Characteristics and selection of cultures of photosynthetic purple non-sulphur bacteria as a potential 5-aminolevulinic acid producers

Wild strains of purple non-sulphur bacteria: Rhodospirillum rubrum B-6505, Rhodopseudomonas palustris B-6506, Rhodobacter capsulatus B-6508 and Rhodobacter spheroides B-6509 were studied as 5-ALA (5 aminolevulinic acid) producers. Selected strains were subjected to mutagenesis with N-methyl-N-nitro-N-nitrosoguanidine to obtain a strain with high 5-ALA producing capacity. After mutagenesis 19 stable mutant strains were selected from Rhodobacter capsulatus B-6508 and Rhodobacter sphaeroides B-6509. On the basis of obtained results, mutant strain of Rhodobacter capsulatus B-6508 has shown the highest potential for 5-ALA production. The most favorable conditions for growth and 5-ALA production by mutant strain R. capsulatus B-6508 were observed in media composed of glutamate and malate, light at 2000 Lux, microaerophilic conditions and temperature of 28 °C. In these conditions, the highest 5-ALA concentration (179 mg/L) was detected together with the highest bacterial physiological activity. The prolongation of mutant strain R. capsulatus B-6508 cultivation time after glycine, succinate and levulinic acid addition is related to the reduction of 5-ALA concentrations (e.g. 124.5 mg/L after 48 h and 89.5 mg/L after 72 hours). In the light/aerobic conditions R. capsulatus B-6508 produced only 58.1 mg/L of 5 ALA. Furthermore, in dark conditions even lower biomass and 5-ALA concentrations were observed during R. capsulatus B-6508 cultivation

Characteristics and selection of cultures of photosynthetic purple non-sulphur bacteria as a potential 5-aminolevulinic acid producers

Wild strains of purple non-sulphur bacteria: Rhodospirillum rubrum B-6505, Rhodopseudomonas palustris B-6506, Rhodobacter capsulatus B-6508 and Rhodobacter spheroides B-6509 were studied as 5-ALA (5 aminolevulinic acid) producers. Selected strains were subjected to mutagenesis with N-methyl-N-nitro-N-nitrosoguanidine to obtain a strain with high 5-ALA producing capacity. After mutagenesis 19 stable mutant strains were selected from Rhodobacter capsulatus B-6508 and Rhodobacter sphaeroides B-6509. On the basis of obtained results, mutant strain of Rhodobacter capsulatus B-6508 has shown the highest potential for 5-ALA production. The most favorable conditions for growth and 5-ALA production by mutant strain R. capsulatus B-6508 were observed in media composed of glutamate and malate, light at 2000 Lux, microaerophilic conditions and temperature of 28 °C. In these conditions, the highest 5-ALA concentration (179 mg/L) was detected together with the highest bacterial physiological activity. The prolongation of mutant strain R. capsulatus B-6508 cultivation time after glycine, succinate and levulinic acid addition is related to the reduction of 5-ALA concentrations (e.g. 124.5 mg/L after 48 h and 89.5 mg/L after 72 hours). In the light/aerobic conditions R. capsulatus B-6508 produced only 58.1 mg/L of 5 ALA. Furthermore, in dark conditions even lower biomass and 5-ALA concentrations were observed during R. capsulatus B-6508 cultivation

The Effect of Total Oxygen Concentraction in the Bottle on the Beer Quality During Storage

U ovom istraživanju provedeno je ispitivanje utjecaja ukupne koncentracije kisika u staklenoj boci na kakvoću piva donjeg vrenja tijekom skladištenja. Pivo je bilo skladišteno na temperaturi od 22 - 25°C u tamnoj prostoriji, a u pivu je bio prisutan kisik u tri različite ukupne početne koncentracije: 0,09 mg/L, 0,29 mg/L i 0,63 mg/L. Tijekom skladištenja (98 dana) u pivu je praćena promjena koncentracije trans-2-nonenala kao indikatora procesa oksidacije (starenja) piva, a dobiveni rezultati pokazuju da koncentracija trans-2-nonenala nije direktno ovisna o ukupnoj koncentraciji kisika u boci piva. U ovom istraživanju provedena je i senzorska analiza uzoraka piva koja je pokazala da povećane ukupne koncentracije kisika u boci izravno utječu na ocjenu kakvoće piva.In this research the effect of total packaging oxygen on the quality of bottled (glass bottle) lager beer during storage was studied. The beer was stored in a dark room at temperature of 22 - 25°C and it contained three different concentrations of total packaging oxygen: 0,09, 0,29 and 0,63 mg/L. During the 98 days storage period the concentration of trans-2-nonenal, a well known indicator of oxidation processes in the beer, was monitored. The results obtained in this research clearly show that the concentration of trans-2-nonenal is not directly related to the total oxygen concentration in the bottled beer. Sensory analysis of beer was also performed and obtained results clearly show that higher concentrations of total packaging oxygen directly effects beer quality and flavour

Comparison Between Different Cultivation Techniques for Bioethanol Production from Raw Sugar Beet Juice

U ovom istraživanju proučavana je proizvodnja bioetanola na svježem soku šećerne repe s pomoću kvasca Saccharomyces cerevisiae. Za vođenje procesa proizvodnje bioetanola primjenjene su ove tehnike: šaržni proces, šaržni proces s pritokom supstrata i polukontinuirani proces. Tijekom šaržnog procesa proizvodnje bioetanola stupanj konverzije supstrata u produkt (YP/S) je iznosio 0,375 g/g, učinkovitost bioprocesa (E) 69.70 %, te produktivnost (Pr) procesa 0,53 g/Lh. U šaržnom procesu s pritokom supstrata dobivene su ove vrijednosti pokazatelja uspješnosti bioprocesa: YP/S = 0,502 g/g, E = 93,40 % i Pr = 0,50 g/Lh. Nadalje, tijekom polukontinuirane proizvodnje bioetanola pokazatelji uspješnosti bioprocesa su imali ove vrijednosti: YP/S = 0,360 g/g, E = 66,91 % i Pr = 0,66 g/Lh. Na osnovi prethodno prikazanih rezultata jasno je da šaržni proces s pritokom supstrata i polukontinuirani proces imaju značajno veći potencijal za primjenu u industrijskoj proizvodnji bioetanola iako je potrebna daljnja optimizacija polukontinuirane tehnike vođenja bioprocesa.In this investigation, the production of bioethanol on the raw sugar beet juice by Saccharomyces cerevisiae was studied. Following cultivation techniques for bioethanol productions were used: batch, fed batch and repeated batch. In batch process substrate conversion coefficient (YP/S) was 0,375 g/g, bioprocess effi eciency (E) 69,70 % and productivity (Pr) 0,53 g/Lh, respectively. During fed batch process bioprocess efficiency parameters have following values: YP/S = 0,502 g/g, E = 93,4 % and Pr = 0,50 g/Lh. Furthermore, in repeated batch process bioprocess efficiency parameters have following values: YP/S = 0,360 g/g, E = 66,91 % and Pr = 0,66 g/Lh. On the basis of previously presented results it is clear that fed batch and repeated batch processes have considerably higher potential for use in the industrial bioethanol production although further optimization of repeated batch cultivation techniques has to be performed

Ethanol production from different intermediates of sugar beet processing

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

Photoheterotrophic cultivation of purple non-sulphur bacterium Rhodovulum adriaticum on the media with different carbon sources

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-1i Pr = 0,022 g L-1h-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-1i Pr = 0,017 g L-1h-1)

Proizvodnja etanola iz različitih međuproizvoda obrade šećerne repe

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.U ovom je istraživanju proučavan proces proizvodnje etanola iz sirovoga soka i sirovih rezanaca šećerne repe. Tijekom proizvodnje etanola iz sirovoga soka u bioreaktoru s miješalom primijenjeni su ovi načini vođenja bioprocesa: šaržni i šaržni proces s pritokom supstrata. Pri proizvodnji etanola iz sirovih rezanaca u horizontalnom rotirajućem cijevnom bioreaktoru primijenjena je šaržna tehnika vođenja bioprocesa. U oba je ova istraživanja kao radni mikroorganizam upotrijebljen kvasac Saccharomyces cerevisiae. Tijekom šaržnog procesa proizvodnje etanola iz sirovoga soka prinos je etanola iznosio 59,89 g/L, a učinkovitost bioprocesa bila 78,8 %. U šaržnom procesu s pritokom supstrata dobiven je prinos etanola od 92,78 g/L uz učinkovitost bioprocesa od 93,4 %. Istodobno je pri proizvodnji etanola iz sirovih rezanaca šećerne repe u horizontalnom rotirajućem cijevnom bioreaktoru s inokulumom od 16,7 % (V/m) dobiven najveći prinos etanola od 54,53 g/L uz učinkovitost bioprocesa od 79,5 %. Rezultati istraživanja jasno pokazuju da se oba međuproizvoda obrade šećerne repe mogu uspješno primijeniti u proizvodnji etanola

Anaerobni uzgoj kvasca Saccharomyces cerevisiae na hidrolizatima lignoceluloznih sirovina

Zbog velike rasprostranjenosti u prirodi i relativno niske cijene, lignocelulozne sirovine postaju zanimljive za primjenu u različitim biotehnološkim procesima. Međutim, zbog svoje kompleksne strukture, te sirovine moraju proći postupak predobradbe u kojem uglavnom nastaju nuspodukti koji imaju inhibitorno djelovanje na proizvodni mikroorganizam i time utječu na ukupnu učinkovitost bioprocesa. U ovom istraživanju ispitivana je mogućnost korištenja hidrolizata pšenične slame i kukuruzovine za anaerobni uzgoj kvasca S. cerevisiae odnosno s ciljem proizvodnje etanola. Postupak blago kisele predobrade lignoceluloznih sirovina u visokotlačnom reaktoru (pri 210°C; 20 bara; vrijeme zadržavanja 1 - 10 minuta; do 1,0 % H2SO4) korišten je za dobivanje hidrolizata lignoceluloznih sirovima pri čemu je najveći udjel ukupnih fermentabilnih šećera zabilježen kod postupka predobrade s 1,0 % H2SO4 i vremenom zadržavanja od 5 minuta. Anaerobni uzgoj kvasca na hranjivim podlogama s hidrolizatima lignoceluloznih sirovina proveden je u Erlenmeyer tikvicama, te dodatno testiran u horizontalnom rotirajućem cijevnom bioreaktoru (HRCB). Rezultati ovog istraživanja pokazuju da su veće vrijednosti pokazatelja uspješnosti anaerobnog uzgoja kvasca zabilježene na hranjivoj podlozi s hidrolizatom pšenične slame (u odnosu na hidrolizat kukuruzovine) u HRCB-u pri čemu su ostvarene ove vrijednosti pokazatelja uspješnosti bioprocesa: YP/S = 0,261 g g-1, Pr = 0,0678 g L-1h-1 i E= 42 %. Na osnovi rezultata ovog istraživanja vidljivo je da je potrebno dodatno optimizirati postupak predobrade lignoceluloznih sirovina kao i selekcionirati novi soj mikroorganizma koji ima sposobnost korištenja heksoza i pentoza odnosno visoku tolerantnost na nusprodukte koji nastaju postupkom predobrade lignoceluloznih sirovina

Positive socio-economic and ecological effects of biogas production by anaerobic digestion

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

Mathematical modelling of bioethanol production from raw sugar beet cossettes in a horizontal rotating tubular bioreactor

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