Humin: No longer inactive natural organic matter

Area of Science:

• Environmental Science
• Microbiology
• Biochemistry

Background:

• Humin (HM) is an insoluble fraction of humic substances (HSs).
• HM was discovered to function as an extracellular electron mediator (EEM) in 2012.
• EEM function of HM is crucial for microbial energy networks and bioremediation.

Purpose of the Study:

• To provide a holistic overview of HM's EEM function.
• To summarize properties, applications, and redox-active structures of HM as an EEM.
• To explore HM-microbial cell interactions and suggest future research directions.

Main Methods:

• Literature review and synthesis of existing studies on HM as an EEM.
• Analysis of properties, applications, and mechanisms of HM's EEM function.
• Discussion of HM-microbial interactions and future research scopes.

Main Results:

• HM functions as an effective EEM, supporting microbial energy transfer.
• HM demonstrates potential for in situ bioremediation of environmental pollutants.
• Recent studies highlight HM's application in anaerobic microbial cultures.

Conclusions:

• HM's EEM function is vital for understanding microbial ecosystems and environmental applications.
• Further research is needed to fully elucidate HM's properties, interactions, and optimize its bioremediation potential.