碱性铝土矿残渣(BR)的生物中和可以通过富含碳水化合物的有机物(例如植物残渣)的发酵分解产生的原位有机酸来实现,这些有机酸是由耐受极端盐碱条件的亲有机物和异养原核生物驱动的。本研究调查了是否可以通过在富含碳水化合物的植物残体中预培养耐受性原核生物来提高它们在土壤微生物菌剂中的恢复能力,从而提高强碱性 BR 的生物中和效率。在为期 2 周的 BR(pH ~ 10.5)微观世界实验中,发现在 BR 与植物残渣(即 SM:甘蔗覆盖物,LH:卢塞恩干草)用土壤微生物接种物预培养。结果表明,10-20% 的初始接种土壤原核特征在预培养植物残体处理中得到恢复。此外,丰富的多样化原核生物在修订后的BR中形成了高度聚集的网络。尽管碱性矿物在 BR 固相中具有缓冲作用,但这些模块积极推动了 C 和 N 矿化并持续降低 0.8-2.0 个单位的 pH 值。相比之下,在生长培养基中培养的土壤微生物接种物失去了土壤接种物中 99% 以上的原始原核特征,导致处理过的 BR 仅降低 0.2-0.7 个单位的 pH 值。因此,在植物残体中预培养土壤接种物作为处理 BR 以实现有效生物中和的整体系统将是优选的。结果表明,10-20% 的初始接种土壤原核特征在预培养植物残体处理中得到恢复。此外,丰富的多样化原核生物在修订后的BR中形成了高度聚集的网络。尽管碱性矿物在 BR 固相中具有缓冲作用,但这些模块积极推动了 C 和 N 矿化并持续降低 0.8-2.0 个单位的 pH 值。相比之下,在生长培养基中培养的土壤微生物接种物失去了土壤接种物中 99% 以上的原始原核特征,导致处理过的 BR 仅降低 0.2-0.7 个单位的 pH 值。因此,在植物残体中预培养土壤接种物作为处理 BR 以实现有效生物中和的整体系统将是优选的。结果表明,10-20% 的初始接种土壤原核特征在预培养植物残体处理中得到恢复。此外,丰富的多样化原核生物在修订后的BR中形成了高度聚集的网络。尽管碱性矿物在 BR 固相中具有缓冲作用,但这些模块积极推动了 C 和 N 矿化并持续降低 0.8-2.0 个单位的 pH 值。相比之下,在生长培养基中培养的土壤微生物接种物失去了土壤接种物中 99% 以上的原始原核特征,导致处理过的 BR 仅降低 0.2-0.7 个单位的 pH 值。因此,在植物残体中预培养土壤接种物作为处理 BR 以实现有效生物中和的整体系统将是优选的。
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Pre-culturing soil microbial inoculum in plant residues enhanced the resilience of tolerant bacteria and bioneutralization efficacy in alkaline bauxite residues
Bioneutralization of alkaline bauxite residues (BR) may be achieved through in situ organic acids produced from fermentative decomposition of carbohydrates-rich organic matters (e.g., plant residues), which are driven by organophilic and heterotrophic prokaryotes tolerant of extremely saline and alkaline conditions. The present study investigated if the resilience of tolerant prokaryotes in soil microbial inoculums could be improved by pre-culturing them in carbohydrate-rich plant residues, leading to enhanced bioneutralization efficacy in strongly alkaline BR. In a 2-week microcosm experiment with BR (pH ~ 10.5), it was found that the resilience of prokaryotic communities and their functional modules and bioneutralization efficacy were significantly boosted in BR admixed with plant residues (i.e., SM: sugarcane mulch, LH: Lucerne hay) pre-cultured with soil microbial inoculum. The results showed that 10–20% of the initially inoculated soil prokaryotic features were recovered in treatments with pre-cultured plant residues. Besides, the enriched diverse prokaryotes formed highly clustered networks in the amended BR. These modules actively drove C and N mineralization and sustained 0.8–2.0 units of pH reduction, despite the buffering effects of alkaline minerals in BR solid phase. In contrast, soil microbial inoculation cultured in the growth medium lost >99% of the original prokaryotic features in soil inoculums, resulting in merely 0.2–0.7 unit pH reduction in the treated BR. Therefore, pre-culturing soil inoculum in plant residues would be preferred as an integral system to treat BR for effective bioneutralization.