Microbial degradation of kelp waste by cooperation of alginate and cellulose hydrolyzing bacteria: A potential solution for kelp waste reutilization

There has been a growing demand for efficient disposal of kelp waste. Microbial degradation is a win–win bio-solution for seaweeds waste disposal and acquisition of nutritious byproducts. In this study, the cooperation of an alginate lyase producing bacteria ( Paenibacillus sp. QBH) and cellulase producing bacteria ( Enterococcus sp. N1) was applied for its high degrading efficiency of kelp waste. Serial single factor experiments revealed that temperature, shaking speed and degradation time were the key factors impacting the alginate lyase and filter paper assay activities upon hydrolyzing kelp waste by N1 + QBH combination. Via response surface method optimization, predicted models for the alginate lyase and filter paper assay activities asserted the highest values could be attained at the temperature 34 °C, shaking speed 180 rpm and degradation time 4.5 days. This prediction was verified by a triplicate experiment giving an average alginate lyase activity of 61.2 U mL −1 and filter paper assay activity of 6.12 U mL −1 . Biodegradation of kelp waste by N1 + QBH combination under optimizing conditions remarkably promoted the release of sugars, total phenolic compounds, various minerals and amino acids, generating a nutritious hydrolysate with a total organic matters yield of 56.3 g L −1 , total phenolic compounds yield of 18.3 mg g −1 dry weight and total amino acids concentration of 247.3 mg L −1 . This study highlights that N1 + QBH combination could be a feasible solution for bioconversion of kelp waste to sustainable production of biostimulant.