An innovative integrated bioprocess system for bioethanol production from raw sugar beet cossettes (SBC) and arabitol from remaining exhausted sugar beet cossettes (ESBC) was studied. This integrated ...three-stage bioprocess system is an example of the biorefinery concept to maximise the use of raw SBC for the production of high value-added products such as sugar alcohols and bioethanol.
The first stage of the integrated bioprocess system was simultaneous sugar extraction from SBC and its alcoholic fermentation to produce bioethanol in an integrated bioreactor system (vertical column bioreactor and stirred tank bioreactor) containing a high-density suspension of yeast
(30 g/L). The second stage was the pretreatment of ESBC with dilute sulfuric acid to release fermentable sugars. The resulting liquid hydrolysate of ESBC was used in the third stage as a nutrient medium for arabitol production by non-
yeasts (
CBS 10155 and
CBS 11463).
The obtained results show that the efficiency of bioethanol production increased with increasing temperature and prolonged residence time in the integrated bioreactor system. The maximum bioethanol production efficiency (87.22 %) was observed at a time of 60 min and a temperature of 36 °C. Further increase in residence time (above 60 min) did not result in the significant increase of bioethanol production efficiency. Weak acid hydrolysis was used for ESBC pretreatment and the highest sugar yield was reached at 200 °C and residence time of 1 min. The inhibitors of the weak acid pretreatment were produced below bioprocess inhibition threshold. The use of the obtained liqiud phase of ESBC hydrolysate for the production of arabitol in the stirred tank bioreactor under constant aeration clearly showed that
CBS 10155 with 8.48 g/L of arabitol (
=0.603 g/g and bioprocess productivity of 0.176 g/(L
h)) is a better arabitol producer than
CBS 10155.
An innovative integrated bioprocess system for the production of bioethanol and arabitol was developed based on the biorefinery concept. This three-stage bioprocess system shows great potential for maximum use of SBC as a feedstock for bioethanol and arabitol production and it could be an example of a sustainable 'zero waste' production system.
Brewers' spent grains (BSG) are a by-product of the brewing industry that is mainly used as feedstock; otherwise, it has to be disposed according to regulations. Due to the high content of glucose ...and xylose, after pretreatment and hydrolysis, it can be used as a main carbohydrate source for cultivation of microorganisms for production of biofuels or biochemicals like 2,3-butanediol or lactate. 2,3-Butanediol has applications in the pharmaceutical or chemical industry as a precursor for varnishes and paints or in the food industry as an aroma compound. So far,
,
,
, and
are being used and investigated in different bioprocesses aimed at the production of 2,3-butanediol. The main drawback is bacterial pathogenicity which complicates all production steps in laboratory, pilot, and industrial scales. In our study, a gram-positive GRAS bacterium
DSM 742 was used for the production of 2,3-butanediol. Since this strain is very poorly described in literature, bacterium cultivation was performed in media with different glucose and/or xylose concentration ranges. The highest 2,3-butanediol concentration of 18.61 g l
was achieved in medium with 70 g l
of glucose during 40 h of fermentation. In contrast, during bacterium cultivation in xylose containing medium there was no significant 2,3-butanediol production. In the next stage, BSG hydrolysates were used for bacterial cultivation.
DSM 742 cultivated in the liquid phase of pretreated BSG produced very low 2,3-butanediol and ethanol concentrations. Therefore, this BSG hydrolysate has to be detoxified in order to remove bacterial growth inhibitors. After detoxification, bacterium cultivation resulted in 30 g l
of lactate, while production of 2,3-butanediol was negligible. The solid phase of pretreated BSG was also used for bacterium cultivation after its hydrolysis by commercial enzymes. In these cultivations,
DSM 742 produced 9.8 g l
of 2,3-butanediol and 3.93 g l
of ethanol. On the basis of the obtained results, it can be concluded that different experimental setups give the possibility of directing the metabolism of
DSM 742 toward the production of either 2,3-butanediol and ethanol or lactate.
Various fungal species can degrade lignocellulolytic materials with their enzyme cocktails composed of cellulolytic and lignolytic enzymes. In this work, seven fungal species (
DSM 2185,
CBS 372.70,
...CBS 663.74,
CBS 456.75,
JCM 2738,
f.sp.
JCM 9293, and
JCM 23107) and four nutrient media were used in the screening for effective lignocellulose degrading enzymes. From the seven tested fungi,
and
, along with nutrient medium 4, were selected as the best medium and producers of lignocellulolytic enzymes based on the determined xylanase (>4 U mg
) and glucanase activity (≈2 U mg
). Nutrient medium 4 supplemented with pretreated corn cobs was used in the production of lignocellulolytic enzymes by sequential solid-state and submerged cultivation of
,
, and a mixed culture of both strains.
showed 6 times higher exoglucanase activity (3.33 U mg
) after 5 days of cultivation in comparison with
(0.55 U mg
).
also showed 2 times more endoglucanase activity (0.33 U mg
). The mixed culture cultivation showed similar endo- and exoglucanase activities compared to
(0.35 U mg
; 7.84 U mg
). Maximum xylanase activity was achieved after 7 days of cultivation of
(≈16 U mg
), while
showed maximum activity after 9 days that was around 2 times lower compared to that of
The mixed culture achieved maximum xylanase activity after only 4 days, but the specific activity was similar to activities observed for
It can be concluded that both fungal strains can be used as producers of enzyme cocktails for the degradation of lignocellulose containing raw materials, and that corn cobs can be used as an inducer for enzyme production.
Fossil fuels are still major energy sources, but the search for renewable energy sources has been encouraged. Bioethanol has been recognized as an alternative to fossil fuels and nowadays it ...represents more than 90% of the global biofuel production. Bioethanol production from raw sugar beet cossettes as a semi-solid substrate was studied. The study was carried out in the horizontal rotating tubular bioreactor (HRTB) with
Saccharomyces cerevisiae
as a microbial production strain. The impact of different combinations of HRTB operational parameters such as, rotation speed (5–15 min
−1
), rotation type constant or interval (3–15 min h
−1
) and working volume (ratio
V
W
/
V
T
= 0.2–0.7) on the bioethanol production was examined. In this study, the highest bioprocess efficiency parameters (
Y
P
1
/
S
= 0.47 g g
−1
,
E
= 87.36% and Pr = 0.618 g L
−1
h
−1
) were observed at 0.20
V
W
/
V
T
, interval rotation of 12 min h
−1
and rotation speed of 15 min
−1
. It has to be pointed out that bioethanol production efficiency in the HRTB was on the similar level as observed by bioethanol production from the raw sugar beet juice. Naturally present microorganisms of sugar beet could have a significant impact on bioethanol production. Higher yeast inoculation rate could reduce contaminant activities and, consequently, the bioethanol production efficiency would be improved.
Alternative to the use of fossil fuels are biofuels (e.g., bioethanol, biodiesel and biogas), which are more environmentally friendly and which can be produced from different renewable resources. In ...this investigation, bioethanol production from raw sugar beet cossettes (semi-solid substrate) by yeast Saccharomyces cerevisiae in a horizontal rotating tubular bioreactor (HRTB) was studied. Obtained results show that HRTB rotation mode (constant or interval) and rotation speed have considerable impact on the efficiency of bioethanol production in the HRTB. The main goal of this research was to develop a non-structural mathematical model of bioethanol production from raw sugar beet cossettes in the HRTB. The established mathematical model of bioethanol production in the HRTB describes substrate utilization and product formation (glycerol, ethanol and acetate) and presumes negative impact of high substrate concentration on the working microorganism (substrate inhibition) by using Andrews inhibition kinetics. All simulations of bioethanol production in the HRTB were performed by using Berkeley Madonna software, version 8.3.14 (Berkeley Madonna, Berkeley, CA, USA). The established non-structural bioprocess model describes relatively well the bioethanol production from raw sugar beet cossettes in the HRTB.
In this investigation, the production of ethanol from the raw sugar beet juice and raw sugar beet cossettes has been studied. For ethanol production from the raw sugar beet juice, batch and fed-batch ...cultivation techniques in the stirred tank bioreactor were used, while batch ethanol production from the raw sugar beet cossettes was carried out in horizontal rotating tubular bioreactor (HRTB). In both cases, Saccharomyces cerevisiae was used as a production microorganism. During batch ethanol production from the raw sugar beet juice, ethanol yield was 59.89 g/L and production efficiency 78.8 %, and in fed-batch process the yield was 92.78 g/L and efficiency 93.4 %. At the same time, ethanol production in HRTB from the raw sugar beet cossettes with inoculum of 16.7 % V/m (raw sugar beet cossettes) resulted in the highest ethanol yield of 54.53 g/L and production efficiency of 79.5 %. The obtained results clearly show that both intermediates of sugar beet processing can be successfully used for ethanol production. Key words: ethanol, fermentation, raw sugar beet juice, raw sugar beet cossettes, stirred tank bioreactor, horizontal rotating tubular reactor (HRTB)
Glavni proizvod anaerobne digestije je bioplin, koji je obnovljivo gorivo, a sporedni proizvod ovog procesa je digestat, koji se koristi kao gnojivo bogato hranjivim tvarima. Dodatni pozitivni učinci ...anaerobne digestije su razgradnja organskog otpada te smanjenje neugodnih mirisa i koncentracije patogenih mikroorganizama. Bioplin se uglavnom koristi za proizvodnju električne energije i topline, a u nekim slučajevima se pročišćava da bi se dobio biometan koji se koristi u mreži prirodnog plina, kao gorivo za motore s unutarnjim sagorijevanjem ili kao polazna kemikalija za kemijsku industriju. Zbog svega navedenog, razvoj proizvodnje bioplina ima pozitivne društveno-ekonomske i ekološke učinke. Bioplin proizveden u Hrvatskoj većinom se koristi za proizvodnju električne i toplinske energije u kogeneracijskim postrojenjima. Iako su u Hrvatskoj dostupne različite obnovljive sirovine koje bi se mogle iskoristiti za proizvodnju bioplina, njihov je potencijal do sada bio nedovoljno iskorišten. Kao sirovine za proizvodnju bioplina u nas se pretežno koriste gnojovka i nusproizvodi poljoprivrede, klaonica i prehrambene industrije. Racionalnijim korištenjem zemljišta i razvojem prehrambene industrije mogla bi se povećati količina poljoprivrednih ostataka i nusproizvoda koji nastaju preradom hrane. Usmjeravanjem i poticanjem korištenja ovih nusproizvoda za anaerobnu digestiju može se stimulirati brži razvoj proizvodnje bioplina u Hrvatskoj. Pored mogućeg povećanja vlastite proizvodnje električne energije i goriva, radi se o ekološki povoljnoj tehnologiji koja ima pozitivan društveno-ekonomski učinak.
The main product of anaerobic digestion is biogas, which is a renewable fuel, and the by-product of this process is digestate, which is used as a nutrient-rich fertilizer. Additional positive effects of anaerobic digestion are the decomposition of organic waste and the reduction of unpleasant odors and the concentration of pathogenic microorganisms. Biogas is mainly used for the production of electricity and heat, and in some cases it is purified to obtain biomethane which is used in the natural gas network, as a fuel for internal combustion engines or as a starting chemical for the chemical industry. Due to all of the above, the development of biogas production has positive socio-economic and ecological effects. Biogas produced in Croatia is mostly used for the production of electricity and thermal energy at cogeneration plants. Although various renewable raw materials are available in Croatia that could be used for biogas production, their potential has been underutilized until now. Manure and by-products of agriculture, slaughterhouses and the food industry are mainly used as raw materials for the production of biogas in our country. More rational use of land and development of the food industry could increase the amount of agricultural residues and by-products resulting from food processing. Directing and encouraging the use of these by-products for biogas production can stimulate a faster development of biogas production in our Croatia. In addition to the possible increase in own production of electricity and fuel, it is an environmentally friendly technology that has a positive socio-economic effect.
Glavni proizvod anaerobne digestije je bioplin, koji je obnovljivo gorivo, a sporedni proizvod ovog procesa je digestat, koji se koristi kao gnojivo bogato hranjivim tvarima. Dodatni pozitivni učinci ...anaerobne digestije su razgradnja organskog otpada te smanjenje neugodnih mirisa i koncentracije patogenih mikroorganizama. Bioplin se uglavnom koristi za proizvodnju električne energije i topline, a u nekim slučajevima se pročišćava da bi se dobio biometan koji se koristi u mreži prirodnog plina, kao gorivo za motore s unutarnjim sagorijevanjem ili kao polazna kemikalija za kemijsku industriju. Zbog svega navedenog, razvoj proizvodnje bioplina ima pozitivne društveno-ekonomske i ekološke učinke. Bioplin proizveden u Hrvatskoj većinom se koristi za proizvodnju električne i toplinske energije u kogeneracijskim postrojenjima. Iako su u Hrvatskoj dostupne različite obnovljive sirovine koje bi se mogle iskoristiti za proizvodnju bioplina, njihov je potencijal do sada bio nedovoljno iskorišten. Kao sirovine za proizvodnju bioplina u nas se pretežno koriste gnojovka i nusproizvodi poljoprivrede, klaonica i prehrambene industrije. Racionalnijim korištenjem zemljišta i razvojem prehrambene industrije mogla bi se povećati količina poljoprivrednih ostataka i nusproizvoda koji nastaju preradom hrane. Usmjeravanjem i poticanjem korištenja ovih nusproizvoda za anaerobnu digestiju može se stimulirati brži razvoj proizvodnje bioplina u Hrvatskoj. Pored mogućeg povećanja vlastite proizvodnje električne energije i goriva, radi se o ekološki povoljnoj tehnologiji koja ima pozitivan društveno-ekonomski učinak.
The main product of anaerobic digestion is biogas, which is a renewable fuel, and the by-product of this process is digestate, which is used as a nutrient-rich fertilizer. Additional positive effects ...of anaerobic digestion are the decomposition of organic waste and the reduction of unpleasant odors and the concentration of pathogenic microorganisms. Biogas is mainly used for the production of electricity and heat, and in some cases it is purified to obtain biomethane which is used in the natural gas network, as a fuel for internal combustion engines or as a starting chemical for the chemical industry. Due to all of the above, the development of biogas production has positive socio-economic and ecological effects. Biogas produced in Croatia is mostly used for the production of electricity and thermal energy at cogeneration plants. Although various renewable raw materials are available in Croatia that could be used for biogas production, their potential has been underutilized until now. Manure and by-products of agriculture, slaughterhouses and the food industry are mainly used as raw materials for the production of biogas in our country. More rational use of land and development of the food industry could increase the amount of agricultural residues and by-products resulting from food processing. Directing and encouraging the use of these by-products for biogas production can stimulate a faster development of biogas production in our Croatia. In addition to the possible increase in own production of electricity and fuel, it is an environmentally friendly technology that has a positive socio-economic effect.
Ljubičaste nesumporne bakterije zanimljive su s ekološkog i ekonomskog stajališta u održivim biotehnološkim procesima proizvodnje biogoriva, biokemikalija, biopolimera, biomase odnosno sintezi ...specifičnih spojeva kao što su npr. karotenoidi i pigmenti. Za uspostavu ekološki i ekonomski održivih bioprocesa nužan je adekavatan odabir radnih mikroorganizama, sirovina i uvjeta kultivacije, a dobar primjer za to je
razvoj bioprocesa na obnovljivim sirovinama kao što su to lignocelulozne sirovine. U ovom istraživanju proučavan je fotoheterotrofni uzgoj ljubičaste nesumporne bakterije Rhodovulum adriaticum DSM 2781 na tekućim hranjivim podlogama koje sadrže glukozu i/ili ksilozu kao izvore ugljika s ciljem dobivanja bakterijske biomase i
fotosintetskih pigmenata. Rezultati istraživanja pokazuju da su najveće
vrijednosti pokazatelja uspješnosti bioprocesa (YX = 2,095 g L-1; YX/S =
0,54 g g-1i Pr = 0,022 g L-1h-1) vezanih u dobivanje biomase ostvareni kod uzgoja na hranjivoj podlozi s 5 g L-1 glukoze. Uzgoj R. adriaticum DSM 2781 na hranjivoj podlozi s 3 g L-1 glukoze i ksiloze pokazao se najuspješnji za dobivanje fotosintetskih pigmenata (ukupni pigmenti 13,27 mg g-1 biomase) uz zadovoljavajuće ostale pokazatelje uspješnosti bioprocesa (YX = 1,507 g L-1; YX/S = 0,22 g g-1i Pr = 0,017 g L-1h-1).
Purple non-sulphur bacteria are interesting from ecologic and economic point of view in sustainable biotechnological production of biofuels, biochemicals, biopolymers and biomass as well as specific compounds such as carotenoids and pigments. In order to establish ecological and economic sustainable bioprocesses it is necessary to select adequate working microorganisms, raw materials and cultivation conditions. Development of bioprocesses on the renewable raw materials (e.g. lignocellulose containing feedstocks) are good example for such bioprocess types. In this research, the photoheterotrophic cultivation of purple non-sulfur bacteria Rhodovulum adriaticum DSM 2781 was studied on the liquid media containing glucose or /and xylose as a carbon sources in order to produce bacterial biomass and photosynthetic pigments. Results obtained in this study show that the highest values of bioprocess efficiency parameters (YX = 2,095 g L-1 ; YX/S = 0,54 g g-1 i Pr = 0,022 g L-1 h -1 ) related to the biomass production were observed during bacterial cultivation on media with 5 g L-1. Cultivation of R. adriaticum DSM 2781 on the media with 3 g L-1 glucose and xylose shows the highest total photosynthetic pigments content (13,27 mg g-1 biomass) together with satisfy other bioprocess efficiency parameters (YX = 1,507 g L-1 ; YX/S = 0,22 g g-1 i Pr = 0,017 g L-1 h -1 ).
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