Title: Alternative Sweeteners

426 Richards and Dexter
from assays performed by HBC (1997) give a specific rotation equal to [α] 20 D:
199° (c 5).
VI. PRODUCTION OF TREHALOSE
A. Historical Processes for Trehalose Production
The isolation of trehalose from natural sources has been ongoing for several decades.
Historically, the production of trehalose has been limited to small quantities
obtained by extraction from microorganisms such as baker’s yeast (1, 15,
16, 17). One complex purification method produced maximum yields of 0.7%,
whereas later procedures resulted in yields of up to 16% of active dried yeast
(92% solids) (15, 17).
Recently, investigators have focused on the use of bacterial synthesis,
transgenic technology, or enzymatic conversion for the production of trehalose
(5). Trehalose has been isolated during the fermentation of n-alkanes by Arthrobacter
sp. in quantities of 5–6 g/l (18). Three Japanese patents, issued between
1975 and 1993, described the production of trehalose by bacteria using common
carbon sources such as glucose and sucrose. Genetic recombination has been
attempted by insertion of a gene that converts glucose into trehalose in a sugarproducing
crop (5). Murao et al. reported on an enzymatic method for producing
trehalose from maltose using trehalose- and maltose-phosphorylases, which provided
a yield of 60% (19). Trehalose has also been produced enzymatically by
a combination of acid reversion of d-glucose and trehalose (5, 20).
Although these newer methods have reduced the cost of trehalose, they
have not been able to provide trehalose at a cost low enough for use in most
food applications. This has effectively restricted its use to research, pharmaceuticals,
and high-value cosmetics.
B. The Hayashibara Manufacturing Process
Hayashibara Biochemical Laboratories of Okayama, Japan, screened soil samples
for bacteria that could produce trehalose from relatively inexpensive carbon
sources such as starch or maltose.
One group of bacteria were shown to convert maltose to trehalose in a
manner that was more efficient than previously reported enzyme systems (19,
21). A second bacterial group was found to use starch as the substrate for trehalose
production (22, 23). Hayashibara scientists isolated and characterized the
two different trehalose-producing enzyme systems from these organisms (21–
23). Those species that produced trehalose directly from maltose required only
one novel enzyme, trehalose-synthase (21). The bacteria that produced trehalose