-isotope ratio mass spectrometer (GC-IRMS) and calculation of concentration and δ¹³C_VPDB values.

Conversion of Microbial Lipids to Biodiesel and Basic Lab Tests for Analysis of Fuel-Quality Parameters

This chapter describes lab-scale procedures for the direct conversion of microbial lipids to fatty acid methyl esters (FAMEs) for use as biodiesel fuel. Methods for the gas chromatography analysis of FAME profiles and equations to predict several fuel-quality parameters are detailed herein. This chapter also provides a complete list summarizing each of the fuel quality tests (e.g., sample size and equipment) that are required by ASTM International D6751 regulations for pure biodiesel fuel (B100) or blend stock. Recommendations for the decolorization of microbial lipid sources containing pigments are also included. This resource should provide a guide to basic conversion and characterization of microbial-derived biodiesel fuels and a roadmap for more-detailed testing required to assess commercial feasibility.

Extraction and Quantification of Lipids from Plant or Algae

In plants and algae, the glycerolipidome changes in response to environmental modifications. For instance, in phosphate starvation, phospholipids are degraded and replaced by nonphosphorus lipids and in nitrogen starvation, storage lipids accumulate. In addition to the well-known applications of oil crops for food, algae lipids are becoming a model for potential applications in health, biofuel, and green chemistry and are used as a platform for genetic engineering. It is therefore important to measure accurately and quickly the glycerolipid content in plants and algae. Here we describe the methods to extract the lipid, quantify the fatty acid amount of the lipid extract and to quantify the different lipid classes that are present in these samples.

Quantitative Assessment of the Chloroplast Lipidome

In plants and algae, photosynthetic membranes have a unique lipid composition. They differ from all other cellular membranes by their very low amount of phospholipids, besides some phosphatidylglycerol (PG), and high proportion of glycolipids. These glycolipids are the uncharged galactolipids, i.e., monogalactosyldiacylglycerol and digalactosyldiacylglycerol (MGDG and DGDG), and an anionic sulfolipid, i.e., sulfoquinovosyldiacylglycerol (SQDG). In all photosynthetic membranes analyzed to date, from cyanobacteria to algae, protists, and plants, the lipid quartet constituted by MGDG, DGDG, SQDG, and PG has been highly conserved but the composition in fatty acids of these lipids can vary a lot from an organism to another. To better understand chloroplast biogenesis, it is therefore essential to know their lipid content. Establishing chloroplast lipidome requires first to purify chloroplast from plant or algae tissue. Here we describe the methods to extract lipids, quantify the lipids of the chloroplast, and qualify and quantify the different lipid classes that might be present in these fractions.

Production of FAME and FAEE via Alcoholysis of Sunflower Oil by Eversa Lipases Immobilized on Hydrophobic Supports

The performance of two new commercial low-cost lipases Eversa® Transform and Eversa® Transform 2.0 immobilized in different supports was investigated. The two lipases were adsorbed on four different hydrophobic supports. Interesting results were obtained for both lipases and for the four supports. However, the most active derivative was prepared by immobilization of Eversa® Transform 2.0 on Sepabeads C-18. Ninety-nine percent of fatty acid ethyl ester was obtained, in 3 h at 40 °C, by using hexane as solvent, a molar ratio of 4:1 (ethanol/oil), and 10 wt% of immobilized biocatalyst. The final reaction mixture contained traces of monoacylglycerols but was completely free of diacylglycerols. After four reaction cycles, the immobilized biocatalyst preserved 75% of activity. Both lipases immobilized in Sepabeads C-18 were very active with ethanol and methanol as acceptors, but they were much more stable in the presence of ethanol.

Total Fatty Acid Content Determination of Whole Microalgal Biomass Using In Situ Transesterification

The aliphatic chains of fatty acids are the most prominent and potentially the highest value precursor constituents of algal biomass, and thus accurately quantifying the algal biomass total fatty acid content is a prerequisite for comparing algal strains, growth conditions, and processes. Direct, acid-catalyzed transesterification of whole microalgal biomass is a simple, effective, and widely used method to determine the fatty acid content in whole algal biomass. Such a direct transesterification procedure typically covers the following steps: first, solubilizing the lipids in the biomass matrix and then liberating the fatty acids to make these available for catalytic upgrading to fatty acid methyl esters (FAMEs), subsequent extraction into hexane, and then quantification by gas chromatography. The method we describe here requires less than 10 mg of biomass per sample and is considered high-throughput and highly accurate.

Effect of supercritical carbon dioxide on the enzymatic production of biodiesel from waste animal fat using immobilized Candida antarctica lipase B variant

BACKGROUND

Waste animal fat is a promising feedstock to replace vegetable oil that widely used in commercial biodiesel process, however the high content of free fatty acid in waste fat makes it unfeasible to be processed with commercial base-catalytic process. Enzymatic process is preferable to convert waste fat into biodiesel since enzyme can catalyze both esterification of free fatty acid and transesterification of triglyceride. However, enzymatic reaction still has some drawbacks such as lower reaction rates than base-catalyzed transesterification and the limitation of reactant concentration due to the enzyme inhibition of methanol. Supercritical CO₂ is a promising reaction media for enzyme-catalyzed transesterification to overcome those drawbacks.

RESULT

The transesterification of waste animal fat was carried out in supercritical CO₂ with varied concentration of feedstock and methanol in CO₂. The CO₂ to feedstock mass ratio of 10:1 showed the highest yield compared to other ratios, and the highest FAME yield obtained from waste animal fat was 78%. The methanol concentration effect was also observed with variation 12%, 14%, and 16% of methanol to feedstock ratio. The best yield was 87% obtained at the CO₂ to feedstock ratio of 10: 1 and at the methanol to feedstock ratio of 14% after 6 h of reaction.

CONCLUSION

Enzymatic transesterification to produce biodiesel from waste animal fat in supercritical fluid media is a potential method for commercialization since it could enhance enzyme activity due to supercritical fluid properties to remove mass transfer limitation. The high yield of FAME when using high mass ratio of CO₂ to oil showed that supercritical CO₂ could increase the reaction and mass transfer rate while reducing methanol toxicity to enzyme activity. The increase of methanol concentration also increased the FAME yield because it might shift the reaction equilibrium to FAME production. This finding describes that the application of supercritical CO₂ in the enzymatic reaction enables the application of simple process such as a packed-bed reactor.

Diversity and functional properties of acid-tolerant bacteria isolated from tea plantation soil of Assam

In this study, we report on the bacterial diversity and their functional properties prevalent in tea garden soils of Assam that have low pH (3.8-5.5). Culture-dependent studies and phospholipid fatty acid analysis revealed a high abundance of Gram-positive bacteria. Further, 70 acid-tolerant bacterial isolates characterized using a polyphasic taxonomy approach could be grouped to the genus Bacillus, Lysinibacillus, Staphylococcus, Brevundimonas, Alcaligenes, Enterobacter, Klebsiella, Escherichia, and Aeromonas. Among the 70 isolates, 47 most promising isolates were tested for their plant growth promoting activity based on the production of Indole Acetic Acid (IAA), siderophore, and HCN as well as solubilization of phosphate, zinc, and potassium. Out of the 47 isolates, 10 isolates tested positive for the entire aforesaid plant growth promoting tests and further tested for quantitative analyses for production of IAA, siderophore, and phosphate solubilization at the acidic and neutral condition. Results indicated that IAA and siderophore production, as well as phosphate solubilization efficiency of the isolates decreased significantly (P ≤ 0.05) in the acidic environment. This study revealed that low soil pH influences bacterial community structure and their functional properties.

In Situ Enzymatic Conversion of Nannochloropsis oceanica IMET1 Biomass into Fatty Acid Methyl Esters

Conventionally, production of methyl ester fuels from microalgae occurs through an energy-intensive two-step chemical extraction and transesterification process. To improve the energy efficiency, we performed in situ enzymatic conversion of whole algae biomass from an oleaginous heterokont microalga Nannochloropsis oceanica IMET1 with the immobilized lipase from Candida antarctica. The fatty acid methyl ester yield reached 107.7% for dry Nannochloropsis biomass at biomass to t-butanol to methanol weight ratio of 1:2:0.5 and a reaction time of 12 h at 25 °C, representing the first report of efficient whole algae biomass conversion into fatty acid methyl esters at room temperature. Different forms of algal biomass including wet Nannochloropsis biomass were tested. The maximum yield of wet biomass was 81.5%. Enzyme activity remained higher than 95% after 55 days of treatment (equal to 110 cycles of reaction) under the conditions optimized for dry algae biomass conversion. The low reaction temperature, high enzyme stability, and high yield from this study indicate in situ enzymatic conversion of dry algae biomass may potentially be used as an energy-efficient method for algal methyl ester fuel production while allowing co-product recovery.

A novel microalgal lipid extraction method using biodiesel (fatty acid methyl esters) as an extractant

Although microalgae are considered promising renewable sources of biodiesel, the high cost of the downstream process is a significant obstacle in large-scale biodiesel production. In this study, a novel approach for microalgal biodiesel production was developed by using the biodiesel as an extractant. First, wet microalgae with 70% water content were incubated with a mixture of biodiesel/methanol and penetration of the mixture through the cell membrane and swelling of the lipids contained in microalgae was confirmed. Significant increases of lipid droplets were observed by confocal microscopy. Second, the swelled lipid droplets in microalgae were squeezed out using mechanical stress across the cell membrane and washed with methanol. The lipid extraction efficiency reached 68%. This process does not require drying of microalgae or solvent recovery, which the most energy-intensive step in solvent-based biodiesel production.

Isolation, phenotypic characterization and genome wide analysis of a Chlamydomonas reinhardtii strain naturally modified under laboratory conditions: towards enhanced microalgal biomass and lipid production for biofuels

BACKGROUND

Microalgal strain development through genetic engineering has received much attention as a way to improve the traits of microalgae suitable for biofuel production. However, there are still some limitations in application of genetically modified organisms. In this regard, there has been recent interest in the isolation and characterization of superior strains naturally modified and/or adapted under a certain condition and on the interpretation of phenotypic changes through the whole genome sequencing.

RESULTS

In this study, we isolated and characterized a novel derivative of C. reinhardtii, whose phenotypic traits diverged significantly from its ancestral strain, C. reinhardtii CC-124. This strain, designated as CC-124H, displayed cell population containing increased numbers of larger cells, which resulted in an increased biomass productivity compared to its ancestor CC-124. CC-124H was further compared with the CC-124 wild-type strain which underwent long-term storage under low light condition, designated as CC-124L. In an effort to evaluate the potential of CC-124H for biofuel production, we also found that CC-124H accumulated 116 and 66% greater lipids than that of the CC-124L, after 4 days under nitrogen and sulfur depleted conditions, respectively. Taken together, our results revealed that CC-124H had significantly increased fatty acid methyl ester (FAME) yields that were 2.66 and 1.98 times higher than that of the CC-124L at 4 days after the onset of cultivation under N and S depleted conditions, respectively, and these higher FAME yields were still maintained by day 8. We next analyzed single nucleotide polymorphisms (SNPs) and insertion/deletions (indels) based on the whole genome sequencing. The result revealed that of the 44 CDS region alterations, 34 resulted in non-synonymous substitutions within 33 genes which may mostly be involved in cell cycle, division or proliferation.

CONCLUSION

Our phenotypic analysis, which emphasized lipid productivity, clearly revealed that CC-124H had a dramatically enhanced biomass and lipid content compared to the CC-124L. Moreover, SNPs and indels analysis enabled us to identify 34 of non-synonymous substitutions which may result in phenotypic changes of CC-124H. All of these results suggest that the concept of adaptive evolution combined with genome wide analysis can be applied to microalgal strain development for biofuel production.

Nickel oxide nanoparticle-based method for simultaneous harvesting and disruption of microalgal cells

Microalgae biodiesel is considered one of the most promising renewable fuels. However, the high cost of the downstream process is a major barrier to large-scale microalgal lipid production. In this study, a novel approach based on nickel oxide nanoparticles (NiO NPs) was developed and its effectiveness for simultaneous harvesting and cell disruption in microalgal lipid production was determined. NiO NPs exhibited a microalgal harvesting efficiency of 98.75% in 1min at pH 7. Moreover, after treating with NiO NPs for 96h, the lipid extraction efficiency of microalgae (with 80% water content) reached 91.08% and was 208.37% compared to that without NiO treatment. This approach is simple and does not necessitate drying; furthermore, no equipment with high energy consumption was required.

Synthesis of fatty acid methyl ester from the transesterification of high- and low-acid-content crude palm oil (Elaeis guineensis) and karanj oil (Pongamia pinnata) over a calcium-lanthanum-aluminum mixed-oxides catalyst

The synthesis of fatty acid methyl ester (FAME) from the high- and low-acid-content feedstock of crude palm oil (CPO) and karanj oil (KO) was conducted over CaO-La2O3-Al2O3 mixed-oxide catalyst. Various reaction parameters were investigated using a batch reactor to identify the best reaction condition that results in the highest FAME yield for each type of oil. The transesterification of CPO resulted in a 97.81% FAME yield with the process conditions of 170°C reaction temperature, 15:1 DMC-to-CPO molar ratio, 180min reaction time, and 10wt.% catalyst loading. The transesterification of KO resulted in a 96.77% FAME yield with the conditions of 150°C reaction temperature, 9:1 DMC-to-KO molar ratio, 180min reaction time, and 5wt.% catalyst loading. The properties of both products met the ASTM D6751 and EN 14214 standard requirements. The above results showed that the CaO-La2O3-Al2O3 mixed-oxide catalyst was suitable for high- and low-acid-content vegetable oil.

Improvement in lipids extraction processes for biodiesel production from wet microalgal pellets grown on diammonium phosphate and sodium bicarbonate combinations

Biomass productivity and growth kinetics for microalgae grown on sodium bicarbonate and diammonium phosphate were investigated. Different carbon and nitrogen ratios have shown different growth rates and biomass productivity and C:N ratio 50:10 as mgL(-1) has shown the best production than all. For effective lipids extraction from biomass thermolysis and sonolysis were carried out from wet biomass. Sonolysis at 2.3W intensity for 5min has released 8.58mg at neutral pH. More quantity of lipids was extracted when extraction was made at pH 4 and 10 which resulted 9mg and 9.28mg lipids respectively. Thermal treatment at 100°C for 10min has released 12.82mg lipid at neutral pH. In the same thermolysis at pH 4 and 10 more quantity of lipids was extracted which were 15.16mg and 14.81mg respectively. Finally transesterified lipids were analyzed through GC-MS for FAME composition analysis.

Feasibility study of biodiesel production using lipids of Hermetia illucens larva fed with organic waste

Hermetia illucens larvae by nature are a decomposer which fed on organic wastes. This study explores the potential of producing biodiesel using lipids from H. illucens larvae. Three types of organic wastes (sewage sludge, fruit waste and palm decanter cake from oil palm mill) were selected based on considerable generation and disposal concern in the area of study as well as lack of investigations as feed for Hermetia illucens larvae in current literatures. Growth rate of the larvae was determined with studying the changes in the biomass per day. H. illucens larvae fed with fruit waste and palm decanter cake have shown growth rates of 0.52±0.02 and 0.23±0.09 g d(-1), respectively. No positive sign of growth were observed in the larvae fed with treated sewage sludge (-0.04±0.01 g d(-1)). Biodiesel as fatty acid methyl ester (FAME) was synthesized by transesterification of the larvae lipid using sulphuric acid as catalyst in methanol. FAME produced was ascertained using ATR-FTIR spectroscopy and GC-MS. The main compositions of fatty acid were found to be C12:0, C16:0 and C18:1n9c. Fatty acid composition of C12:0 fed with fruit waste, sewage sludge and palm decanter was found to be most abundant in the larvae lipid. The amount of C12:0 obtained was 76.13%, 58.31% and 48.06%, respectively. In addition, fatty acid of C16:0 was attained at 16.48% and 25.48% fed with sewage sludge and palm decanter, respectively. Based on the findings, FAME derived from larvae lipids is feasible to be used for biodiesel production.

Synthesis and characterization of carbon cryogel microspheres from lignin-furfural mixtures for biodiesel production

The aim of this work was to study the potential of biofuel and biomass processing industry side-products as acid catalyst. The synthesis of carbon cryogel from lignin-furfural mixture, prepared via sol-gel polycondensation at 90°C for 0.5h, has been investigated for biodiesel production. The effect of lignin to furfural (L/F) ratios, lignin to water (L/W) ratios and acid concentration on carbon cryogel synthesis was studied. The carbon cryogels were characterized and tested for oleic acid conversion. The thermally stable amorphous spherical carbon cryogel has a large total surface area with high acidity. Experimental results revealed the optimum FAME yield and oleic acid conversion of 91.3wt.% and 98.1wt.%, respectively were attained at 65°C for 5h with 5wt.% catalyst loading and 20:1 methanol to oleic acid molar ratio. Therefore, carbon cryogel is highly potential for heterogeneous esterification of free fatty acid to biodiesel.

Sedimentary organic biomarkers suggest detrimental effects of PAHs on estuarine microbial biomass during the 20th century in San Francisco Bay, CA, USA

Hydrocarbon contaminants are ubiquitous in urban aquatic ecosystems, and the ability of some microbial strains to degrade certain polycyclic aromatic hydrocarbons (PAHs) is well established. However, detrimental effects of petroleum hydrocarbon contamination on nondegrader microbial populations and photosynthetic organisms have not often been considered. In the current study, fatty acid methyl ester (FAME) biomarkers in the sediment record were used to assess historical impacts of petroleum contamination on microbial and/or algal biomass in South San Francisco Bay, CA, USA. Profiles of saturated, branched, and monounsaturated fatty acids had similar concentrations and patterns downcore. Total PAHs in a sediment core were on average greater than 20× higher above ∼200 cm than below, which corresponds roughly to the year 1900. Isomer ratios were consistent with a predominant petroleum combustion source for PAHs. Several individual PAHs exceeded sediment quality screening values. Negative correlations between petroleum contaminants and microbial and algal biomarkers - along with high trans/cis ratios of unsaturated FA, and principle component analysis of the PAH and fatty acid records - suggest a negative impacts of petroleum contamination, appearing early in the 20th century, on microbial and/or algal ecology at the site.

Effects of overexpression of a bHLH transcription factor on biomass and lipid production in Nannochloropsis salina

BACKGROUND

Microalgae are considered promising alternative energy sources because they consume CO2 and accumulate large amounts of lipids that can be used as biofuel. Nannochloropsis is a particularly promising microalga due to its high growth rate and lipid content, and the availability of genomic information. Transcription factors (TFs) are global regulators of biological pathways by up- or down-regulation of related genes. Among these, basic helix-loop-helix (bHLH) TFs regulate growth, development, and stress responses in plants and animals, and have been identified in microalgae. We identified two bHLH TFs in the genome of N. salina CCMP1776, NsbHLH1, and NsbHLH2, and characterized functions of NsbHLH2 that may be involved in growth and nutrient uptake.

RESULTS

We obtained NsbHLH2 overexpressing transformants of N. salina CCMP1776 by particle bombardment and confirmed that these were stable transformants. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting using antibodies against the FLAG tag that was attached at the end of the coding sequence confirmed the expression of the NsbHLH2 protein under various culture conditions. The qRT-PCR results also indicated that the endogenous and transgenic expression of NsbHLH2 was reduced under stressed conditions. Overexpression of NsbHLH2 led to increased growth rate in the early growth period, and concomitantly higher nutrient uptake, than wild type (WT). These enhanced growth and nutrient uptake resulted in increased productivities of biomass and FAME. For example, one of the transformants, NsbHLH2 3-6, showed increased biomass productivity by 36 % under the normal condition, and FAME productivity by 33 % under nitrogen limitation condition. Conclusively, the improved growth in the transformants can be associated with the enhanced nutrient uptake. We are currently assessing their potential for scale-up cultivation with positive outcomes.

CONCLUSION

Overexpression of NsbHLH2 led to enhanced growth rate and nutrient uptake during the early growth phase, and increased biomass and FAME productivity, especially in the later period under normal and stressed conditions. Based on these results, we postulate that NsbHLH2 can be employed for the industrial production of biodiesel from N. salina.

Microbial biodiesel production by direct methanolysis of oleaginous biomass

Biodiesel is usually produced by the transesterification of vegetable oils and animal fats with methanol, catalyzed by strong acids or bases. This study introduces a novel biodiesel production method that features direct base-catalyzed methanolysis of the cellular biomass of oleaginous yeast Rhodosporidium toruloides Y4. NaOH was used as catalyst for transesterification reactions and the variables affecting the esterification level including catalyst concentration, reaction temperature, reaction time, solvent loading (methanol) and moisture content were investigated using the oleaginous yeast biomass. The most suitable pretreatment condition was found to be 4gL(-1) NaOH and 1:20 (w/v) dried biomass to methanol ratio for 10h at 50°C and under ambient pressure. Under these conditions, the fatty acid methyl ester (FAME) yield was 97.7%. Therefore, the novel method of direct base-catalyzed methanolysis of R. toruloides is a much simpler, less tedious and time-consuming, process than the conventional processes with higher FAME (biodiesel) conversion yield.

Cationic surfactant-based method for simultaneous harvesting and cell disruption of a microalgal biomass

Microalgae are one of the most promising sustainable energy sources for biodiesel production. However, the high costs of the downstream process are a major bottleneck for commercial-scale production of biodiesel from a microalgal biomass. A novel approach called the cationic surfactant-based harvesting and cell disruption (CSHD) method was studied to determine its effectiveness in simultaneous microalgal biomass harvesting and cell disruption. Using CSHD, the harvesting efficiency reached more than 91% in less than 5 min and 97% in 90 min. Moreover, CSHD exhibited a powerful ability to disrupt the cells; the lipid recovery was increased 133% compared to not using CSHD. CSHD allowed the extraction of up to 100% of the total lipids from a wet microalgal biomass with 80% water content. All of these results were achieved without using energy-intensive equipment. Altogether, our results suggest that CSHD is an energy-efficient technique for the downstream process of microalgal lipid production.

Patterns of diversity in plant and soil microbial communities along a productivity gradient in a Michigan old-field

The relationship between plant diversity and productivity has received much attention in ecology, but the relationship of these factors to soil microbial communities has been little explored. The carbon resources that support soil microbial communities are primarily derived from plants, so it is likely that the soil microbial community should respond to changes in plant diversity or productivity, particularly if the plant community affects the quality or quantity of available carbon. We investigated the relationship of plant diversity and productivity to the composition of the soil microbial community along a topographic gradient in a mid-successional old-field in southwestern Michigan. Soil moisture, soil inorganic N, and plant biomass increased from the top to the base of the slope, while light at ground level decreased along this same gradient. We characterized the changes in resource levels along this gradient using an index of productivity that incorporated light levels, soil N, soil moisture, and plant biomass. Average plant species richness declined with this productivity index and there were associated compositional changes in the plant community along the gradient. The plant community shifted from predominantly low-growing perennial forbs at low productivities to perennial grasses at higher productivities. Although there was variation in the structure of the soil microbial community [as indicated by fatty acid methyl ester (FAME) profiles], changes in the composition of the soil microbial community were not correlated with plant productivity or diversity. However, microbial activity [as indicated by Biolog average well color development and substrate-induced respiration (SIR)] was positively correlated with plant productivity. The similarity between patterns of plant biomass and soil microbial activity suggests that either plant productivity is driving microbial productivity or that limiting resources for each of these two communities co-vary.