Pigment stability studies in selected pigment-producing microbes from New Zealand environment

The industrial production of natural food colourants is already well-established and expanding. However, the range of natural colour-shades is still limited compared to synthetic dyes. Besides, the use of plant extracts is known to be expensive and uncompetitive to synthetic dyes due to their high production costs. Consequently, microorganisms are becoming a more popular alternative source for natural food grade pigments. Development of microbial food grade pigments are likely to cut down the high production cost of natural colours, thus leading to a cheaper source of natural food colourants among the modern consumers. Preceding commercialization, pigment stability and toxicity assessment are required in order to determine their suitability to the food industry. We, therefore, have screened 286 pigment-producing microbial strains isolated from New Zealand environment. Based on water solubility and colour-shades of interest, 41 pigments have been short-listed for pigment stability tests towards different pHs, temperatures and light. To date, our current results showed that 81% of the yellow-to-reddish water-soluble pigments and the red SVB-B50 water-insoluble pigment were stable at all ranges of temperature i.e. -20oC, 4oC, 60oC, 100oC and microwave heat. Light and pH stability tests are being carried out. Further to this study, metabolomics tools will be incorporated to elucidate the metabolic pathway for biosynthesis of a selected microbial pigment with most potential for industrial application, and metabolic engineering strategies will be determined aiming for improvement of the pigment production yields during fermentation

Pigment production by New Zealand microbes: screening and industrial application

Industrial production of natural food colorants by microbial fermentation has several advantages such as cheaper production, possibly easier extraction, higher yields through strain improvement, no lack of raw materials and no seasonal variations. Development of microbial food grade pigments are likely to cut down the high production cost of natural pigments, thus leading to a cheaper source of natural food colorants among the modern consumers. Until recently, the use of plant extracts is known to be expensive and uncompetitive to synthetic dyes due to their high production costs. We, therefore, have screened 284 microbial strains from our New Zealand environmental strain collection. Among those, 166 strains produced colored pigments when growing in liquid medium. Twenty-eight pigments were found to be extracellular pigments while 89 presented intracellular pigments. HPLC results showed that 33 purified pigments (approximately 28%) were water-soluble. On the basis of color shades and water solubility of pigments, 39 microbial strains have been selected for further studies. We have used ribosomal RNA sequences to identify the selected strains. Preliminary results showed the presence of representatives from 20 different genera (E-value = 0, Max Ident = 93—100%) namely Paracoccus, Saccharomyces, Cladosporium, Brevundimonas, Microbacterium, Pseudomonas, Flavobacterium, Leifsonia, Chryseobacterium, Sphingopyxis, Serratia, Erythrobacter, Pedobacter, Micrococcus, Stenotrophomonas, Pantoea, Janthinobacterium, Methylobacterium, Sandarakinorhabdus and Mycobacterium. Tests for biological activity and pigment stability are being carried out to shortlist those natural pigments with greatest potential for industrial application

A low-gluten diet induces changes in the intestinal microbiome of healthy Danish adults

\ua9 2018, The Author(s). Adherence to a low-gluten diet has become increasingly common in parts of the general population. However, the effects of reducing gluten-rich food items including wheat, barley and rye cereals in healthy adults are unclear. Here, we undertook a randomised, controlled, cross-over trial involving 60 middle-aged Danish adults without known disorders with two 8-week interventions comparing a low-gluten diet (2 g gluten per day) and a high-gluten diet (18 g gluten per day), separated by a washout period of at least six weeks with habitual diet (12 g gluten per day). We find that, in comparison with a high-gluten diet, a low-gluten diet induces moderate changes in the intestinal microbiome, reduces fasting and postprandial hydrogen exhalation, and leads to improvements in self-reported bloating. These observations suggest that most of the effects of a low-gluten diet in non-coeliac adults may be driven by qualitative changes in dietary fibres