Insights into the Superior Bioavailability of Biogenic Sulfur from the View of Its Unique Properties: The Key Role of Trace Organic Substances
Wenji Li, Lin Zhu, Chao Pan, Wenda Chen, Dongdong Xu, Da Kang, Leiyan Guo, Qingqing Mei, Ping Zheng, Meng Zhang
Abstract
Elemental sulfur (S 0 ) is widely utilized in environmental pollution control, while its low bioavailability has become a bottleneck for S 0 -based biotechnologies. Biogenic sulfur (bio-S 0 ) has been demonstrated to have superior bioavailability, while little is known about its mechanisms thus far. This study investigated the bioavailability and relevant properties of bio-S 0 based on the denitrifying activity of Thiobacillus denitrificans with chemical sulfur (chem-S 0 ) as the control. It was found that the conversion rate and removal efficiency of nitrate in the bio-S 0 system were 2.23 and 2.04 times those of the chem-S 0 system. Bio-S 0 was not pure orthorhombic sulfur [S: 96.88 ± 0.25% (w/w)]. Trace organic substances detected on the bio-S 0 surface were revealed to contribute to its hydrophilicity, resulting in better dispersibility in the aqueous liquid. In addition, the adhesion force of T. denitrificans on bio-S 0 was 1.54 times that of chem-S 0, endowing a higher bacterial adhesion efficiency on the sulfur particle. The weaker intermolecular binding force due to the low crystallinity of bio-S 0 led to enhanced cellular uptake by attached bacteria. The mechanisms for the superior bioavailability of bio-S 0 were further proposed. This study provides a comprehensive view of the superior bioavailability of bio-S 0 and is beneficial to developing high-quality sulfur resources.