Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2017 May 23;16(1):91.
doi: 10.1186/s12934-017-0703-z.

Effect of bacteria type and sucrose concentration on levan yield and its molecular weight

Álvaro González-Garcinuño  1 , Antonio Tabernero  1 , José Mª Sánchez-Álvarez  1 , Miguel A Galán  1 , Eva M Martin Del Valle  2
Affiliations

Effect of bacteria type and sucrose concentration on levan yield and its molecular weight

Álvaro González-Garcinuño et al. Microb Cell Fact. .

Abstract

Background: Levan has been traditionally produced from microorganism. However, there is a continuous effort in looking for new strains that improve levan production yield and uses alternative sugar sources for growth. Despite having a wide range of data about levan yield, there are not papers which allow controlling molecular weight, and that plays an essential role for further applications.

Results: The effect of the sucrose concentration on levan yield (and its molecular weight) from Bacillus atrophaeus and Acinetobacter nectaris (Gram positive and Gram negative respectively) was studied in this work. It was found that A. nectaris growth (from 3 to 1.5 g L-1 in 40 h) and its levan production (from 3 to 1.5 g L-1) decreases by increasing sucrose concentration (best results at a concentration of 120 g L-1) whereas B. atrophaeus growth (3.5 g L-1 in 30 h) and its levan production (also 3.5 g L-1) were not affected by modifying that parameter. Levan molecular weight from A. nectaris decreases by increasing sucrose concentration (from 8000 to 2000 kDa) whereas levan molecular weight from B. Atrophaeus remains always around 50 kDa. By performing a kinetic study, it was shown that A. nectaris growth follows a substrate-inhibition model, whereas Monod equation provided a good fit for B. atrophaeus growth. Finally, wastes from orange juice industry were used as a medium culture to cultivate those microorganism, obtaining good results with B. atrophaeus (growth 3 g L-1 in 30 h).

Conclusions: Levan production kinetics was determined and compared between different bacteria types.

Keywords: Byproducts; Kinetics; Levan; Molecular weight.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
Sucrose concentration effect on microbial growth. a Effect on A. nectaris. b Effect on B. atrophaeus
Fig. 2
Fig. 2
Sucrose concentration effect on levan synthesis. a Effect on A. nectaris; b effect on B. atrophaeus
Fig. 3
Fig. 3
Characterization of levan obtained. a Infrared spectrum, b H-MRN, c C-MRN
Fig. 4
Fig. 4
Levan molecular weight depending on sucrose initial concentration
Fig. 5
Fig. 5
Effect of glucose on levan formation from A. nectaris
Fig. 6
Fig. 6
Bacteria growth on byproducts from juice factories
Fig. 7
Fig. 7
Schematic vision of method proposed. In Gram negative bacteria, sucrose and products are imbibed in periplasmic space, and there is mass transfer opposition for go away to culture broth. This fact does not occur with Gram positive bacteria, where enzyme is directly in contact with culture broth. M membrane, IM inner membrane, OM outer membrane, PW peptidoglycan wall, LS levansucrase
See this image and copyright information in PMC

References

    1. Srikanth S, Sundhar Reddy CHSS, Siddartha G, Ramaiah MJ, Babu Uppuluri K. Review on production, characterization and applications of microbial levan. Carbohydr Polym. 2015;120:102–114. doi: 10.1016/j.carbpol.2014.12.003. - DOI - PubMed
    1. Gupta SK, Pal AK, Sahu NP, Dalvi RS, Akhtar MS, Jha AK, Baruah SK. Dietary microbial levan enhances tolerance of Labeo rohita (Hamilton) juveniles to thermal stress. Aquaculture. 2010;306:398–402. doi: 10.1016/j.aquaculture.2010.06.008. - DOI
    1. Poli A, Kazak H, Gürleyendag B, Tommonaro G, Pieretti G, Öner ET, Nicolaus B. High level synthesis of levan by a novel Halomonas species growing on defined media. Carbohydr Polym. 2009;78:651–657. doi: 10.1016/j.carbpol.2009.05.031. - DOI
    1. Jathore NR, Bule MV, Tilay AV, Annapure US. Microbial levan from Pseudomonas fluorescens: characterization and medium optimization for enhanced production. Food Sci Biotechnol. 2012;21:1045–1053. doi: 10.1007/s10068-012-0136-8. - DOI
    1. Silbir S, Dagbagli S, Yegin S, Baysal T, Goksungur Y. Levan production by Zymomonas mobilis in batch and continuous fermentation systems. Carbohydr Polym. 2014;99:454–461. doi: 10.1016/j.carbpol.2013.08.031. - DOI - PubMed

LinkOut - more resources