One-Step Process for Environment-Friendly Preparation of Agar Oligosaccharides From Gracilaria lemaneiformis by the Action of Flammeovirga sp. OC4

• Published in: Frontiers in microbiology Vol. 10; p. 724
• Main Authors: Chen, Xinglin, Li, Li, Chan, Zhuhua, Zeng, Runying, Lin, Mengshi, Lin, Hetong
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 17-04-2019
• Subjects: Flammeovirga sp. OC4; Gracilaria lemaneiformis; Microbiology; oligosaccharides; one-step process; optimization; response surface methodology; one-step process; Flammeovirga sp. OC4; response surface methodology; optimization; oligosaccharides; Gracilaria lemaneiformis
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2019.00724

Oligosaccharides extracted from agar
(
) have stronger physiological activities and a higher value than agar itself, but the pollution caused by the extraction process greatly restricts the sustainable use of agar. In this study, four bacterial strains with a high ability to degrade
were isolated from seawater by
enrichment in the deep sea. Among them,
sp. OC4, identified by morphological observation and its 16S rRNA sequencing (98.07% similarity to type strain JL-4 of
), was selected. The optimum temperature and pH of crude enzyme produced by
sp. OC4 were 50°C and 8, respectively. More than 60% of the maximum enzyme activity remained after storage at pH 5.0-10.0 for 60 min. Both Mn
and Ba
could enhance the enzyme activity. A "one-step process" for preparation of oligosaccharides from
was established using
sp. OC4. After optimization of the Plackett-Burman (PB) design and response surface methodology (RSM), the yield of oligosaccharides was increased by 36.1% from 2.71 to 3.09 g L
in a 250-mL fermenter with optimized parameters: 30 g L
powder, 4.84 g L
(NH4)
SO
, 44.8-mL working medium volume at 36.7°C, and a shaking speed of 200 ×
for 42 h. The extracted oligosaccharides were identified by thin layer chromatography (TLC) and ion chromatography, which consisted of neoagarobiose, agarotriose, neoagarotetraose, agaropentaose, and neoagarohexaose. These results provided an alternative approach for environment-friendly and sustainable utilization of algae.