Data_Sheet_1_Understanding the Shift in the Microbiome of Composts That Are Optimized for a Better Fit-for-Purpose in Growing Media.PDF

Three characteristics are considered key for optimal use of composts in growing media: maturity, pH and organic matter content. Maturation is a critical step in the processing of composts contributing to compost quality. Blending of composts with chopped heath biomass, sieving out the larger fraction of composts and acidification of composts by adding elemental sulfur may be used either to increase organic matter content or to reduce pH for a better fit in growing media. While several studies have shown the effectiveness of these treatments to improve the use of composts in growing media, the effect of these treatments on the compost microbiome has merely been assessed before. In the present study, five immature composts were allowed to mature, and were subsequently acidified, blended or sieved. Bacterial and fungal communities of the composts were characterized and quantified using 16S rRNA and ITS2 gene metabarcoding and phospholipid fatty acid analysis. Metabolic biodiversity and activity were analyzed using Biolog EcoPlates. Compost batch was shown to be more important than maturation or optimization treatments to determine the compost microbiome. Compost maturation increased microbial diversity and favored beneficial microorganisms, which may be positive for the use of composts in growing media. Blending of composts increased microbial diversity, metabolic diversity, and metabolic activity, which may have a positive effect in growing media. Blending may be used to modify the microbiome to a certain degree in order to optimize microbiological characteristics. Acidification caused a decrease in bacterial diversity and microbial activity, which may be negative for the use in growing media, although the changes are limited. Sieving had limited effect on the microbiome of composts. Because of the limited effect on the microbiome, sieving of composts may be used flexible to improve (bio)chemical characteristics. This is the first study to assess the effects of maturation and optimization treatments to either increase organic matter content or lower pH in composts on the compost microbiome.

为实现堆肥在栽培基质（growing media）中的最优应用，需重点考量三大核心特性：腐熟度（maturity）、pH值与有机质含量。腐熟处理是堆肥加工过程中的关键环节，直接决定堆肥品质。通过将堆肥与切碎的石楠生物质（chopped heath biomass）混合、筛分去除堆肥中的大粒径组分，以及通过添加单质硫（elemental sulfur）实现堆肥酸化，这些手段均可用于提升堆肥有机质含量或降低pH值，使其更适配栽培基质的应用要求。尽管已有多项研究证实上述处理可优化堆肥在栽培基质中的应用效果，但此前针对这些处理对堆肥微生物组（microbiome）的影响仅开展过少量评估。本研究选取5份未腐熟堆肥，先进行腐熟处理，随后分别开展酸化、混合或筛分操作。本研究采用16S rRNA与ITS2基因元条形码（metabarcoding）测序、磷脂脂肪酸（phospholipid fatty acid）分析技术，对堆肥中的细菌与真菌群落进行表征与定量分析；同时采用Biolog EcoPlates技术分析堆肥的代谢生物多样性与代谢活性。研究结果显示，相较于腐熟处理与优化处理，堆肥批次对堆肥微生物组的影响更为显著。堆肥腐熟处理可提升微生物多样性，并促进有益微生物的增殖，这对堆肥在栽培基质中的应用具有积极意义。堆肥混合处理可提升微生物多样性、代谢多样性与代谢活性，有助于优化其在栽培基质中的应用效果；混合处理可在一定程度上调控堆肥微生物组，以优化其微生物学特性。酸化处理会导致细菌多样性与微生物活性下降，尽管这种影响较为有限，但可能对堆肥在栽培基质中的应用产生不利影响。筛分处理对堆肥微生物组的影响较为有限，鉴于此，可灵活采用该手段以优化堆肥的（生物）化学特性。本研究首次针对可提升堆肥有机质含量或降低pH值的腐熟与优化处理，探究其对堆肥微生物组的影响。