Sustainable carbon sources for microbial organic acid production with filamentous fungi

Dörsam, Stefan; Fesseler, Jana; Gorte, Olga; Hahn, Thomas; Syldatk, Christoph; Ochsenreither, Katrin

doi:10.1186/s13068-017-0930-x

Cited by 64 publications

(38 citation statements)

References 46 publications

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“…Since cellulase is an inducible enzyme, the medium for cellulose production in fermentation usually contains cellulose-rich substrates for a carbon source (LEE et al, 2008;DORSAM et al 2017;. In this medium, different carbon sources were tested at different concentrations in order to study their effects on cellulase production under uniform conditions (incubation time, 24 h; rotation speed, 220 rpm; temperature, 37°C; seeded culture concentration, 1%).…”

Section: Resultsmentioning

confidence: 99%

Isolation and molecular identification of a cellulotic bacterium from muncipal waste and investigation of its cellulase production

Zamani¹,

Salehzadeh²,

Abdolhosseini³

2018

Biosci. J.

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Municipal waste is rich in lignocellulosic compounds which contain cellulose, lignin and hemicellulose. Microorganisms can break down such compounds and convert them into glucose and other carbohydrates. The current study was performed to isolate and identify cellulolytic bacteria in municipal waste. Municipal waste samples were collected and plated on Carboxymethyl cellulose (CMC) agar. Preliminary identification of the isolates was performed using standard biochemical assays. The activity of carboxymethyl cellulose (CMCase) was specified through measuring the release of reducing sugars from CMC. Different nitrogen sources at various concentrations and initial pH values were evaluated for their effect on enzyme production. Further the enzyme production was determined at different fermentation times. Molecular identification was then performed using bacterial 16s rRNA gene amplification and sequencing. A cellulolytic bacterium was isolated from municipal waste samples and identified based on morphological, physiological and biochemical characteristics along with 16S rRNA analysis. The isolated bacterium was identified as Bacillus subtilis (accession number: KU681044). Whose growth characteristics showed that its growth curve entered the logarithmic phase following 10-18 h with the stable growth phase ranging from 23 to 37 h. The optimal carbon source for fermentation was 1% rice hull, with the nitrogen source comprised of 2% peptone and yeast extract. The the minimum CMCase activity was observed at an initial medium pH of 4.0, while the maximum was observed at pH 7. The strain grew vigorously and the cellulase yield was high at 6-24 h fermentation time period. The isolated bacteria showed the degrading potential of cellulose which could be employed in local industrial process.

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Section: Resultsmentioning

confidence: 99%

Isolation and molecular identification of a cellulotic bacterium from muncipal waste and investigation of its cellulase production

Zamani¹,

Salehzadeh²,

Abdolhosseini³

2018

Biosci. J.

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“…The reactor was heated up to the reaction temperature of 180°C with a constant water flow. When the reaction temperature was reached, 0.05 mol/L sulfuric acid was introduced to the reactor and the hydrolyzate was constantly removed. The two‐step acid hydrolysis included a high concentration of hydrochloric acid (32% and 28%), HC fraction, and rice hulls (hydrolyzate c; Green Sugar AG) as described previously (Green Sugar AG, ). Steam explosion followed by enzymatic hydrolysis included CE/HC, miscanthus (hydrolyzate d), and wheat straw (hydrolyzate e) as described previously (Schläfle et al, ). For the organosolv process followed by enzymatic hydrolysis, CE fraction (hydrolyzate f), HC fraction (hydrolyzate g), and beech were used as described in Dörsam et al ().…”

Section: Methodsmentioning

confidence: 99%

“…• Steam explosion followed by enzymatic hydrolysis included CE/HC, miscanthus (hydrolyzate d), and wheat straw (hydrolyzate e) as described previously (Schläfle et al, 2017). • For the organosolv process followed by enzymatic hydrolysis, CE fraction (hydrolyzate f), HC fraction (hydrolyzate g), and beech were used as described in Dörsam et al (2017).…”

Section: Hydrolyzatesmentioning

confidence: 99%

Potential of biotechnological conversion of lignocellulose hydrolyzates by Pseudomonas putida KT2440 as a model organism for a bio‐based economy

et al. 2019

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Lignocellulose‐derived hydrolyzates typically display a high degree of variation depending on applied biomass source material as well as process conditions. Consequently, this typically results in variable composition such as different sugar concentrations as well as degree and the presence of inhibitors formed during hydrolysis. These key obstacles commonly limit its efficient use as a carbon source for biotechnological conversion. The gram‐negative soil bacterium Pseudomonas putida KT2440 is a promising candidate for a future lignocellulose‐based biotechnology process due to its robustness and versatile metabolism. Recently, P. putida KT2440_xylAB which was able to metabolize the hemicellulose (HC) sugars, xylose and arabinose, was developed and characterized. Building on this, the intent of the study was to evaluate different lignocellulose hydrolyzates as platform substrates for P. putida KT2440 as a model organism for a bio‐based economy. Firstly, hydrolyzates of different origins were evaluated as potential carbon sources by cultivation experiments and determination of cell growth and sugar consumption. Secondly, the content of major toxic substances in cellulose and HC hydrolyzates was determined and their inhibitory effect on bacterial growth was characterized. Thirdly, fed‐batch bioreactor cultivations with hydrolyzate as the carbon source were characterized and a diauxic‐like growth behavior with regard to different sugars was revealed. In this context, a feeding strategy to overcome the diauxic‐like growth behavior preventing accumulation of sugars is proposed and presented. Results obtained in this study represent a first step and proof‐of‐concept toward establishing lignocellulose hydrolyzates as platform substrates for a bio‐based economy.

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“…l ‐malate can also be used to treat hyperammonemia and liver dysfunction as a component of amino acid infusions (Battat, Peleg, Bercovitz, Rokem, & Goldberg, ). Recently, l ‐malate has been produced by natural or genetically engineered microbes, including Clostridium formicoaceticum (Dorn, Andreesen, & Gottschalk, ), Aspergillus flavus (Battat et al, ; Peleg, Stieglitz, & Goldberg, ), Saccharomyces cerevisiae (Nakayama et al, ; Schwartz & Radler, ; Zelle et al, ), Escherichia coli (Moon, Hong, & Kim, ; Zhang, Wang, Shanmugam, & Ingram, ), Rhizopus delemar (Dörsam et al, ; Li et al, ), and Ustilago trichophora (Zambanini et al, ). However, these producers have some shortcomings, such as aflatoxin accumulation, long fermentation time, and process unstability, which limit their application in industrial scale.…”

Section: Introductionmentioning

confidence: 99%

“…As a generally recognized as safe (GRAS) strain, Aspergillus oryzae has been widely used in food fermentation and is also an advantageous cell factory to produce l ‐malate (Brown et al, ; Dörsam et al, ; Knuf et al, ; Knuf et al, ). To verify the potential for l ‐malate production, A. oryzae NRRL3485 and NRRL3488 were compared, and A. oryzae NRRL3488 showed a higher final titer up to 30.27 g/L (Knuf et al, , ).…”

Section: Introductionmentioning

confidence: 99%

Morphology engineering of Aspergillus oryzae for l‐malate production

Chen

Zhou

Ding

et al. 2019

Biotech & Bioengineering

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Aspergillus oryzae is a competitive natural producer for organic acids, but its production capacity is closely correlated with a specific morphological type. Here, morphology engineering was used for tailoring A. oryzae morphology to enhance L-malate production. Specifically, correlation between A. oryzae morphology and L-malate fermentation was first conducted, and the optimal range of the total volume of pellets in a unit volume of fermentation broth (V value) for L-malate production was 120-130 mm 3 /ml. To achieve this range, A. oryzae morphology was improved by controlling the variation of operational parameters, such as agitation speed and aeration rate, and engineered by optimizing the expression of cell division cycle proteins such as tyrosine-protein phosphatase (CDC14), anaphase promoting complex/cyclosome activator protein (CDC20), and cell division control protein 45 (CDC45). By controlling the strength of CDC14 at a medium level, V value fell into the optimal range of V value and the final engineered strain A. oryzae CDC14 (3) produced up to 142.5 g/L L-malate in a 30-L fermenter. This strategy described here lays a good foundation for industrial production of L-malate in the future, and opens a window to develop filamentous fungi as cell factories for production of other chemicals. K E Y W O R D SAspergillus oryzae, L-malate, metabolic engineering, morphology engineering

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Sustainable carbon sources for microbial organic acid production with filamentous fungi

Cited by 64 publications

References 46 publications

Isolation and molecular identification of a cellulotic bacterium from muncipal waste and investigation of its cellulase production

Isolation and molecular identification of a cellulotic bacterium from muncipal waste and investigation of its cellulase production

Potential of biotechnological conversion of lignocellulose hydrolyzates by Pseudomonas putida KT2440 as a model organism for a bio‐based economy

Morphology engineering of Aspergillus oryzae for l‐malate production

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