Conversion of Ulva fronds to a hatchery diet for Artemia nauplii utilizing the degrading and attaching abilities of Pseudoalteromonas espejiana

Abstract

An algal suspension containing protoplasmic detritus [termed, single cell detritus (SCD)] was prepared from freeze-dried fronds of Ulva and its dietary value to Artemia nauplii was tested after size fractionation. The dissolved fraction (<0.22 µm) ofthe Ulva suspension contained ca. 48% of theoriginal protein in the Ulva, but had no dietaryvalue to Artemia, which is a suspension feeder. In contrast, the fraction passing through a 100-µm meshand containing SCD of 2–14 µm in diameter, contributedto the survival of Artemia. The fraction remaining on the 100 µm mesh was further incubated with and without the bacterium Pseudoalteromonas espejiana strain AR06 FERM BP-5024. The bacterium degraded Ulva forming new SCD over 106 mL -1 level as rapidly as by 16 h of incubation. The dietary value of Ulva for Artemia growth was elevated over four times by the incubation. The protein content of the SCD was approximately doubled by the attaching of bacteria, suggesting the enhanced Artemia growth is attributable to the combined effect of the SCD and the bacteria. Development of a hatchery diet from Ulva , a resource with a low commercial value, is suggested utilizing the degrading and attaching ability of P. espejiana.