酸热水解制备蓝藻基植物激励素条件优化及产物特征

Optimization and product characteristics of cyanobacteria-based plant growth stimulants by acid and thermal hydrolysis

以蓝藻作为原材料,对蓝藻进行酸热水解,分析蓝藻酸热水解最优条件,并通过内梅罗指数、地累积指数法、潜在生态指数法和人体暴露健康风险评价验证各条件制备的蓝藻基植物激励素施用于土壤的安全性.结果显示,采用2%草酸进行水解可利用草酸对重金属的络合作用以降低蓝藻基植物激励素的环境风险,同时为保证蓝藻的水解效果,耦合硫酸调节pH值至0.8,水解时间保持24h是最优酸热水解条件.各条件制备的蓝藻基植物激励素内梅罗指数、地累积指数、潜在生态指数分别处于无风险、无污染和低风险水平,对人体致癌风险和非致癌风险均低于安全阈值10^(-6)和1.利用半连续流酸热水解体系可提升蓝藻基植物激励素中有益物质的浓度,发现经过3~4个周期的水解富集,植物激励素中N、P、K等营养物质稳定在3942、290.45和421.7mg/kg.2-(5H)-呋喃酮和吡咯类物质等生物刺激素类物质在植物激励素中不断富集后达到29.5646和11.261mg/kg,均可发挥促进植物生长和抑制病菌的作用.同时,生物碱类、酚类物质等化感物质在水解过程中被破坏,有效减轻了其对植物生长的抑制作用.

This study utilized cyanobacteria as a raw material,subjecting it to acid-thermal hydrolysis.The optimal hydrolysis conditions for cyanobacteria were analyzed,and the safety of applying cyanobacteria-based plant stimulants to soil was evaluated using Pij、Igeo、RI and human exposure health risk assessment.Results demonstrated that using 2%oxalic acid for hydrolysis,exploiting the chelation effect of oxalic acid on heavy metals,and further adjusting the pH to 0.8 with sulfuric acid while maintaining a 24-hour hydrolysis constituted the optimal acid-thermal hydrolysis conditions to minimize environmental risks associated with cyanobacteria-based plant stimulants.The Pij、Igeo、RI of cyanobacteria-based plant stimulants prepared under various conditions indicated negligible risks,absence of pollution,and low-risk levels,respectively.Moreover,the calculated human carcinogenic and non-carcinogenic risks associated with plant stimulants were found to be below the safety thresholds of 10^(-6) and 1.In addition,using a semi-continuous acid-thermal hydrolysis system to enhance the concentration of beneficial substances in cyanobacteria-based plant growth stimulants,it was observed that after 3~4cycles of hydrolysis enrichment,the levels of nutrients(N,P,and K)in the plant growth stimulants stabilized at 3942,290.45,and 421.7mg/kg,respectively.Furthermore,2-(5H)-furanone and pyrrole compounds,classified as bio-stimulants,continued to accumulate in the plant growth stimulants,reaching levels of 29.5646 and 11.261mg/kg,respectively.These substances can effectively promote plant growth and inhibit pathogens.Moreover,alkaloids and phenolic compounds,considered as allelopathic substances,were degraded during hydrolysis,and subsequently alleviating the inhibitory effects on plant growth.