Industrial penicillin production with the filamentous fungus Penicillium chrysogenum is based on an unprecedented effort in microbial strain improvement. To gain more insight into penicillin synthesis, we sequenced the 32.19 Mb genome of P. chrysogenum Wisconsin54-1255 and identified numerous genes responsible for key steps in penicillin production. DNA microarrays were used to compare the transcriptomes of the sequenced strain and a penicillinG high-producing strain, grown in the presence and absence of the side-chain precursor phenylacetic acid. Transcription of genes involved in biosynthesis of valine, cysteine and α-aminoadipic acid—precursors for penicillin biosynthesis—as well as of genes encoding microbody proteins, was increased in the high-producing strain. Some gene products were shown to be directly controlling β-lactam output. Many key cellular transport processes involving penicillins and intermediates remain to be characterized at the molecular level. Genes predicted to encode transporters were strongly overrepresented among the genes transcriptionally upregulated under conditions that stimulate penicillinG production, illustrating potential for future genomics-driven metabolic engineering.

Significance: Statins are successful widely used drugs that decrease the risk of coronary heart disease and strokes by lowering cholesterol levels. They selectively inhibit the key regulatory enzyme of the cholesterol synthesis pathway, thus lowering levels of plasma LDL (bad) cholesterol. Pravastatin is one of the leading and most effective statins, derived from the natural product compactin. However, pravastatin production involves a costly dual-step fermentation and biotransformation process. Here we present a single-step fermentative method for production of the active drug pravastatin. Reprogramming of the antibiotics-producing fungus Penicillium chrysogenum , with discovery and engineering of an enzyme involved in the hydroxylation of compactin, enables high level fermentation of the correct form of pravastatin to facilitate efficient industrial-scale statin drug production.

Background: Since the discovery of the antibacterial activity of penicillin by Fleming 80 years ago, improvements of penicillin titer were essentially achieved by classical strain improvement through mutagenesis and screening. The recent sequencing of Penicillium chrysogenum strain Wisconsin1255-54 and the availability of genomics tools such as DNA-microarray offer new perspective. Results: In studies on β-lactam production by P. chrysogenum, addition and omission of a side-chain precursor is commonly used to generate producing and non-producing scenarios. To dissect effects of penicillinG production and of its side-chain precursor phenylacetic acid (PAA), a derivative of a penicillinG high-producing strain without a functional penicillin-biosynthesis gene cluster was constructed. In glucose-limited chemostat cultures of the high-producing and cluster-free strains, PAA addition caused a small reduction of the biomass yield, consistent with PAA acting as a weak-organic-acid uncoupler. Microarray-based analysis on chemostat cultures of the high-producing and cluster-free strains, grown in the presence and absence of PAA, showed that: (i) Absence of a penicillin gene cluster resulted in transcriptional upregulation of a gene cluster putatively involved in production of the secondary metabolite aristolochene and its derivatives, (ii) The homogentisate pathway for PAA catabolism is strongly transcriptionally upregulated in PAA-supplemented cultures (iii) Several genes involved in nitrogen and sulfur metabolism were transcriptionally upregulated under penicillinG producing conditions only, suggesting a drain of amino-acid precursor pools. Furthermore, the number of candidate genes for penicillin transporters was strongly reduced, thus enabling a focusing of functional analysis studies. Conclusion: This study demonstrates the usefulness of combinatorial transcriptome analysis in chemostat cultures to dissect effects of biological and process parameters on gene expression regulation. This study provides for the first time clear-cut target genes for metabolic engineering, beyond the three genes of the β-lactam pathway.

Nowadays, a growing offering of plant-based meat alternatives is available in the food market. Technologically, these products are produced through high-moisture shear technology. Process settings and material composition have a significant impact on the physicochemical characteristics of the final products. Throughout the process, the unfolded protein chains may be reduced, or associate in larger structures, creating rearrangement and cross-linking during the cooling stage. Generally, soy and pea proteins are the most used ingredients in plant-based meat analogues. Nevertheless, these proteins have shown poorer results with respect to the typical fibrousness and juiciness found in real meat. To address this limitation, wheat gluten is often incorporated into the formulations. This literature review highlights the key role of wheat gluten in creating products with higher anisotropy. The generation of new disulfide bonds after the addition of wheat gluten is critical to achieve the sought-after fibrous texture, whereas its incompatibility with the other protein phase present in the system is critical for the structuring process. However, allergenicity problems related to wheat gluten require alternatives, hence an evaluation of underutilized plant-based proteins has been carried out to identify those that potentially can imitate wheat gluten behavior during high-moisture shear processing.

To increase the appeal of plant protein–based meat analogs, further progress needs to be made in their sensory perception. Given the limited number of studies on meat analogs, this review focuses on structure, oral processing, and sensory perception of meat and subsequently translates the insights to meat analogs. An extensive number of publications has built the current understanding of meat mechanical and structural properties, but inconsistencies concerning terminology and methodology execution as well as the wide variety in terms of natural origin limit solid conclusions about the control parameters for oral processing and sensory perception. Consumer-relevant textural aspects such as tenderness and juiciness are not directly correlated to single structural features but depend on an interplay of multiple factors and thus require a holistic approach. We discuss the differences in mastication and disintegration of meat and meat analogs and provide an outlook toward converting skeptical consumers into returning customers.