Enhancement of trehalose production in dairy propionibacteria through manipulation of environmental conditions.
We have shown that the ability to produce trehalose is widespread within the genus Propionibacterium. Eighteen strains isolated from dairy sources were screened for trehalose synthesis; the effect of environmental conditions on trehalose production was evaluated in Propionibacterium freudenreichii ssp. shermanii NIZO B365, a strain that accumulated high amounts of this disaccharide. Lactose was the best carbohydrate source for trehalose production, whereas lactate, the substrate that led to the highest specific growth rate, was a poor precursor. Trehalose was consumed after exhaustion of the carbon source in the medium, suggesting its role as a reserve compound. The production of trehalose was not affected by lowering the growth temperature from 30 to 20 degrees C. On the other hand, the maximum trehalose accumulation increased from about 200 to 400 mg of trehalose/g of cell protein upon decreasing the pH from 7.0 to 4.7, by increasing the concentration of NaCl to 2% (w/v), or during growth under aerobic conditions (50% air saturation, 24 microM O(2), pH 7.0). In the absence of NaCl, trehalose accumulated concomitantly with growth, but an increase in salinity triggered a high trehalose production already in the early exponential growth phase. The data provide evidence for a dual function of trehalose as a reserve compound and as a stress-response metabolite. Moreover, P. freudenreichii ssp. shermanii NIZO B365 was able to produce high levels of trehalose in skim milk, which is promising for the implementation of fermented dairy products.
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apartado 127, 2780-156 Oeiras, Portugal. santos@itqb.unl.pt
Filipa S
FS
Cardoso
Paula
P
Gaspar
Jeroen
J
Hugenholtz
Ana
A
Ramos
Helena
H
Santos
D043302:Cultured Milk Products / Q000382:microbiology*; D003611:Dairy Products / Q000382:microbiology*; D005285:Fermentation; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D011424:Propionibacterium / Q000254:growth & development* / Q000378:metabolism*; D013696:Temperature; D014199:Trehalose / Q000096:biosynthesis*
D014199:Trehalose; D007785:Lactose; D010100:Oxygen