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[Purpose/Significance] The paper points out that "building the ecosystem" and "driven by demand" are two keywords for academic libraries to meet the digital scholarship needs of humanities scholars and build digital humanities services. Both of these require us to understand the strategic issues of digital humanities services for academic libraries from the macro perspective, and then explore the feasible path to construct a digital academic ecology from the macro and academic level. [Method/Process] Based on the early accumulation of the subject group and related cases, this paper discusses the necessity and possibility of constructing the ecosystem of digital humanities. [Results/Conclusions] The main conclusions include: (1) emphasizing the respect for objective realities, and regarding the construction of " ecosystem of digital humanities " as the primary goal; (2) clearing up the different types of digital academic needs of humanities scholars and carrying out the type study of academic libraries according to their needs; (3) academic libraries can be divided into leading academic libraries, academic libraries that play a supporting role and those at a basic level, and we should promote different types of academic libraries to perform their duties in the digital academic ecology, to meet different needs of humanities scholars, and to construct the ecosystem of digital humanities.

Metabolic engineering of microbial cell factories for the production of heterologous secondary metabolites implicitly relies on the intensification of intracellular flux directed toward the product of choice. Apart from reactions following peripheral pathways, enzymes of the central carbon metabolism are usually targeted for the enhancement of precursor supply. In Pseudomonas putida , a Gram-negative soil bacterium, central carbon metabolism, i.e., the reactions required for the synthesis of all 12 biomass precursors, was shown to be regulated at the metabolic level and not at the transcriptional level. The bacterium's central carbon metabolism appears to be driven by demand to react rapidly to ever-changing environmental conditions. In contrast, peripheral pathways that are only required for growth under certain conditions are regulated transcriptionally. In this work, we show that this regulation regime can be exploited for metabolic engineering. We tested this driven-by-demand metabolic engineering strategy using rhamnolipid production as an example. Rhamnolipid synthesis relies on two pathways, i.e., fatty acid de novo synthesis and the rhamnose pathway, providing the required precursors hydroxyalkanoyloxy-alkanoic acid (HAA) and activated (dTDP-)rhamnose, respectively. In contrast to single-pathway molecules, rhamnolipid synthesis causes demand for two central carbon metabolism intermediates, i.e., acetyl-CoA for HAA and glucose-6-phosphate for rhamnose synthesis. Following the above-outlined strategy of driven by demand, a synthetic promoter library was developed to identify the optimal expression of the two essential genes ( rhlAB ) for rhamnolipid synthesis. The best rhamnolipid-synthesizing strain had a yield of 40% rhamnolipids on sugar [Cmol RL /Cmol Glc ], which is approximately 55% of the theoretical yield. The rate of rhamnolipid synthesis of this strain was also high. Compared to an exponentially growing wild type, the rhamnose pathway increased its flux by 300%, whereas the flux through de novo fatty acid synthesis increased by 50%. We show that the central carbon metabolism of P. putida is capable of meeting the metabolic demand generated by engineering transcription in peripheral pathways, thereby enabling a significant rerouting of carbon flux toward the product of interest, in this case, rhamnolipids of industrial interest.