A microfiltration bioreactor to achieve high cell density in Sulfolobus solfataricus fermentation

Schiraldi, Chiara; Marulli, F.; Lernia, Isabella Di; Martino, Ascanio; Rosa, Mario De

doi:10.1007/s007920050117

Cited by 45 publications

(28 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There was no cell growth in the presence of PGA concentrations greater than 15.5 mM in GM medium. According to a recent study of a high-density culture of S. solfataricus in which a microfiltration bioreactor was used (26), toxic compounds with molecular masses less than 1 kDa were produced during fermentation and reduced the maximum cell density. In view of the results presented in this paper, it is very probable that PGA (molecular weight, 129.1) is one of the toxic compounds that accumulate in culture broth.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

l -Pyroglutamate Spontaneously Formed from l -Glutamate Inhibits Growth of the Hyperthermophilic Archaeon Sulfolobus solfataricus

Park

Lee

Ryu

2001

Appl Environ Microbiol

View full text Add to dashboard Cite

Identification of physiological and environmental factors that limit efficient growth of hyperthermophiles is important for practical application of these organisms to the production of useful enzymes or metabolites. During fed-batch cultivation of Sulfolobus solfataricus in medium containing L-glutamate, we observed formation of L-pyroglutamic acid (PGA). PGA formed spontaneously from L-glutamate under culture conditions (78°C and pH 3.0), and the PGA formation rate was much higher at an acidic or alkaline pH than at neutral pH. It was also found that PGA is a potent inhibitor of S. solfataricus growth. The cell growth rate was reduced by one-half by the presence of 5.1 mM PGA, and no growth was observed in the presence of 15.5 mM PGA. On the other hand, the inhibitory effect of PGA on cell growth was alleviated by addition of L-glutamate or L-aspartate to the medium. PGA was also produced from the L-glutamate in yeast extract; the PGA content increased to 8.5% (wt/wt) after 80 h of incubation of a yeast extract solution at 78°C and pH 3.0. In medium supplemented with yeast extract, cell growth was optimal in the presence of 3.0 g of yeast extract per liter, and higher yeast extract concentrations resulted in reduced cell yields. The extents of cell growth inhibition at yeast extract concentrations above the optimal concentration were correlated with the PGA concentration in the culture broth. Although other structural analogues of L-glutamate, such as L-methionine sulfoxide, glutaric acid, succinic acid, and L-glutamic acid ␥-methyl ester, also inhibited the growth of S. solfataricus, the greatest cell growth inhibition was observed with PGA. We also observed that unlike other glutamate analogues, N-acetyl-L-glutamate enhanced the growth of S. solfataricus. This compound was stable under cell culture conditions, and replacement of L-glutamate with N-acetyl-L-glutamate in the medium resulted in increased cell density.Recently, hyperthermophiles have attracted the attention of many workers in the biotechnology research community because of the potential industrial applications of these organisms and because they may provide a better understanding of how cell components are stabilized when they are heated (1,13,18,28,29). Despite the biotechnological potential of hyperthermophiles, thus far the uses of these organisms have been limited because of the low cell yields when they are cultivated, which are attributed mainly to a lack of knowledge concerning the physiological characteristics and high-temperature cultivation techniques (5, 17). Therefore, identification of physiological and environmental factors that limit efficient growth of hyperthermophiles and development of strategies to obtain high cell densities under high-temperature conditions are particularly important for increasing the biomass yields of these microorganisms in environments different from their natural habitats.Sulfolobus solfataricus P2 is a hyperthermophilic archaeon which normally grows at 75 to 85°C and pH 2.0 to 4.0 (4, 7, 32). Since phy...

show abstract

Section: Discussionmentioning

confidence: 99%

“…In view of the results presented in this paper, it is very probable that PGA (molecular weight, 129.1) is one of the toxic compounds that accumulate in culture broth. It is noteworthy that a complex nutrient, such as yeast extract, which contains a large amount of L-glutamate, was added continuously in the study of Schiraldi et al (26).…”

Section: Discussionmentioning

confidence: 99%

l -Pyroglutamate Spontaneously Formed from l -Glutamate Inhibits Growth of the Hyperthermophilic Archaeon Sulfolobus solfataricus

Park

Lee

Ryu

2001

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…Prior to fermentation, the MF modules were sterilized in situ together with the medium. After cell harvesting and vessel washing, the MF modules were cleaned with de-ionized water at 80°C for 2 h reversing flux direction, the standard restoring procedure was performed successively (Schiraldi et al, 1999). During cultivation backflushings were operated by simply inverting flux for 1-2 min every 30 min during the first 8 h of the microfiltration phase; successively, a solution containing the salts of the medium recipe was pumped reversing the flux to increase the cleaning efficiency.…”

Section: Microfiltration Bioreactor Configurationmentioning

confidence: 99%

High cell density cultivation of probiotics and lactic acid production

Schiraldi

Adduci

Valli

et al. 2003

Biotech & Bioengineering

Self Cite

View full text Add to dashboard Cite

The commercial interest in functional foods that contain live microorganisms, also named probiotics, is paralleled by the increasing scientific attention to their functionality in the digestive tract. This is especially true of yogurts that contain strains of lactic-acid bacteria of intestinal origin, among these, Lactobacillus delbrueckii ssp. bulgaricus is extensively used in the dairy industry and it has been demonstrated to be a probiotic strain. In this work we describe high cell density cultivations of this microorganism also focusing on the stereospecific production of lactic acid. Key parameters such as medium composition (bactocasitone concentration) and diverse aeration conditions were explored. The results showed that the final concentration of biomass in anaerobic fermentation was lower than the one obtained in microaerophilic conditions, while it gave a very high productivity of lactic acid which was present as a racemic mixture in the permeate. Fermentation experiments carried out with air sparging, even at very low flow-rate, led to the production of the sole L(+) lactic acid giving sevenfold increase in biomass yield in respect to the batch cultivation. Finally, a mathematical model was developed to describe the microfiltration bioprocess applied in this research considering an inhibition kinetic and enucleating a suitable mathematical description for the decrease of the transmembrane flux.

show abstract

“…The cells maintained active synthesis of reporter enzymes of industrial interest, including α-glucosidase, β-glycosidase and alcohol dehydrogenase (Schiraldi et al 1999). Although we obtained improved biomass yield with the MF bioreactor, production of the enzymes of interest was low because of the long doubling time (t d ) of Sulfolobus (7 < t d < 18 h) and the low expression ARCHAEA ONLINE at http://archaea.ws BIOTECHNOLOGICAL APPLICATIONS OF ARCHAEA 77 levels of these enzymes.…”

Section: Innovative Fermentation Processes For the Production Of Archmentioning

confidence: 99%

Perspectives on biotechnological applications of archaea

Schiraldi

Giuliano

Rosa

2002

Archaea

Self Cite

100

View full text Add to dashboard Cite

Summary Many archaea colonize extreme environments. They include hyperthermophiles, sulfur-metabolizing thermophiles, extreme halophiles and methanogens. Because extremophilic microorganisms have unusual properties, they are a potentially valuable resource in the development of novel biotechnological processes. Despite extensive research, however, there are few existing industrial applications of either archaeal biomass or archaeal enzymes. This review summarizes current knowledge about the biotechnological uses of archaea and archaeal enzymes with special attention to potential applications that are the subject of current experimental evaluation. Topics covered include cultivation methods, recent achievements in genomics, which are of key importance for the development of new biotechnological tools, and the application of wild-type biomasses, engineered microorganisms, enzymes and specific metabolites in particular bioprocesses of industrial interest.

show abstract

A microfiltration bioreactor to achieve high cell density in Sulfolobus solfataricus fermentation

Cited by 45 publications

References 8 publications

l -Pyroglutamate Spontaneously Formed from l -Glutamate Inhibits Growth of the Hyperthermophilic Archaeon Sulfolobus solfataricus

l -Pyroglutamate Spontaneously Formed from l -Glutamate Inhibits Growth of the Hyperthermophilic Archaeon Sulfolobus solfataricus

High cell density cultivation of probiotics and lactic acid production

Perspectives on biotechnological applications of archaea

Contact Info

Product

Resources

About