Novel insights into pretreatment improving the cooperation of adhesive and planktonic microbes in anaerobic digestion.

Abstract

Interactions between adhesive and planktonic microbes critically regulate anaerobic digestion (AD) of lignocellulosic biomass, yet how pretreatment alters these microbial dynamics and consequently influence methane output remain unclear. This study employed HCl and NaOH as representative chemical pretreatments to investigate their effects on the dynamics of adhesive versus planktonic microbes during corn stalk (CS) digestion. Results showed 2 % NaOH-pretreated CS reached the highest methane yield (380.9 mL/g VS), 32.7 % increase than HCl pretreatment. Following NaOH pretreatment, the abundance of adhesive Proteinophilum sp. S20 increased by 61.7 %-280.4 % than HCl pretreatment. Moreover, the planktonic populations of acidogenic Dysgononadaceae bacteria zrk40 and Fermentimonas caenicola was also significantly increased. Additionally, NaOH pretreatment notably boosted the adhesive abundance of Methanocollius chikugoensis by 62.0 %-306.0 % relative to HCl pretreatment and favored hydrogenotrophic metagenesis process. These findings deepen theoretical understanding of microbial interactions and offer new insights into developing pretreatments enhancing microbial cooperation and methane yield in AD.