Airlift Fermenter Research Articles

Consolidated bioprocessing of lignocellulosic wastes in Northwest China for D-glucaric acid production by an artificial microbial consortium.

D-glucaric acid is a platform chemical of great importance and the consolidated bioprocessing (CBP) of lignocellulose by the microbial consortium of Trichoderma reesei C10 and Saccharomyces cerevisiae LGA-1C3S2 features prospects in biomanufacturing it. Here we compared some representative lignocelluloses in Northwest China including corn stover, wheat straw and switchgrass, and the leading pretreatments including steam explosion, subcritical water pretreatment, sodium hydroxide pretreatment, aqueous ammonia pretreatment, lime pretreatment, and diluted sulfuric acid pretreatment. It was found that sodium hydroxide pretreated switchgrass (SHPSG) was the best substrate for D-glucaric acid production, resulting in the highest D-glucaric acid titers, 11.69 ± 0.73g/L in shake flask and 15.71 ± 0.80g/L in 10L airlift fermenter, respectively. To the best of our knowledge, this is the highest D-glucaric acid production titer from lignocellulosic biomass. This work offers a paradigm of producing low-cost D-glucaric acid for low-carbon polyethylene 2,5-furandicarboxylate (PEF) and a reference on developing biorefinery in Northwest China.

Fumaric acid production from fermented oil palm empty fruit bunches using fungal isolate K20: a comparison between free and immobilized cells.

This study investigated the potential of using steam-exploded oil palm empty fruit bunches (EFB) as a renewable feedstock for producing fumaric acid (FA), a food additive widely used for flavor and preservation, through a separate hydrolysis and fermentation process using the fungal isolate K20. The efficiency of FA production by free and immobilized cells was compared. The maximum FA concentration (3.25 g/L), with 0.034 g/L/h productivity, was observed after incubation with the free cells for 96 h. Furthermore, the production was scaled up in a 3-L air-lift fermenter using oil palm EFB-derived glucose as the substrate. The FA concentration, yield, and productivity from 100 g/L initial oil palm EFB-derived glucose were 44 g/L, 0.39 g/g, and 0.41 g/L/h, respectively. The potential for scaling up the fermentation process indicates favorable results, which could have significant implications for industrial applications.

P3HB from CH4 using methanotrophs: aspects of bioreactor, fermentation process and modelling for cost-effective biopolymer production.

P3HB (poly-β-hydroxybutyrate), an energy-storage compound of several microorganisms, can be used as bioplastics material. P3HB is completely biodegradable under aerobic and aerobic conditions, also in the marine environment. The intracellular agglomeration of P3HB was examined employing a methanotrophic consortium. Supplanting fossil, non-degradable polymers by P3HB can significantly reduce the environmental impact of plastics. Utilizing inexpensive carbon sources like CH4 (natural gas, biogas) is a fundamental methodology to make P3HB production less costly, and to avoid the use of primary agricultural products such as sugar or starch. Biomass growth in polyhydroxyalkanoates (PHA) in general and in Poly (3-hydroxybutyrate) manufacture in specific could be a foremost point, so here the authors focus on natural gas as a proper carbon source and on the selection of bioreactors to produceP3HB, and in future further PHA, from that substrate. CH4 can also be obtained from biomass, e.g., biogas, syngas methanation or power-to-gas (synthetic natural gas, SNG). Simulation software can be utilized for examination, optimizing and scale-up of the process as shown in this paper. The fermentation systems continuously stirred tank reactor (CSTR), forced-liquid vertical loop bioreactor (VTLB), forced-liquid horizontal tubular loop bioreactor (HTLB), airlift (AL) fermenter and bubble column (BC) fermenter were compared for their methane conversion, kLa value, productivity, advantages and disadvantages. Methane is compared to methanol and other feedstocks. It was discovered that under optimum processing circumstances and using Methylocystis hirsuta, the cells accumulated 51.6% cell dry mass of P3HB in the VTLB setup.

Effect of pH and Different Fermentation Time Intervals on the Production of Single Cell Proteins (SCPs) from Potato Peels

Dried cells of microorganisms such as fungi, algae, and bacteria, known as Single-Cell Proteins (SCPs), are utilized as a source of protein supplements in animal feed or human food. These SCPs can be produced through the use of low-cost feedstocks and waste materials as sources of carbon and energy, which can be converted into biomass and concentrated proteins. Objective: To optimize the yield and growth of dry cell biomass through the manipulation of fermentation conditions. Methods: A batch fermentation process was used to produce dry cell biomass from a microorganism. Different pH values, fermentation times, and reactor configurations were tested, and the resulting biomass was analyzed for its protein content. Results: The maximum yield of dry cell biomass was achieved at pH 4.5, with a yield of 1.951 g/100 ml. The maximum dry biomass was achieved after 72 hours of fermentation, with a yield of 2.824 g/100 ml. The maximum yield of dry biomass was achieved with an Airlift fermenter at an aeration rate of 1.0 vvm and a temperature of 35°C for 72 hours, resulting in a yield of 5.452 g/L. The protein content of the dried cell biomass was found to be in the range of 45-55%. Conclusions: This study demonstrates that the yield and growth of dry cell biomass can be optimized by controlling the fermentation conditions, specifically pH, fermentation time, and reactor configuration. These findings may have implications for the industrial-scale production of dry cell biomass, as they offer insight into how to maximize yield and protein content.

Direct consolidated bioprocessing for d-glucaric acid production from lignocellulose under subcritical water pretreatment

d-glucaric acid production from lignocellulose is a valuable research field, but meets the same challenge as other biorefinery processes that prevents it from commercialization, high production costs. The very path to tackle this is to increase the titer, rate and yield (TRY) of d-glucaric acid production and simplify the process, on which this study focused. Herein we used a novel, clean and environmentally friendly pretreatment, subcritical water pretreatment (SCWP), based on which we compared consolidated bioprocessing (CBP) by the microbial consortium composed of Trichoderma reesei C10 and Saccharomyces cerevisiae LGA-1C3S2 with separated hydrolysis and fermentation (SHF). CBP was found to be advantageous over SHF because of its comparable yield, much more simplified bioprocess and bigger space for cost reduction. Then CBP was upgraded to direct consolidated bioprocessing (dCBP) by adapting the microbial consortium in the raw liquors of SCWP containing inhibitors and toxic chemicals. As a result, more integrated biorefinery processes from corn stover (CS), wheat straw (WS), rice straw (RS) and switchgrass (SG) to d-glucaric acid under SCWP were developed and scaled up from shake flasks to 10 L fermenters, stirred and airlift. The TRYs of d-glucaric acid were improved significantly. The airlift fermenter was preferable for the dCBPs, producing the highest concentrations of d-glucaric acid, which were 10.03 g/L from subcritical water pretreated CS (SWCPCS), 9.53 g/L from SWCPWS, 8.87 g/L from SWCPRS and 10.66 g/L from SWCPSG respectively. Subsequently, the dCBPs were coupled with the downstream separation to establish a closed-circuit circulation and 30 rounds was run successfully. The highly integrated process from lignocellulose to d-glucaric acid with the smallest number of single unit operations was obtained and reported for the first time, providing an important design for biorefinery. This work is of great significance for biomanufacturing d-glucaric acid and other bio-based chemicals.

Degradation of Poly(Butylene Succinate) and Poly(Butylene Succinate)/Poly(Lactide) Blends using Serine Protease Produced from Laceyella sacchari LP175

The thermophilic filamentous bacterium Laceyella sacchari LP175 was cultivated in a 10.0 L airlift fermenter to produce serine protease at 50 °C. Maximal serine protease activity at 1,123.32 ± 15.8 U/mL was obtained for cultivation at 0.6 vvm aeration rate for 36 h. The crude enzyme was applied for degradation of poly (butylene succinate) (PBS), and poly (butylene succinate)/poly(lactide) blend (PBS/PLA) powders at 50 °C for 48 h with different substrates and enzyme concentrations. Results showed that serine protease produced from L. sacchari LP175 degraded PBS and PBS/PLA at 46.5 ± 2.05 and 49.8 ± 1.45 %, respectively, at an initial substrate concentration of 100 g/L with 1,200 U/mL of serine protease activity. Percentage degradation of PBS and PBS/PLA was improved to 51.4 ± 1.06 and 56.9 ± 1.42 %, respectively, when upscaled in a 2.0 L stirrer fermenter with 200 rpm agitation rate. Degradation products evaluated by a scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) confirmed that serine protease produced from L. sacchari LP175 degraded both PBS and PBS/PLA polymers. Results showed that microbial enzyme technology could be used to degrade PBS and PBS/PLA blend polymers and reduce the accumulation of waste. HIGHLIGHTS Upscaled serine protease production was achieved in a 10 L airlift fermenter by sacchari LP175 using low-cost agricultural products as substrate The crude enzyme degraded PBS and PBS/PLA powders (100 g/L) at up to 51.4 and 56.9 %, respectively in a 2.0 L stirrer fermenter under optimal conditions Degradation products of PBS and PBS/PLA by crude enzyme produced from sacchari LP175 were characterized GRAPHICAL ABSTRACT

A one‐pot biosynthesis of an aerogel composite based on attapulgite clay/bacterial cellulose to remove Pb 2+ ion

A one‐pot biosynthesis of an aerogel composite based on attapulgite clay/bacterial cellulose to remove Pb ²⁺ ion

Professor Daniel I.C. Wang: A Legacy of Education, Innovation, Publication, and Leadership.

Professor Daniel I.C. Wang: A Legacy of Education, Innovation, Publication, and Leadership.

Utilization of Airlift Fermenters in the Mass Propagation of Pseudomonas and AureobasidiumSpecies for the Bioremediation of Crude Oil Polluted Aquatic Environments

This study involved the design and fabrication of airlift fermenters for the mass propagation of a consortium of three microorganisms (Pseudomonas aeruginosa, Pseudomonas fluorescence and Aureobasidium pullulans). The efficacy of the blend in the bioremediation of simulated crude oil polluted water systems environments was also tested with a view to generating more data on crude oil degrading microorganisms for bioremediation purposes. The organisms were separately grown on a gyratory shaker at 120 rpm and at 30 °C until notable growths were observed. Equal volume of the grown organisms (500 ml) of mixed culture was used as inoculum for the 4.5 L of medium in the 7 L airlift fermenter. Thereafter, this was transferred into the 45 litres medium in the 70 L fermenter until significant growth was observed at room temperature. Culture broths were withdrawn at intervals for the determination of biomass and residual hydrocarbon concentrations. The product from the 70 L fermenter was introduced into simulated polluted water systems from which samples were withdrawn weekly. Analyses for residual hydrocarbon contents were carried out using appropriate analytical techniques. The results showed that 78.5% hydrocarbon removal was observed in the 7 L fermenter after 72 h, while that of the 70 L fermenter was 97.8% after 180 h of fermentation. Polluted water sample treated with the microbes experienced 96.4% removal after 10 weeks of treatment. It was observed further that the application of NPK fertilizer biostimulant aided microbial activities in the removal of petroleum hydrocarbons than urea, cow dung and poultry droppings. The study has demonstrated that effective bioremediation of crude oil polluted water systems could be achieved through the application of biostimulants with mass propagated crude oil degrading organisms using airlift fermenter systems.
 Keywords: Pseudomonas aeruginosa; Pseudomonas fluorescence; Aureobasidium pullulans; Airlift fermenter; Bioremediation; Biostimulation; Bioaugmentation.

Diversity of Essential oils in Sop Cop Nature Reserve in Sơn La province

According the results of the plant species for essential oil in Sop Cop Nature Reserve Area have identified 228 species, 158 genus of 66 families belong Pinophyta and Magnoliophyta. The diversity of essential oils plants fully expressed in 5 life forms with the spectrum of life forms is: SB = 59,65Ph + 13,59 Th + 11,40Cr + 7,89 Ch + 7,44Hm. In addition to the value for essential oils, the species also give other uses such as medicine with 228 species, edible with 64 species, timber with 62 species, making wine yeast with 27 species, spices with 25 species, making bonsai 9 species, making flavor 5 species, 3 species of oil, and lowest with 2 species having poisonous. We have been identified 16 species of plants (accounting for 7.02%) as being endangered in Vietnam Red Book (2007) and 1 species in red list of IUCN (2017). These are species with a small number of individuals that need to have policies for conservation and development
 Keywords
 Essential oil plats, life form, plants, Sop Cop nature reserve.
 References
 [1] FAO/WHO, Guidelines for the Evaluation of Probiotics in Food, Joint FAO/WHO Working Group Report on Drafting Guidelines for the Evaluation of Probiotics in Food London, Ontario, Canada, April 30 and May 1, 2002.[2] J. Park, M.H. Floch, Prebiotics, probiotics, and dietary fiber in gastrointestinal disease, Gastroenterology Clinics of North America, 36 (2007) 47-63. https://doi.org/10.1016/j.gtc.2007. 03.001. [3] F. Mansour-Ghanaei, N. Dehbashi, K. Yazdanparast, A Shafaghi, Efficacy of Saccharomyces boulardii with antibiotics in acute amoebiasis, World Journal of Gastroenterology, 9(2003)1832-1833. https:// dx.doi.org/10.3748/ wjg.v9.i8.1832.[4] I. Castagliuolo, M.F. Riegler, L. Valenick, J.T. LaMont, C. Pothoulakis, Saccharomyces boulardii protease inhibits the effects of Clostridium difficile toxins A and B in human colonic mucosa, Infection and Immunity, 67, 1(1999)302-307. [5] A. Qamar, S. Aboudola, M. Warny, P. Michetti, C. Pothoulakis, J.T. LaMont, C.P. Kelly, Saccharomyces boulardii stimulates intestinal immunoglobulin A immune response to Clostridium difficile toxin A in mice, Infection and Immunity, 69 (2001) 2762-2765. https:// doi.org/10.1128/IAI.69.4.2762-2765.2001.[6] T.S. Chin, N.Z. Othman, R. A. Malek, N. Elmarzugi, O. M. Leng, S. Ramli, N. F. Musa, R. Aziz and H. El Enshasy, Bioprocess optimization for biomass production of probiotics yeast Saccharomyces boulardii in semi-industrial scale, Journal of Chemical and Pharmaceutical Research, 7, 3(2015)122-132. [7] D.T.N. Diep, P. George, E. Gorczyca, S. Kasapis, Studies on the viability of Saccharomyces boulardii within microcapsules in relation to the thermomechanical properties of wheyprotein. Food Hydrocolloids, 42 (2014) 232-238. https:// doi.org/10.1016/j.foodhyd.2013.07.024.[8] G.L. Miller, Use of dinitrosalicylic acid reagent for determination of reducing sugar. Analytical Chemistry, 31 (1959) 426-428 https://doi.org/ 10.1021/ac60147a030.[9] H. A. El-Enshasy and A. A. El-Shereef, Optimization of high cell density cultivation of (Probiotic/Biotherapeutic) yeast Saccharomyces boulardii adapted to dryness stress, Deutsche Lebensmittel-Rundschau 104,93(2008)89-394.[10] K. Rajkowska, A. K.-S. Bska and A. Rygala, Probiotic activity of Saccharomyces cerevisiae var.boulardii against human pathogens, Food Technology and Biotechnology, 50, 2 (2012) 230–236. [11] R. Zbinden, E.E. Gonczi, M. Altwegg, Inhibition of Saccharomyces boulardii (nom. inval.) on cell invasion of Salmonella typhimurium and Yersinia enterocolitica, Microbial Ecology in Health and Disease, 11(1999)158–162. https://doi.org/10. 1080/089106099435736.[12] D. Czerucka, T. Piche, P. Rampal, Review article: Yeasts as probiotics – Saccharomyces boulardii, Alimentary Pharmacology Therapeutics, 26(2007)767–778. https://doi.org/10.1111/j.1365 -2036.2007.03442.x.[13] L.V. Mc Farland, P. Bernacoscani, Saccharomyces boulardii. A Review of an Innovative Biotherapeutic Agent, Microbial Ecology in Health and Disease, 6(1993)157-171. https://doi. org/10.3109/08910609309141323.[14] K. Rajkowska and A. Kunicka-Styczynska, Probiotic properties of yeasts isolated from chicken feces and kefirs, Polish Journal of Microbiology, 59,4(2010) 257-263.[15] J.L.R. Fietto R.S. Araujo and F.N. Valadao, Molecular and physiological comparisons between Saccharomy cescerevisiae and Saccharomyces boulardii, Canadian Journal of Microbiology, 50 (2004) 615–621. https://doi. org/10.1139/w04-050.[16] J.L. Muller, K.L. Protti, M.S. Machado, L.L.V. Lacerda, T.M.B. Bresolin, P.S. Podlech, Comparison of Saccharomyces boulardii growth in an air-lift fermentor and in a shaker, Ciência e Tecnologia de Alimentos, 27,4(2007)688-693. http://dx.doi.org/10.1590/S0101-206120070004 00003.
 

Culture Condition for High Biomass Production of Probiotic Yeast Saccharomyces Boulardii SB2 in Shake Flask and 30 Littre Scale

Probiotic properties in vitroof the Saccharomyces boulardii SB2 yeast, was isolated from fruit at Cuc Phuong National Park were evaluated based on biological characteristics and tolerance in simulated intestinal conditions. In the present work, studies were carried out to improve cell growth kinetics to produce cell mass of this biotherapeutic yeast in shake flaskand 30-L bioreactor levels. In case of shake flask, the highest biomass was obtained under the culture conditions as YM medium, at 37oC, pH 6, inoculum concentration of 5 %, with shaking for 32 h; the best sources of carbon and nitrogen were found to be glucose and mixture of peptone, yeast extract, malt extract; cell dry weight and cell density reached 2.43 g L-1 and 109 CFU/ml repetitively. During 30-L bioreactor cultivation, the maximal cell mass in agitation speed of 200 rpm, aeration rate of 1.2 v v-1 min-1; at 32 h of incubation, was 3.58 g L-1 in pH controlled culture and 3.08 g L-1 in uncontrolled pH. This is considered as the first step for cell mass production of this probiotic yeast in industrial scale
 Keywords:
 Saccharomyces boulardii SB2, probiotic, biomass, shake flask, 30-L bioreactor.
 References
 [1] FAO/WHO, Guidelines for the Evaluation of Probiotics in Food, Joint FAO/WHO Working Group Report on Drafting Guidelines for the Evaluation of Probiotics in Food London, Ontario, Canada, April 30 and May 1, 2002.[2] J. Park, M.H. Floch, Prebiotics, probiotics, and dietary fiber in gastrointestinal disease, Gastroenterology Clinics of North America, 36 (2007) 47-63. https://doi.org/10.1016/j.gtc.2007. 03.001. [3] F. Mansour-Ghanaei, N. Dehbashi, K. Yazdanparast, A Shafaghi, Efficacy of Saccharomyces boulardii with antibiotics in acute amoebiasis, World Journal of Gastroenterology, 9(2003)1832-1833. https:// dx.doi.org/10.3748/ wjg.v9.i8.1832.[4] I. Castagliuolo, M.F. Riegler, L. Valenick, J.T. LaMont, C. Pothoulakis, Saccharomyces boulardii protease inhibits the effects of Clostridium difficile toxins A and B in human colonic mucosa, Infection and Immunity, 67, 1(1999)302-307. [5] A. Qamar, S. Aboudola, M. Warny, P. Michetti, C. Pothoulakis, J.T. LaMont, C.P. Kelly, Saccharomyces boulardii stimulates intestinal immunoglobulin A immune response to Clostridium difficile toxin A in mice, Infection and Immunity, 69 (2001) 2762-2765. https:// doi.org/10.1128/IAI.69.4.2762-2765.2001.[6] T.S. Chin, N.Z. Othman, R. A. Malek, N. Elmarzugi, O. M. Leng, S. Ramli, N. F. Musa, R. Aziz and H. El Enshasy, Bioprocess optimization for biomass production of probiotics yeast Saccharomyces boulardii in semi-industrial scale, Journal of Chemical and Pharmaceutical Research, 7, 3(2015)122-132. [7] D.T.N. Diep, P. George, E. Gorczyca, S. Kasapis, Studies on the viability of Saccharomyces boulardii within microcapsules in relation to the thermomechanical properties of wheyprotein. Food Hydrocolloids, 42 (2014) 232-238. https:// doi.org/10.1016/j.foodhyd.2013.07.024.[8] G.L. Miller, Use of dinitrosalicylic acid reagent for determination of reducing sugar. Analytical Chemistry, 31 (1959) 426-428 https://doi.org/ 10.1021/ac60147a030.[9] H. A. El-Enshasy and A. A. El-Shereef, Optimization of high cell density cultivation of (Probiotic/Biotherapeutic) yeast Saccharomyces boulardii adapted to dryness stress, Deutsche Lebensmittel-Rundschau 104,93(2008)89-394.[10] K. Rajkowska, A. K.-S. Bska and A. Rygala, Probiotic activity of Saccharomyces cerevisiae var.boulardii against human pathogens, Food Technology and Biotechnology, 50, 2 (2012) 230–236. [11] R. Zbinden, E.E. Gonczi, M. Altwegg, Inhibition of Saccharomyces boulardii (nom. inval.) on cell invasion of Salmonella typhimurium and Yersinia enterocolitica, Microbial Ecology in Health and Disease, 11(1999)158–162. https://doi.org/10. 1080/089106099435736.[12] D. Czerucka, T. Piche, P. Rampal, Review article: Yeasts as probiotics – Saccharomyces boulardii, Alimentary Pharmacology Therapeutics, 26(2007)767–778. https://doi.org/10.1111/j.1365 -2036.2007.03442.x.[13] L.V. Mc Farland, P. Bernacoscani, Saccharomyces boulardii. A Review of an Innovative Biotherapeutic Agent, Microbial Ecology in Health and Disease, 6(1993)157-171. https://doi. org/10.3109/08910609309141323.[14] K. Rajkowska and A. Kunicka-Styczynska, Probiotic properties of yeasts isolated from chicken feces and kefirs, Polish Journal of Microbiology, 59,4(2010) 257-263.[15] J.L.R. Fietto R.S. Araujo and F.N. Valadao, Molecular and physiological comparisons between Saccharomy cescerevisiae and Saccharomyces boulardii, Canadian Journal of Microbiology, 50 (2004) 615–621. https://doi. org/10.1139/w04-050.[16] J.L. Muller, K.L. Protti, M.S. Machado, L.L.V. Lacerda, T.M.B. Bresolin, P.S. Podlech, Comparison of Saccharomyces boulardii growth in an air-lift fermentor and in a shaker, Ciência e Tecnologia de Alimentos, 27,4(2007)688-693. http://dx.doi.org/10.1590/S0101-206120070004 00003.
 
 
 

Utilization of Airlift Fermenters in the Mass Propagation of Pseudomonas and AureobasidiumSpecies for the Bioremediation of Crude Oil Polluted Aquatic Environments

This study involved the design and fabrication of airlift fermenters for the mass propagation of a consortium of three microorganisms (Pseudomonas aeruginosa, Pseudomonas fluorescence and Aureobasidium pullulans). The efficacy of the blend in the bioremediation of simulated crude oil polluted water systems environments was also tested with a view to generating more data on crude oil degrading microorganisms for bioremediation purposes. The organisms were separately grown on a gyratory shaker at 120 rpm and at 30 °C until notable growths were observed. Equal volume of the grown organisms (500 ml) of mixed culture was used as inoculum for the 4.5 L of medium in the 7 L airlift fermenter. Thereafter, this was transferred into the 45 litres medium in the 70 L fermenter until significant growth was observed at room temperature. Culture broths were withdrawn at intervals for the determination of biomass and residual hydrocarbon concentrations. The product from the 70 L fermenter was introduced into simulated polluted water systems from which samples were withdrawn weekly. Analyses for residual hydrocarbon contents were carried out using appropriate analytical techniques. The results showed that 78.5% hydrocarbon removal was observed in the 7 L fermenter after 72 h, while that of the 70 L fermenter was 97.8% after 180 h of fermentation. Polluted water sample treated with the microbes experienced 96.4% removal after 10 weeks of treatment. It was observed further that the application of NPK fertilizer biostimulant aided microbial activities in the removal of petroleum hydrocarbons than urea, cow dung and poultry droppings. The study has demonstrated that effective bioremediation of crude oil polluted water systems could be achieved through the application of biostimulants with mass propagated crude oil degrading organisms using airlift fermenter systems. Keywords: Pseudomonas aeruginosa; Pseudomonas fluorescence; Aureobasidium pullulans; Airlift fermenter; Bioremediation; Biostimulation; Bioaugmentation.

Combining engineering strategies and fermentation technology to enhance docosahexaenoic acid (DHA) production from an indigenous Thraustochytrium sp. BM2 strain

The DHA productivity of Thraustochytrium sp. BM2 was improved by optimizing the bioreactor operation conditions. The effects of agitation rate and aeration rate on the microalgal growth and DHA production were first studied in 5-L stirred-tank fermenter. The results showed that 100 rpm agitation and 1.2 vvm aeration (i.e., kLa = 27 ± 1.1 h−1) achieved the highest biomass (4590 mg/L/d) and DHA (379 mg/L/d) productivities. Next, using an optimal glucose concentration (60 g/L) led to the highest biomass (5580 mg/L/d) and DHA (457 mg/L/d) productivities. The cellular DHA content decreased when increasing the agitation rate, probably due to the sensitivity of this strain to the shear stress. The effect of pneumatic and mechanical agitation under the same kLa was studied with two different types of fermenters (stirred-tank and air-lift) and cultivation in air-lift fermenter resulted in better biomass production (27.57 g/L), cellular DHA content (13.1%) and DHA productivity (610 mg/L/d).

Enhancement of poly(L-lactide)-degrading enzyme production by Laceyella sacchari LP175 using agricultural crops as substrates and its degradation of poly(L-lactide) polymer

Optimization of the medium for poly(L-lactide) (PLLA)-degrading enzyme production in shake flask experiments was investigated using agricultural products as substrates. Cassava chips and soybean meal were the best carbon and nitrogen sources, respectively, as determined by the one-factor-at-a-time method. Enzyme production was significantly enhanced by the addition of phosphates, but was suppressed by the addition of ammonium salt. The maximum enzyme production, 65.5 U/mL, was obtained from the optimized medium consisting of 4.64 g/L cassava chips, 1.53 g/L soybean meal and 0.31 g/L PLLA powder using central composite design in the basal medium. The optimal physical factors in 3 L airlift fermenter were 50 °C, pH 7.0 and 0.5 vvm aeration rate for 18 h, yielded 94.4 U/mL. The crude enzyme was shown to be able to hydrolyze PLLA powder (91%) at 50 °C in 72 h which showed high efficiency for recycling of PLLA polymer and reducing the global environmental problem.

Production of raw starch degrading enzyme by the thermophilic filamentous bacterium Laceyella sacchari LP175 and its application for ethanol production from dried cassava chips

Physical factors that enhanced the production of raw starch degrading enzyme by a thermophilic filamentous bacterium, Laceyella sacchari LP175 in a 3 L airlift fermenter, were optimized at a pH of 6.5, a temperature of 45°C, and an aeration rate of 0.5 vvm using a central composite design. This yielded 278 U/mL, at 36 h cultivation, an increase in enzyme production and productivity of 1.53‐ and 2.04‐fold, respectively, as compared with a shaking flask cultivation. Raw starch degrading enzyme produced by L. sacchari LP175 with commercial glucoamylase synergistically enhanced the hydrolysis of 300 g/L dried cassava chips (71% starch content) to 157 g/L reducing sugars, equivalent to 66.3% hydrolysis at pH 6.5 and 50°C for 12 h. The comparative study on bioethanol production in a non‐sterile system from dried cassava chip by three different processes; the maximum production, 90.9 g/L (88% theoretical yield), was obtained by modified simultaneous saccharification and fermentation at 50°C for 6 h and subsequent fermentation by the thermotolerant Kluyveromyces marxianus DMKU‐KS07 at 42°C within 18 h with the highest productivity of 3.79 g/L/h. The other processes tested – separate hydrolysis and fermentation and simultaneous saccharification and fermentation – yielded 83 and 51.6 g/L of ethanol, respectively.

Poly(3-hydroxybutyrate) (PHB) production from CO2: Model development and process optimization

The biosynthesis of poly(3-hydroxybutyrate) (PHB) directly from carbon dioxide (CO2), is a sustainable alternative for non-renewable, petroleum-based polymer production. The conversion of CO2 implies a reduction of greenhouse gas emissions. Hydrogen oxidizing bacteria such as Cupriavidus necator have the ability to store PHB using CO2 as a carbon source, i.e., through an autotrophic conversion. In this study, a mathematical model based on mass balances was set up to describe autotrophic PHB production. The model takes into account the stoichiometry and kinetics of biomass growth and PHB formation as well as physical transfer from the gas phase to the liquid fermentation broth. The developed model was calibrated and validated based on independent experimental datasets from literature, obtained for C. necator. The obtained simulation results accurately described the dynamics of autotrophic biomass growth and PHB production. The effect of oxygen (O2) and/or nitrogen stress conditions, as well as of the gas mixture composition in terms of O2 and hydrogen (H2) was investigated through scenario analysis. As major outcome, a higher maximum PHB concentration was obtained under oxygen stress conditions compared to nitrogen stress conditions. At high O2 fractions in the gas mixture, which would result in H2 limitation before O2 limitation, PHB production can be increased by applying nitrogen stress. The effect of the reactor type was assessed through comparing a continuous stirred tank reactor (CSTR) with an air-lift fermentor. The developed model forms the basis for future design with minimum experimentation of suitable control strategy aiming at a high PHB production.

Efek Sumber Karbon Berbeda terhadap Produksi â-Glukan oleh Saccharomyces Cerevisiae pada Fermentor Air Lift

The need of â-glucan is increasing in food, medicine and cosmetic industry, because it becomes anticancer,antitumor and antiaging, increases immunosystem, and decreases cholesterol content in blood. The cell walls ofS. cerevisiae contain 80-90% polysaccharides that posses â-glucan. This research was aimed to obtain appropriatecarbon sources to increase the production of â-glucan. The carbon sources used were glucose, glucose commercial,sucrose and molases. The fermentation process was done by using air lift fermentor. The steps of fermentatonincluded regeneration of S. cerevisiae strain, preculture, fermentor preparation and running fermentor for 84hours. Sampling of S. cerevisiae culture was determined the cell growth by optical density (OD) usingspectrophotometer UV/VIS at ë 550 nm. The protein content was determined by Lowry method at ë 755 nm and thetotal glucose was measured by phenol sulphate method at ë 490 nm. The measurement result of cell growthshowed that the high intensity of S. cerevisiae in medium contain molases, but it did not show significant effectwhen compare to other carbon sources. The protein and carbohydrate contain in medium tended to decrease. Theresult of â-glucan on glucose, sucrose, glucose commercial and molases were 933,3, 1100, 1000, and966,7 mg/l. It can be concluded that sucrose and glucose commercial can replace the glucose to produce of â-glucan, because they are cheaper and easier to get. Beside that, molases can be used as an alternative carbonsource because it can produce of â-glucan as well as glucose.

Poly(L-Lactide)-Degrading Enzyme Production by Actinomadura keratinilytica T16-1 in 3 L Airlift Bioreactor and Its Degradation Ability for Biological Recycle

The optimal physical factors affecting enzyme production in an airlift fermenter have not been studied so far. Therefore, the physical parameters such as aeration rate, pH, and temperature affecting PLA-degrading enzyme production by Actinomadura keratinilytica strain T16-1 in a 3 l airlift fermenter were investigated. The response surface methodology (RSM) was used to optimize PLA-degrading enzyme production by implementing the central composite design. The optimal conditions for higher production of PLA-degrading enzyme were aeration rate of 0.43 vvm, pH of 6.85, and temperature at 46° C. Under these conditions, the model predicted a PLA-degrading activity of 254 U/ml. Verification of the optimization showed that PLA-degrading enzyme production of 257 U/ml was observed after 3 days cultivation under the optimal conditions in a 3 l airlift fermenter. The production under the optimized condition in the airlift fermenter was higher than un-optimized condition by 1.7 folds and 12 folds with un-optimized medium or condition in shake flasks. This is the first report on the optimization of environmental conditions for improvement of PLA-degrading enzyme production in a 3 l airlift fermenter by using a statistical analysis method. Moreover, the crude PLA-degrading enzyme could be adsorbed to the substrate and degraded PLA powder to produce lactic acid as degradation products. Therefore, this incident indicates that PLA-degrading enzyme produced by Actinomadura keratinilytica NBRC 104111 strain T16-1 has a potential to degrade PLA to lactic acid as a monomer and can be used for the recycle of PLA polymer.

Kinetic models of ribonucleic acid fermentation and continuous culture by Candida tropicalis no.121

During ribonucleic acid fermentation, the fermentative processes were researched at pH controlled at 4.0 and under natural conditions. Unstructured models in a 50-L airlift fermentor were established for batch RNA production at pH 4.0 using the Verhulst equation for microbial growth, the Luedeking-Piret equation for product formation and a Luedeking-Piret-like equation for substrate uptake. Parameters of the kinetic models were determined using origin 7.5. Based on the models estimated above, another batch fermentation experiment was conducted in a 300-L airlift fermentor, which demonstrated that the models could be useful for RNA production on an industrial scale. Additionally, continuous fermentation based on kinetic models was proposed to make full use of substrates and reduce the cost of waste water treatment. As a result, although the DCW and RNA concentration were 11.5 and 1.68gL(-1), which were lower than that of batch fermentation, the sugar utilization increased by 14.3%, while the waste water decreased by more than 90%.

Relation between Volumetric Mass Transfer Coefficient and Power Input per Unit Volume for Converging-Diverging Tube Airlift Fermenter

A conventional external loop uniform tube airlift fermenter (UT-ALF) was modified to improve its performance. The riser part was replaced by a converging- diverging tube. The newly developed reactor system is named a converging-diverging tube airlift fermenter (CDT–ALF). The modified bioreactor (CDT–ALF) provides a unique hydrodynamic characteristic. Empirical correlation was developed to determine KLa with respect to power input per unit volume. The modified system (CDT-ALF) shows 250% higher KLa compared to conventional one.