Dry Cell Weight Research Articles

Biosynthesis of 3-hydroxydecanoate (3HD) and 3-hydroxydodecanoate (3HDd) in the polyhydroxyalkanoate copolymeric ester chain by Pseudomonas aeruginosa MCC 5300 using oleic acid as a carbon source

The application of non-biodegradable plastics has raised severe environmental concerns over the past few decades. The medium chain length polyhydroxyalkanoates (mcl-PHA) are biodegradable elastomeric polymers produced by the bacteria Pseudomonas, that can potentially solve this crisis. The industrial production of mcl-PHA is limited by low PHA yield of wild bacterial strains and the increased time the bacteria takes to achieve maximum PHA yield. Hence the present study focuses on the early PHA production in Pseudomonas aeruginosa MCC 5300. Pseudomonas aeruginosa MCC 5300 can grow to a high biomass and produce PHA within a short duration of 16 h of growth, reaching up to 75.6 % cell dry weight in media containing only oleic acid as a carbon source. A high amount of PHA production in such a short time was not reported in any wild-type bacteria cultured in nutrient-defined media. The mcl-PHA was a copolymer of 3-hydroxydecanoate and 3-hydroxydodecanoate.

Poly-3-hydroxybutyrate production from acetate by recombinant Pseudomonas stutzeri with blocked L-leucine catabolism and enhanced growth in acetate.

Acetate is a low-cost feedstock for the production of different bio-chemicals. Electrochemical reduction of CO2 into acetate and subsequent acetate fermentation is a promising method for transforming CO2 into value-added chemicals. However, the significant inhibitory effect of acetate on microbial growth remains a barrier for acetate-based biorefinery. In this study, the deletion of genes involved in L-leucine degradation was found to be beneficial for the growth of Pseudomonas stutzeri A1501 in acetate. P. stutzeri (Δpst_3217), in which the hydroxymethylglutaryl-CoA lyase catalyzing β-hydroxy-β-methylglutaryl-CoA into acetyl-CoA and acetoacetate was deleted, grew faster than other mutants and exhibited increased tolerance to acetate. Then, the genes phbCAB from Ralstonia eutropha H16 for poly-3-hydroxybutyrate (PHB) biosynthesis were overexpressed in P. stutzeri (∆pst_3217) and the recombinant strain P. stutzeri (∆pst_3217-phbCAB) can accumulate 0.11g L-1 PHB from commercial acetate. Importantly, P. stutzeri (∆pst_3217-phbCAB) can also use CO2-derived acetate to produce PHB and the accumulated PHB accounted for 5.42% (w/w) of dried cell weight of P. stutzeri (∆pst_3217-phbCAB).

Yeast Lipids from Crude Glycerol Media and Utilization of Lipid Fermentation Wastewater as Maceration Water in Cultures of Edible and Medicinal Mushrooms

Four wild “red” yeast strains (Rhodosporidium kratochvilovae FMCC Y70, R. toruloides NRRL Y-27013, R. toruloides NRRL Y-17902 and R. toruloides NRRL Y-6985) were cultured in shake flasks on industrial glycerol at an initial substrate (Gly0) concentration ≈ 50 g/L under nitrogen limitation. Strains NRRL Y-27013, NRRL Y-17902 and NRRL Y-6985 presented appreciable dry cell weight (DCW) and lipid synthesis (DCW up to 18–19 g/L containing lipids in quantities ≈ 47%, w/w). Strains NRRL Y-27013 and NRRL Y-6985 were further tested in higher Gly0 concentrations (≈90 g/L and ≈110 g/L) with the same initial nitrogen quantity as in the first (“screening”) experiment. Both strains, despite the high Gly0 concentrations and C/N ratios (up to 120 moles/moles) imposed, presented significant DCW production (up to c. 29.0–29.5 g/L). Yeast biomass contained significant lipid (42–43%, w/w) and endopolysaccharide (up to 42%, w/w) quantities. Both lipids and endopolysaccharide quantities (in % w/w) noticeably increased as a response to the imposed nitrogen limitation. Lipids containing mainly oleic and palmitic acids constituted ideal candidates for biodiesel synthesis. Thereafter, the wastewaters derived from the lipid production process (lipid fermentation wastewaters—LFWs) were used as maceration waters in cultivations of edible and medicinal fungi, where novel (non-conventional) substrates were used in the performed cultures. CW (coffee residue + wheat straw), CB (coffee residue + beech wood shavings), OW (olive crop + wheat straw), OB (olive crop + beech wood shavings), RW (rice husk + wheat straw) and RB (rice husk + beech wood shavings) were soaked/sprayed with LFWs or tap water and utilized in the cultivation of Pleurotus, Ganoderma and Lentinula mushrooms. The impact of LFWs on the mycelial growth rate (mm/d) and biomass production was evaluated. The results show that regardless of the wetting method, the highest growth rates (6.2–6.6 mm/d) were noticed on RW and RB for Pleurotus eryngii and Ganoderma resinaceum, on OW, OB and RW for Ganoderma applanatum and on RW, OW and OB for Lentinula edodes. Nevertheless, high biomass production was obtained on substrates soaked with LFWs for Pleurotus ostreatus (RW: 443 mg/g d.w.), L. edodes (RB: 238 mg/g d.w.) and Ganoderma lucidum (RW: 450 mg/g d.w.). Overall, this study demonstrates the possibility of the industrial conversion of low-value agro-waste to mycelial mass and eventually to important food products.

Soft sensor based on Raman spectroscopy for the in-line monitoring of metabolites and polymer quality in the biomanufacturing of polyhydroxyalkanoates.

Polyhydroxyalkanoates (PHA) are among the most promising bio-based alternatives to conventional petroleum-based plastics. These biodegradable polyesters can in fact be produced by fermentation from bacteria like Cupriavidus necator, thus reducing the environmental footprint of the manufacturing process. However, ensuring consistent product quality attributes is a major challenge of biomanufacturing. To address this issue, the implementation of real-time monitoring tools is essential to increase process understanding, enable a prompt response to possible process deviations and realize on-line process optimization. In this work, a soft sensor based on in situ Raman spectroscopy was developed and applied to the in-line monitoring of PHA biomanufacturing. This strategy allows the collection of quantitative information directly from the culture broth, without the need for sampling, and at high frequency. In fact, through an optimized multivariate data analysis pipeline, this soft sensor allows monitoring cell dry weight, as well as carbon and nitrogen source concentrations with root mean squared errors (RMSE) equal to 3.71, 7 and 0.03 g/L, respectively. In addition, this tool allows the in-line monitoring of intracellular PHA accumulation, with an RMSE of 14 gPHA/gCells. For the first time, also the number and weight average molecular weights of the polymer produced could be monitored, with RMSE of 8.7E4 and 11.6E4 g/mol, respectively. Overall, this work demonstrates the potential of Raman spectroscopy in the in-line monitoring of biotechnology processes, leading to the simultaneous measurement of several process variables in real time without the need of sampling and labor-intensive sample preparations.

Performance and robustness analysis reveals phenotypic trade-offs in yeast.

To design strains that can function efficiently in complex industrial settings, it is crucial to consider their robustness, that is, the stability of their performance when faced with perturbations. In the present study, we cultivated 24 Saccharomyces cerevisiae strains under conditions that simulated perturbations encountered during lignocellulosic bioethanol production, and assessed the performance and robustness of multiple phenotypes simultaneously. The observed negative correlations confirmed a trade-off between performance and robustness of ethanol yield, biomass yield, and cell dry weight. Conversely, the specific growth rate performance positively correlated with the robustness, presumably because of evolutionary selection for robust, fast-growing cells. The Ethanol Red strain exhibited both high performance and robustness, making it a good candidate for bioproduction in the tested perturbation space. Our results experimentally map the robustness-performance trade-offs, previously demonstrated mainly by single-phenotype and computational studies.

Modeling the Effect of Temperature on Ethanol Fermentation Using Saccharomyces Cerevisiae CSI-1 by Genetic Programming

In this study, genetic programming (GP) was the systematic method used to identify the structure and parameters of a mathematical model for ethanol fermentation. The mathematical model simulated the effect of temperature on the kinetics of batch ethanol fermentation and helped to find out the optimum temperature for the better performance of the process. Saccharomyces cerevisiae CSI-1 growing in cane molasses-based media was the microorganism used in all the experiments. Achieving the model’s precision in describing the experimental observations involved the estimation of its structure (non-linear principally) and its constant parameters. The model found describes the fermentation kinetics and showed a fair prediction for Dry cell weight (DCW), Colony forming units/mL (CFU/mL), Residual sucrose (RS), Residual glucose (RG) and Ethanol concentration (E). The model was used to optimize the operating conditions of the process. The predictions from the model in terms of Mean Square Error (MSE) and Sum Squared Error (SSE) fitted the experimental data well with fitness values in a range of R2 ? 0:92.

Outdoor pilot-scale cultivation and techno economic assessment of a novel omega-3 eicosapentaenoic acid over-producing Nannochloropsis oculata strain

Nannochloropsis oculata is a microalga that produces a significant amount of eicosapentaenoic acid (EPA). Cultivating strains in photobioreactors commercially can be challenging. We cultivated a mutant N. oculata strain, capable of accumulating >40 % EPA more than the wild-type strain at laboratory scale, in an outdoor 300 L pilot-scale photobioreactor, in the U.K. The mutant N. oculata recorded the highest amount of EPA quantity at 129.87 mg/g dry cell weight (DCW) compared to the wild-type strain, which accumulated 75.43 mg/g DCW. A techno-economic assessment (TEA) evaluated the feasibility of the study. Using specific combined cultivation scenarios, the process resulted in a positive net present value (NPV) and return on investment (ROI) at £52,156,484.46 and 607.22 % after 10 years, respectively. The TEA of the improved EPA quantity by M1 N. oculata showed the high processing cost could be overcome by high yields and an optimised operational strategy.

Description and Characterization of the Odontella aurita OAOSH22, a Marine Diatom Rich in Eicosapentaenoic Acid and Fucoxanthin, Isolated from Osan Harbor, Korea.

Third-generation biomass production utilizing microalgae exhibits sustainable and environmentally friendly attributes, along with significant potential as a source of physiologically active compounds. However, the process of screening and localizing strains that are capable of producing high-value-added substances necessitates a significant amount of effort. In the present study, we have successfully isolated the indigenous marine diatom Odontella aurita OAOSH22 from the east coast of Korea. Afterwards, comprehensive analysis was conducted on its morphological, molecular, and biochemical characteristics. In addition, a series of experiments was conducted to analyze the effects of various environmental factors that should be considered during cultivation, such as water temperature, salinity, irradiance, and nutrients (particularly nitrate, silicate, phosphate, and iron). The morphological characteristics of the isolate were observed using optical and electron microscopes, and it exhibited features typical of O. aurita. Additionally, the molecular phylogenetic inference derived from the sequence of the small-subunit 18S rDNA confirmed the classification of the microalgal strain as O. aurita. This isolate has been confirmed to contain 7.1 mg g-1 dry cell weight (DCW) of fucoxanthin, a powerful antioxidant substance. In addition, this isolate contains 11.1 mg g-1 DCW of eicosapentaenoic acid (EPA), which is one of the nutritionally essential polyunsaturated fatty acids. Therefore, this indigenous isolate exhibits significant potential as a valuable source of bioactive substances for various bio-industrial applications.

Selective screening Lactobacillus spp. against Escherichia coli and Salmonella Typhimurium and optimizing a cane molasses-based medium with Lactobacillus acidophilus as a guiding model

BackgroundThe overuse of antibiotics in livestock farming has led to the emergence of antibiotic resistance, which poses a significant threat to human health. Probiotics have gained increasing popularity as an alternative to antibiotics, prompting the exploration of cost-effective fermentation substrates for large-scale production. MethodsThis work aimed to investigate the antimicrobial effect of probiotics lactic acid bacteria (LAB) against various pathogenic bacterial strains (e.g. S. Typhimurium O66, S. Typhimurium S251, E. coli O78:K80 and E. coli O157:H7). A total of 28 bacterial isolates were obtained from fermented food sources, in conjunction with 12 identified LAB strains, were screened for antimicrobial activity using microdilution broth method. The chosen probiotic strain, Lactobacillus acidophilus, was subsequently cultivated in a medium formulated with cane molasses to assess its suitability for probiotic production. Significant findingsThe results demonstrated that most LAB strains inhibited S. Typhimurium and E. coli by over 90 %. In the optimized cane molasses-based medium containing 16.02 % (v/v) molasses, 10 g/L (w/v) yeast extract with pH of 6.6, a cell dry weight (CDW) of 3.63 g/L of L. acidophilus was achieved. Therefore, cane molasses emerged as a promising alternative carbon source for LAB biomass production, offering the potential to reduce production costs while minimizing waste generation.

Callus formation and camphor aggregation in response to sorbitol stimulated osmotic stress in yarrow

Sorbitol is an important source of abiotic stress that is used to increase osmolality in cell cultures. It increases the antioxidant enzymes of defense catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) in the stress state of cells. Sorbitol plays an important role in stimulating these enzymes in cells and increasing phenylalanine ammonium lyase (PAL) activity. The aim of this study was to apply increasing doses of sorbitol elicitor to cell suspension cultures to determine the changes in cell number, viability, dry weight, and camphor content. In vitro plantlets were obtained from plant seeds and stem segments of these plants were used as explant source. Cell cultures were established after callus formation. Then, 0 (control), 5, 25, and 50 g L-1 sorbitol was dissolved in distilled water and cultured. Samples were taken three times in total, starting from day 1 to day 3. The content of camphor was detected by gas chromatography-mass spectrometry (GC-MS). Cell number, viability,dry weight, and camphor content increased significantly with increasing doses of sorbitol compared to sampling times. Compared to the initial culture, the amount of camphor increased by 40% at the 5 g L-1 dose, 82% at the 25 g L-1 dose, and 154% at the 50 g L-1 dose. In A. gypsicola cell cultures, increasing doses of sorbitol have clearly demonstrated the secondary metabolite accumulation and its positive effect on cell growth.

A holistic approach for process intensification of nicotinamide mononucleotide production via high cell density cultivation under exponential feeding strategy

Nicotinamide mononucleotide (NMN) subsists in all living organisms and has drawn tremendous attention as a nutraceutical and pharmaceutical product for several diseases such as Alzheimer’s, cancer, aging, and vascular dysfunction. Here, NMN was produced intracellularly in a high cell density bioreactor using an engineered Escherichiacoli strain via exponential feeding of co-substrates. Fed-batch culture via exponential feeding of co-substrate (glucose) and continuous feeding of substrate (nicotinamide) were performed using different cumulative nicotinamide concentrations. The highest concentration of 19.3 g/L NMN with a dry cell weight of 117 g/L was acquired from a cumulative nicotinamide concentration of 7.2 g/L with a conversion of 98 % from nicotinamide in 28 h. Further, liquid chromatography-mass spectrometry analysis validated the NMN production. This approach will be beneficial in achieving simultaneously low cost and ensuring high quality and quantity of NMN production.

Bioplastic (poly-3-hydroxybutyrate)-producing Massilia endophytica sp. nov., isolated from Cannabis sativa L. ‘Cheungsam’

A rod-shaped, motile, Gram-negative bacterial strain named DM-R-R2A-13T was isolated from the plant Cannabis sativa L. ‘Cheungsam’. The phylogenetic analysis of the 16S rRNA gene sequence revealed that strain DM-R-R2A-13T belongs to the family Oxalobacteraceae and is closely related to members of the genus Massilia, with Massilia flava (97.58% sequence similarity) and Massilia armeniaca (97.37% sequence similarity) being the closest members. The digital DNA-DNA hybridization (dDDH) values between strain DM-R-R2A-13T and Massilia flava CGMCC 1.10685T and Massilia armeniaca ZMN-3Twere 22.2% and 23.3%, while the average nucleotide identity (ANI) values were 78.85% and 79.63%, respectively. The DNA G+C content was measured to be 64.6 mol%. Moreover, the bacterium was found to contain polyhydroxyalkanoate (PHA) granules based on transmission electron microscopy, indicating its potential to produce bioplastic. Genome annotation revealed the presence of PHA synthase genes (phaC, phaR, phaP, and phaZ), and the biopolymer was identified as poly-3-hydroxybutyrate (PHB) based on nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) analyses. Using maltose as a carbon source, the strain produced PHB of up to 58.06% of its dry cell weight. Based on the phenotypic, chemotaxonomic, and phylogenetic characteristics, it has been determined that DM-R-R2A-13T represents a novel species belonging to the genus Massilia. As such, the name Massilia endophytica sp. nov. is proposed for this newly identified species. The type strain is DM-R-R2A-13T (= KCTC 92072T = GDMCC 1.2920T).

Production of poly (3-hydroxybutyrate) and extracellular polymeric substances from glycerol by the acidophile Acidiphilium cryptum.

Acidiphilium cryptum is an acidophilic, heterotrophic, and metallotolerant bacteria able to use dissolved oxygen or Fe(III) as an electron sink. The ability of this extremophile to accumulate poly(3-hydroxybutyrate) (PHB) and secrete extracellular polymeric substances (EPS) has also been reported. Hence, the aim of this work is to characterize the production of PHB and EPS by the wild strain DSM2389 using glycerol in shaken flasks and bioreactor. Results showed that maximum PHB accumulation (37-42% w/w) was obtained using glycerol concentrations of 9 and 15gL-1, where maximum dry cell weight titers reached 3.6 and 3.9gL-1, respectively. The culture in the bioreactor showed that PHB accumulation takes place under oxygen limitation, while the redox potential of the culture medium could be used for online monitoring of the PHB production. Recovered EPS was analyzed by Fourier-transform infrared spectroscopy and subjected to gas chromatography-mass spectrometry after cleavage and derivatization steps. These analyses showed the presence of sugars which were identified as mannose, rhamnose and glucose, in a proportion near to 3.2:2.3:1, respectively. Since glycerol had not been used in previous works, these findings suggest the potential of A. cryptum to produce biopolymers from this compound at a large scale with a low risk of microbial contamination due to the low pH of the fermentation process.

Development of a continuous fermentation process for the production of recombinant uricase enzyme by Pichia pastoris.

Recent studies in the biopharmaceutical industry have shown an increase in the productivity and production efficiency of recombinant proteins by continuous culture. In this research, a new upstream fermentation process was developed for the production of recombinant uricase in the methylotrophic yeast Pichia pastoris. Expression of recombinant protein in this system is under the control of the AOX1 promoter and therefore requires methanol as an inducing agent and carbon/energy source. Considering the biphasic growth characteristics of conventional fed-batch fermentation, physical separation of the growth and induction stages for better control of the continuous fermentation process resulted in higher dry-cell weight (DCW) and enhanced recombinant urate oxidase activity. The DCW and recombinant uricase activity enzyme for fed-batch fermentation were 79g/L and 6.8u/mL. During the continuous process, in the growth fermenter at a constant dilution rate of 0.025h-1 , DCW increased to 88.39g/L. In the induction fermenter, at methanol feeding rates of 30, 60, and 80mL/h, a recombinant uricase activity was 4.13, 7.2, and 0u/mL, respectively. The optimum methanol feeding regime in continuous fermentation resulted in a 4.5-fold improvement in productivity compared with fed-batch fermentation from 0.04u/mL/h (0.0017mg/mL/h) to 0.18u/mL/h (0.0078mg/mL/h).

Short Communication: The oleaginous Candida tropicalis isolated from mangrove soil in eastern Thailand and the fatty acid composition profile of its intracellular lipids

Abstract. Wongchamrearn S, Boontanom P, Ungwiwatkul S, Emnin N, Chantarasiri A. 2023. Short Communication: The oleaginous Candida tropicalis isolated from mangrove soil in eastern Thailand and the fatty acid composition profile of its intracellular lipids. Biodiversitas 24: 5088-5095. Oleaginous yeasts are microorganisms that can accumulate intracellular lipids at a rate of more than 20% of their cell dry weight. They are considered ideal microbes for a sustainable bioeconomy and a promising source for biotechnological applications. Thus, the exploration of efficient oleaginous yeasts from various environments is necessitated. At present, the number of oleaginous yeasts that have been discovered from mangrove environments remains scarce. Therefore, this study isolated and screened for lipid-accumulating yeast strains in mangrove soil samples collected from Rayong Province and Chonburi Province, Thailand. The intracellular lipids of isolated yeasts were extracted and quantitatively analyzed to evaluate the efficient oleaginous strains. Fifteen yeast strains were considered lipid-accumulating yeasts based on the Sudan IV staining method and lipid content determination, with intracellular lipid accumulation ranging from 5.71±1.89% (w/w) to 33.83±1.41% (w/w). The isolated yeast strain MJ13 was designated the most efficient oleaginous strain and subsequently genetically identified as Candida tropicalis. The fatty acid composition of its intracellular lipids was analyzed by gas chromatography, which consisted of five saturated fatty acids and five unsaturated fatty acids with 10-22 carbon atoms. The predominant fatty acids were palmitic (C16:0) and stearic (C18:0) acids. Some fatty acids essential to the human body and pharmacological sciences were detected, involving a-linolenic (C18:3n3) and cis-13,16-docosadienoic (C22:2) acids. This oleaginous yeast strain could be applied in lipid-related biofuel and high-value bioeconomy applications.

Production and characterization of a biodegradable polymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), using the type II methanotroph, Methylocystis sp. MJC1

The production of polyhydroxyalkanoates (PHAs) through the biological conversion of methane is a promising solution to address both methane emissions and plastic waste. Type II methanotrophs naturally accumulate a representative PHA, poly(3-hydroxybutyrate) (PHB), using methane as the sole carbon source. In this study, we aimed to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV copolymer) with improved properties compared with PHB, using the type II methanotroph, Methylocystis sp. MJC1. We optimized the pH, valerate concentration, and valerate supply time in a one-step cultivation process using a gas bioreactor to enhance PHBV copolymer production yield and the 3-hydroxyvalerate (3HV) molar fraction. Under the optimal conditions, the biomass reached 21.3 g DCW/L, and PHBV copolymer accumulation accounted for 41.9 % of the dried cell weight, with a 3HV molar fraction of 28.4 %. The physicochemical properties of the purified PHBV copolymer were characterized using NMR, FTIR, TGA, DSC, and GPC.

Reusing wastewater from Coffea arabica processing to produce single-cell protein using Candida sorboxylosa: Optimizing of culture conditions.

Coffee is a crop of significant socioeconomic importance, and the reuse of agri-food by-products and biowaste has great potential across several industries. Coffee wastewater (CWW) is a valuable resource containing essential nutrients that can be utilized by Candida sorboxylosa for single-cell protein (SCP) production. This utilization contributes to mitigating the negative impacts of agro-industrial waste. The optimization of culture conditions using the design of experiments (DoE) technique is crucial in understanding the environmental factors influencing metabolite production. In our study, the DoE technique was employed to analyze culture conditions, including room temperature, pH 8.4, agitation at 200 rpm, a headspace of 60% (v/v), and an inoculum of 0.75 DO600nm over 28-h period. This approach resulted in a remarkable SCP yield of 64.4% and dry cell weight (DCW) of 2.26 g/L. It is noteworthy that there is no literature reporting SCP production under alkaline pH conditions in yeast. Interestingly, our work demonstrated that an alkaline pH of 8.4 significantly influenced SCP production by C. sorboxylosa. The DoE technique proved to be an efficient statistical tool for optimizing culture conditions, offering several advantages, such as: (i) conducting cultures at room temperature to minimize unnecessary energy consumption; (ii) reducing the incubation time from 46 to 28 h, thereby enhancing overall productivity; (iii) achieving 1.7-fold increase in SCP yield compared to previous basal production levels.

Microbial production of zeaxanthin from algal biomass and waste glycerol using a newly isolated agarolytic marine bacterium Cellulophaga omnivescoria MSK1

With increasing interests in the biological conversion of waste resources into value-added chemicals and biocompounds, algal biomass has emerged as a promising renewable feedstock due to abundance, rapid growth, and sustainability. However, efficient bioconversion method is still being challenged due to the lack of suitable host strain capable of directly utilizing algal biomass and converting into desired products. In this study, a potent marine bacterium capable of producing zeaxanthin from algal biomass was investigated. The agarolytic bacterium, Cellulophaga omnivescoria MSK1 was isolated from coastal seawater. Through physiological and morphological analysis, it was confirmed that this bacterium degrade agarose into neoagarotetraose (NA4) and neoagarohexaose (NA6) and produces zeaxanthin using agarose as a carbon source. This bacterial strain demonstrated the ability to produce 2.23 ± 0.19 mg/L of zeaxanthin when provided with 0.2% agarose as a carbon source. By supplementing with glycerol, zeaxanthin production was further enhanced, reaching levels of 8.43 ± 0.31 mg/L, with a content of 6.77 ± 0.3 mg/g CDW (cell dry weight). These results suggest that an agarolytic Cellulophaga omnivescoria MSK1 strain has a great potential to be used as a platform microbial strain capable of producing zeaxanthin from algal biomass as a sustainable feedstock.

Bubble column photobioreactor (BCPR) for cultivating microalgae and microalgal consortium (Co-CC) with additional CO2 supply for enhancing biomass, lipid, and preferable fatty acids production

The present study has designed and developed a 5 L bubble column photobioreactor (BCPR) to investigate two microalgal strains Chlorella sp. S-01, Chlorella sp. S-02 and their consortium Co-CC (Chlorella sp. S-01 + Chlorella sp. S-02) at 0.03, 5, and 10% CO2 supply for biomass and lipid production. The dry cell weight of Chlorella sp. S-01, Chlorella sp. S-02 and Co-CC were, respectively about 1.41, 1.32, and 1.39 g/L on the 20th day without CO2 supply, while it was 1.76, 1.61, and 1.87 g/L, respectively at 10% CO2 supply and similarly, chlorophyll-a content was higher in 10% CO2 supplied condition over control. Interestingly, Co-CC grown at all the CO2 concentrations showed similar lipid content between 19.30 and 1F9.41%. As an integrated refinery approach, de-oiled biomass of Co-CC was subjected to carbohydrates and protein estimation and found that 46.2% and 30.80% in 10% CO2 supply condition in BCPR. Lipid extracted from the Co-CC grown under 0.03, 5, and 10% CO2 supply in 5L BCPR was converted to biodiesel, and the biodiesel yield was estimated to be 62.78%. Further, the fatty acid profile of Co-CC grown at 10% CO2 showed higher levels of C16:0, C16:1, C18:1, and monounsaturated fatty acids contents over other CO2 supplied conditions. Biodiesel of Co-CC showed favourable fuel properties such as density, higher heating value, oxidative stability, CFPP, viscosity, degree of unsaturation, saponification value, and cetane number, which were also in accordance with ASTM, and EN, biodiesel standards.

Efecto de la composición del medio de cultivo sobre el crecimiento y producción de biopoliésteres por la bacteria marina Saccharophagus degradans

The production of biomass and biopolyesters (polyhydroxyalkanoates) by the marine bacterium Saccharophagus degradans from: glucose, starch, glucosamine, and xylose were studied. The effect of yeast extract, trace elements, vitamins, and initial concentration of each carbon source on biomass production was evaluated. The addition of yeast extract, together with trace elements, increased the biomass production by 5-fold, obtaining the maximum values when using an initial substrate concentration of 20 g/L for: starch, 8.61; glucosamine, 7.06; and xylose, 4.47 (g dry cell weight/ L). From glucose at 40 g/L the maximum biomass production was 9.07 g/L. Next, the biopolymer production under nutrient-limiting conditions (by N, P, S and Mg) was investigated, as well as the ability of S. degradans to produce copolymers from precursors. The biopolyester produced in all cases was poly(3-hydroxybutyrate) (PHB). Different accumulation percentages (g PHB/100 g biomass) were achieved depending on the carbon source used: glucose, 27.72; starch, 18.11; glucosamine 3.33; there was not biopolymer accumulated from xylose. Finally, the PHB produced from each carbohydrate was characterized, presenting molecular weights between 53 and 58 KDa, and fusion temperatures between 164 and 174°C.