Background: The alga
Laminaria japonica is the most economically important brown seaweed cultured in China,
which is used as food and aquatic animal feedstuff. However, the use of
L. japonica as a feedstuff in
Apostichopus japonicas farming is not ideal because
A. japonicas does not produce enough enzyme activity for
degrading the large amount of algin present in
L. japonica. In this study, semi solid fermentation of the
L. japonica feedstuff employing a
Bacillus strain as the microbe was used to as a mean to degrade the algin
content in
L. japonica feedstuff.
Results: The
Bacillus strain,
Bacillus amyloliquefaciens
WB1, was isolated by virtue of its ability to utilize sodium
alginate as the sole carbon source. Eight factors affecting growth and algin-degrading capacity of WB1 were
investigated. The results of Plackett–Burman design indicated that fermentation time, beef extract, and solvent
to solid ratio were the significant parameters. Furthermore, the mutual interaction between the solvent to
solid ratio and beef extract concentration was more significant than the other pairs of parameters on algin
degradation. Optimal values obtained from Central-Composite Design were 113.94 h for fermentation time,
0.3% (w/v) beef extract and 44.87 (v/w) ratio of solvent to feedstuff. Under optimal conditions, 56.88% of the
algin was degraded when a 50-fold scale-up fermentation was carried out, using a 5-L fermenter.
Conclusions: This study provides an alternative and economical way to reduce the algin content in
L. japonica
through degradation by WB1, making it a promising potential source of feed for cultured
L. japonica .
