Appeal No. 1997-2080
Application No. 08/159,939
Claims 21, 22, 24, 29 through 32 and 35 stand rejected under 35 U.S.C. 103 as
being unpatentable over Shumin Na and Kelly, while claims 7, 23, 33, and 34 stand
rejected 35 U.S.C. 103 as being unpatentable over Shumin Na, Kelly and Kato.
We reverse the examiner’s rejections.
Background
Pullulan, an exopolysaccharide secreted by the fungus Aureobasidium pullulans, is
used in transparent films; oxygen-impermeable, tasteless, odorless coatings for food;
viscosity control agents; etc. Specification, page 1. A characteristic, and undesirable,
property of the fungus is that it produces a melanin-like pigment, dark green to black in
color, which contaminates the pullulan during recovery of the product, necessitating a multi-
step decoloration treatment before the pullulan can be used. An additional undesirable
property is that the average molecular weight of accumulated pullulan decreases as
submerged culture in fermentation broth progresses. Id., page 2.
Aureobasidium pullulans is commonly isolated from forest litter, natural waters,
wood, leather, plant surfaces, etc. It is polymorphic, exhibiting three predominant forms:
elongated branched septate filaments (hyphae); large chlamydospores; and smaller,
elliptical yeast-like single cells. Id., pages 1 and 2. According to appellants, “the pigment
production characteristic of A. pullulans is associated mainly with the filamentous form and
chlamydospores,” rather than the yeast-like form. Moreover, wild-type strains “can be
treated to enrich the fraction of yeast-like cells therein, and the yeast-like cells can be
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