Malaysian Virgin Soil Extracts as Natural Growth Enhancer for Targeted Green Microalgae Species

Featured Application The virgin soil extracts have a huge potential as growth enhancers for the mass cultivation of microalgae. The microalgae-based industries are trending upwards, particularly as the feed ingredient for aquaculture. Therefore, a sustainable and reasonably priced source of nutrients to support the mass cultivation of microalgae is in great demand. The present study explored the feasibility of using extracts from virgin soil as natural growth-promoting nutrients for the cultivation of Nannochloropsis oculata, Nannochloropsis oceanica, and Chlorella sorokiniana. The extracts were obtained from Bera Lake Forest using five different treatment methods. The greatest retrieval of dissolved organic carbon, total dissolved nitrogen, and total dissolved phosphorus were observed with the autoclave treatment method at 121 degrees C twice, yielding a respective concentration of 336.56 mg/L, 13.40 mg/L, and 0.14 mg/L, respectively. The highest growth was recorded with Nannochloropsis oculata resulting in an optical density of 0.488 +/- 0.009 (x10(3) cell mL(-1)), exhibiting 43% and 44% enhanced growth in comparison to Nannochloropsis oceanica and Chlorella sorokiniana, respectively. The specific growth rate (0.114 (a) +/- 0.007 d(-1)) was the highest for Nannochloropsis oculata when the 24 h-extraction method was used, whereas the utilization of the autoclave 121 degrees C twice treatment method contributed to the highest specific growth of Nannochloropsis ocenica (0.069 (a) +/- 0.003 d(-1)) and Chlorella sorokiniana (0.080 (a) +/- 0.001 d(-1)). Collectively, these findings suggested that the addition of soil extracts which is sustainable and inexpensive promoted the growth of microalgae compared to the control system. A further study investigating the optimum culture conditions for enhanced microalgae growth will be carried out for the mass production of microalgae biomass.

Automated summary

This study explored the feasibility of using extracts from virgin soil as natural growth-promoting nutrients for microalgae cultivation. The results showed that the addition of sustainable and inexpensive soil extracts promoted the growth of microalgae, and further research on optimizing the culture conditions for enhanced microalgae growth will be conducted for mass production.