Biosorption of copper by wine-relevant lactobacilli

Area of Science:

• Enology
• Environmental Microbiology
• Biotechnology

Background:

• Copper contamination in wine and must is a significant issue, often arising from fungicide use or winemaking processes.
• Current methods for reducing excess copper in wine are limited in practicality and safety.
• Biosorption presents a potential eco-friendly alternative for heavy metal remediation in beverages.

Purpose of the Study:

• To investigate the efficacy of wine-relevant Lactobacillus species in biosorbing copper.
• To evaluate the influence of environmental factors, such as pH, on copper binding by these bacteria.
• To determine the copper removal potential in different matrices like deionized water, must, wine, and grape juice.

Main Methods:

• Screening of eight wine-relevant Lactobacillus species for copper biosorption.
• Testing both living and heat-inactivated bacterial cells for copper adsorption.
• Measuring copper binding capacity at varying pH levels.
• Assessing copper removal efficiency in deionized water, grape must, wine, and grape juice.

Main Results:

• All tested Lactobacillus species demonstrated significant copper adsorption capabilities.
• Copper binding capacity was positively correlated with increasing pH.
• Lactobacillus buchneri DSM 20057 exhibited the highest binding capacity (46.17 μg Cu/mg cell in deionized water).
• Copper removal was less effective in must, wine, and grape juice due to factors beyond pH, including cations, organic acids, and phenolics.

Conclusions:

• Wine-associated Lactobacillus species, particularly L. buchneri, are effective biosorbents for copper.
• Biosorption is influenced by environmental factors, with higher pH enhancing copper removal.
• This microbial approach can significantly reduce critical copper concentrations in wine, offering a practical detoxification strategy.