Clarifying the essential succession dynamics of interspecies interactions during biofilm development is crucial for the regulation and application of biofilm-based processes. In this study, regular and time-series phylogenetic molecular ecological networks were constructed to investigate ordinary and time-lagged interspecies interactions during biofilm development in a moving bed biofilm reactor. Positive interactions dominated both regular (89.78%) and time-series (77.04%) ecological networks, suggesting that extensive cooperative behaviors facilitated biofilm development. The pronounced directional interactions (72.52%) in the time-series network further indicated that time-lagged interspecies interactions prevailed in the biofilm development process. Specifically, the proportion of directional negative interactions was higher than that of positive interactions, implying that interspecific competition preferred to be time-lagged. The time-series network revealed that module hubs exhibited extensive time-lagged positive interactions with their neighbors, and most of them exhibited altruistic behaviors. Keystone species possessing more positive interactions were positively correlated with biofilm biomass, NO₃⁻-N concentrations, and the removal efficiencies of NH₄⁺-N and chemical oxygen demand. However, keystone species and peripherals that were negatively targeted by their neighbors showed positive correlations with the concentrations of NO₂⁻-N, polysaccharides, and proteins in the soluble microbial products. The data highlight that the time-series network can provide directional microbial interactions along with the biofilm development process, which would help to predict the tendency of community shifts and propose efficient strategies for the regulation of biofilm-based processes.

中文翻译：

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移动床生物膜反应器生物膜发育过程中存在时间滞后的种间相互作用

阐明生物膜发育过程中种间相互作用的基本演替动力学对于基于生物膜的过程的调节和应用至关重要。在这项研究中，构建了规则和时间序列的系统发育分子生态网络，以研究移动床生物膜反应器中生物膜发育过程中的普通和时间滞后的种间相互作用。正相互作用主导了常规（89.78%）和时间序列（77.04%）生态网络，表明广泛的合作行为促进了生物膜的发育。时间序列网络中明显的定向相互作用（72.52%）进一步表明，时间滞后的种间相互作用在生物膜发育过程中占主导地位。具体来说，定向负相互作用的比例高于正相互作用的比例，这意味着种间竞争更倾向于时滞。时间序列网络显示，模块中心与其邻居表现出广泛的时滞积极互动，其中大多数表现出利他行为。具有更多正相互作用的关键物种与生物膜生物量呈正相关，NO₃ ^- -N 浓度、NH ₄ ⁺ -N 和化学需氧量的去除效率。然而，被其邻居负面靶向的关键物种和外围物质与可溶性微生物产物中NO ₂ ^- -N、多糖和蛋白质的浓度呈正相关。数据强调，时间序列网络可以提供定向的微生物相互作用以及生物膜的发展过程，这将有助于预测群落变化的趋势，并提出有效的基于生物膜的过程调节策略。