A functional and applied perspective of Vitreoscilla hemoglobin: from oxygen carriage to biotechnological innovation.

Vitreoscilla hemoglobin (VHb), a homodimeric bacterial hemoglobin, exhibits distinct oxygen-binding properties that enhance cellular respiration and metabolic activity, particularly under hypoxic conditions. This review presents an updated and comprehensive synthesis of VHb-related research, encompassing its molecular structure, redox biochemistry, and transcriptional regulation. Compared with previous reviews, this work integrates recent mechanistic insights-especially those concerning transcription factor interactions, redox-coupled electron transfer, and structural-function relationships elucidated via targeted mutagenesis. In addition to its canonical role in oxygen delivery, VHb has been increasingly utilized in synthetic biology, high-cell-density fermentation, CRISPR-regulated expression platforms, and mammalian systems. Its biotechnological applications extend to enhancing microbial productivity under oxygen limitation, facilitating biocatalysis, and promoting biodegradation. In addition, the review highlights the emerging application of the vgb promoter as a strong regulatory element and summarizes current trends in VHb-related intellectual property and commercial development. VHb also shows promise in next-generation technologies such as environmental remediation and precision agriculture. Future directions should focus on optimizing expression systems, characterizing protein interaction networks, and engineering modular VHb-based components for advanced biosystems.