Effects of various soil extract fraction types on the growth of marine microalgae

Emi Fazlina Hashim, . and Komatsu, Kazuhiro and Imai, Akio and Onouchi, Hidemi and Wan Muhammad Ikram Wan Mohd Zamri, . and Nor Suhaila Yaacob, . and Ohtake, Masahiro and Sekine, Mutsumi and Toda, Tatsuki (2023) Effects of various soil extract fraction types on the growth of marine microalgae. Journal of Sustainability Science and Management (Malaysia), 18 (7). pp. 166-184. ISSN 2672-7226

Organic matter from terrestrial and aquatic sources plays a major role in microalgae cultivation; however, its complementary effects on microalgal growth are almost unknown to date. In this study, we investigated the effects of dissolved organic matter from forest soil and its fractions on naturally isolated marine microalgae: Green microalgae (Chlorella sorokiniana and Oocystis heteromucosa) and diatom (Thalassiosira weissflogii) from Malaysia. The soil was extracted with ultrapure water at two different temperatures: 105°C and 121°C. These two soil extracts were fractionated into humic, nonhumic, low-molecular-size, and high-molecular-size fractions. Microalgal cultivation was conducted using microplates that were added with Conway medium, soil extracts and their fractions. Results showed higher concentrations of all tested chemical elements in soil extracts from 121°C extraction than 105°C. Both specific growth rates of C. sorokiniana and T. weissflogii were found to be around 20% higher in soil extracts at 105°C than in the control. Simultaneously, the humic and low-molecular-size fractions were found to have improved growth rates of 11-17% and 15-31% respectively from their soil extracts at 105°C. The specific growth rate of O. heteromucosa only increased marginally by 7% when compared with the control and with soil extracts at 121°C. The humic and lowmolecular-size fractions increased around 10-37% relative to these soil extracts. The humic and low-molecular-size fractions were consistently associated with greater growthenhancing effects; meanwhile, others were less effective or ineffective.

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Abstract

Organic matter from terrestrial and aquatic sources plays a major role in microalgae cultivation; however, its complementary effects on microalgal growth are almost unknown to date. In this study, we investigated the effects of dissolved organic matter from forest soil and its fractions on naturally isolated marine microalgae: Green microalgae (Chlorella sorokiniana and Oocystis heteromucosa) and diatom (Thalassiosira weissflogii) from Malaysia. The soil was extracted with ultrapure water at two different temperatures: 105°C and 121°C. These two soil extracts were fractionated into humic, nonhumic, low-molecular-size, and high-molecular-size fractions. Microalgal cultivation was conducted using microplates that were added with Conway medium, soil extracts and their fractions. Results showed higher concentrations of all tested chemical elements in soil extracts from 121°C extraction than 105°C. Both specific growth rates of C. sorokiniana and T. weissflogii were found to be around 20% higher in soil extracts at 105°C than in the control. Simultaneously, the humic and low-molecular-size fractions were found to have improved growth rates of 11-17% and 15-31% respectively from their soil extracts at 105°C. The specific growth rate of O. heteromucosa only increased marginally by 7% when compared with the control and with soil extracts at 121°C. The humic and lowmolecular-size fractions increased around 10-37% relative to these soil extracts. The humic and low-molecular-size fractions were consistently associated with greater growthenhancing effects; meanwhile, others were less effective or ineffective.

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Item Type:	Article
AGROVOC Term:	microalgae
AGROVOC Term:	phytoplankton
AGROVOC Term:	soil chemistry
AGROVOC Term:	nutrient availability
AGROVOC Term:	marine ecology
AGROVOC Term:	sampling
AGROVOC Term:	experimental design
AGROVOC Term:	data analysis
AGROVOC Term:	organic matter
AGROVOC Term:	environmental control
Geographical Term:	Malaysia
Depositing User:	Nor Hasnita Abdul Samat
Date Deposited:	23 Nov 2025 05:19
Last Modified:	23 Nov 2025 05:19
URI:	http://webagris.upm.edu.my/id/eprint/1582

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