1. Introduction
Hyaluronic acid (HA), a polysaccharide, is a high-value biopolymer
with a wide variety of medical and cosmetic applications.
HA belongs to a family of glycosaminoglycan, also known as
mucopolysaccharide. This polymer is comprised of d-glucuronic
acid (GlcUA) and N-acetylglucosamine (GlcNAc) linked by a (1-
3)-glycosidic bond, with the disaccharide repeating units linked by
(1-4)-glycosidic bonds [1,2]. Conventionally, it has been extracted
from animal tissues such as rooster combs and bovine vitreous
humor [3]. However due to limited tissue sources, risks of viral
infection and high cost, HA production from microbial sources
through the fermentation process has received increased attention,
especially when using the gram-positive bacterium Streptococcus
zooepidemicus [3–5].
S. zooepidemicus is a catalase-negative, facultative anaerobe but
is also aerotolerant [6]. In sheep blood agar plates, colonies of these
-hemolytic bacteria will produce a clear zone with HA identified
as mucoid or slimy translucent layer surrounding bacteria colonies.
Under the microscope, these non-sporulating and non-motile bacteria
appear as spherical or ovoid cells that are typically arranged
in pairs or chains surrounded by an extensive extracellular capsule
[5]. The capsule is composed of HA polymers identical to that found
∗