Award details

13TSB_N4L2: CELLDEX - Development of a low calorie bulk sugar replacer

Reference	BB/M013766/1
Principal Investigator / Supervisor	Professor Harry Flint
Co-Investigators / Co-Supervisors	Dr Petra Louis
Institution	University of Aberdeen
Department	Rowett Institute of Nutrition and Health
Funding type	Research
Value (£)	49,119
Status	Completed
Type	Research Grant
Start date	01/12/2014
End date	31/05/2015
Duration	6 months

Abstract

Technical Summary The TSB project CELLDEX will investigate whether cellodextrins can be used as sugar replacers in certain human foodstuffs. Cellodextrins are beta (1-4) linked glucose polymers (the same primary structure as in cellulose) that cannot be degraded by human digestive enzymes. They will therefore arrive in the large intestine where they may be subject to microbial fermentation. The purpose of this part of the project (WP3.1) is to determine the likely rate and extent of such fermentation using in vitro approaches, and to predict the likely impact of cellodextrins upon microbial community composition and metabolic outputs. Cellodextrins will be provided as the sole added energy source to batch cultures of anaerobic medium (prepared under 100% CO2) inoculated with human faecal microbiota, and the resulting fermentation compared with that of replicate cultures provided with cellulose or soluble starch. Continuous flow fermentor models may also be employed to investigate the effect of pH on the fermentation. Microbial community composition will be monitored for the inoculum and after 48h incubation by qPCR, using a panel of primers developed by the RINH Microbiology group. High throughput sequencing of 16S rRNA amplicons using signature tagged primers may also be applied if required to obtain more detailed information. The major products of fermentation, short chain fatty acids and gases, will be monitored by gas chromatography and cellodextrin utilization will be monitored by the analysis of total sugars. Genome sequences are available for a range of dominant polysaccharide-utilizing anaerobes that have been isolated in our laboratory from the human colon. Those possessing candidate cellulase genes will be tested for their ability to grow with cellodextrins as a sole energy source.

Summary

The Microbiology Group at RINH (U. Aberdeen) will perform a key element (WP3.1- "Assessment of cellodextrin fermentability by human colonic bacteria in vitro") of Work package 3 within the TSB project CELLDEX. They will use in vitro approaches to assess the fermentability of cellodextrins by human intestinal microorganisms and to predict the likely impact of cellodextrins upon microbial community composition and metabolic outputs. Cellodextrins will be incubated with mixed human faecal microbiota under anaerobic conditions using batch cultures and pH-controlled continuous flow fermentor models. Molecular approaches will be used to monitor changes in microbial community composition. The major products of fermentation, short chain fatty acids and gases, will be monitored by gas chromatography and cellodextrin utilization will be monitored by analysis of total sugars. The ability of a range of dominant polysaccharide-utilizing anaerobes that have been isolated in our laboratory from from the human colon to grow with cellodextrins as a sole energy source will also be assessed here. Together with the results from molecular community analysis, this should provide information on species likely to be responsible for cellodextrin utilization. This work will precede and inform the planned human dietary intervention studies to be performed by University of Nottingham.

Impact Summary

The long term potential impact of this work is to benefit public health by providing a safe and acceptable bulk sugar replacer that might be used in a variety of foodstuffs. Such products can play an important role in combating obesity and diabetes in the UK population by helping people to decrease their dietary intake of sugars and total energy. By assessing the fermentability of cellodextrins, we will be helping to establish acceptable levels of intake that avoid possible problems due to microbial activity in the large intestine. The work will of course benefit the food producer by allowing them to introduce lower calorie alternatives to existing products and therefore to market new products for the weight-conscious customer. Cellodextrins can be derived by enzymatic and/or chemical action from waste biomass and therefore represent an environmentally sustainable solution.

Committee	Not funded via Committee
Research Topics	Diet and Health, Microbiology
Research Priority	X – Research Priority information not available
Research Initiative	Innovate UK (TSB) [2011-2015]
Funding Scheme	X – not Funded via a specific Funding Scheme

Associated awards:

BB/L025019/1 13TSB_N4L2CRD: CELLDEX-Developement of a low calorie bulk sugar replacer

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