Presentation Information
[P04-468]Production of Single-Cell Protein from Lactic Acid-Fermented Whey Using Meyerozyma guilliermondii TY-89 without pH Adjustment
○Ai Tanaka1,2, Yukino Kobayashi2, Masatoshi Kubota1, Takanori Nihira1, Satoshi Takesono1, Toshiaki Nakajima3, Toshiya Shigeno4, Masayuki Onodera1,2 (1. Niigata Institute of Technology (Japan), 2. Niigata Prefecture Microbiological Society (Japan), 3. Tsukuba University (Japan), 4. Laboratory of Tsukuba Environmental Microbiology (Japan))
Keywords:
Lactic acid-fermented whey,Single-cell protein (SCP),Meyerozyma guilliermondii TY-89,Dairy waste valorization
[Purpose]
A large portion of whey generated during cheese production is discarded without utilization, and its high BOD increases wastewater treatment costs. Converting whey into microbial protein (single-cell protein, SCP) could reduce environmental burden while providing an alternative protein source to address future shortages. In this study, we focused on a yeast capable of growing under acidic conditions (pH 2–3) and evaluated its ability to grow in whey without pH adjustment.
[Method]
Lactic acid-fermented milk was prepared by adding 400 mL of plain yogurt to 1000 mL of milk, followed by incubation at 37℃ for 7 days. The curd was removed by two rounds of centrifugation, and the supernatant was filtered to obtain lactic acid-fermented whey. Meyerozyma guilliermondii TY-89 (TY-89) was used, and cultivation was conducted at 30℃. For preculture, two loopfuls of TY-89 were inoculated into 10 mL of GPY medium in a 300 mL Erlenmeyer flask and incubated with shaking for 24 h. The preculture was inoculated into 2000 mL Erlenmeyer flasks containing 100, 200, or 300 mL of whey at a ratio of 4 mL per 100 mL of whey, followed by rotary shaking at 200 rpm. Cell biomass was determined as dry cell weight using glass fiber filters (GF/B). Sugars in the whey were analyzed by thin-layer chromatography (TLC) using standard procedures, with glucose, galactose, and lactose (1% each) as references.
[Results]
Cell growth increased over time in all culture volumes, reaching 15.0 g/L, 13.3 g/L, and 12.7 g/L after 96 h in cultures containing 100, 200, and 300 mL of whey, respectively. TLC analysis confirmed that TY-89 assimilated glucose and galactose present in the whey.
[Consideration]
TY-89 exhibited robust growth in lactic acid-fermented whey, achieving biomass concentrations exceeding 12 g/L under all tested conditions. However, increasing the culture volume resulted in a gradual decrease in biomass concentration. This trend is likely due to differences in oxygen transfer efficiency. In shake-flask cultures, oxygen supply depends on the gas–liquid interfacial area and mixing conditions; thus, larger culture volumes reduce the effective surface area for oxygen transfer, leading to oxygen limitation and decreased growth. These findings indicate that glucose and galactose served as the primary carbon sources for TY-89 growth and demonstrate the feasibility of using lactic acid-fermented whey as a substrate for SCP production. This approach highlights the potential for valorizing dairy waste while contributing to sustainable protein production.
[Conclusion]
This study demonstrates that Meyerozyma guilliermondii TY-89 can be cultivated in lactic acid-fermented whey without pH adjustment, achieving high biomass production. The results highlight the potential of this process for sustainable SCP production from dairy waste.
A large portion of whey generated during cheese production is discarded without utilization, and its high BOD increases wastewater treatment costs. Converting whey into microbial protein (single-cell protein, SCP) could reduce environmental burden while providing an alternative protein source to address future shortages. In this study, we focused on a yeast capable of growing under acidic conditions (pH 2–3) and evaluated its ability to grow in whey without pH adjustment.
[Method]
Lactic acid-fermented milk was prepared by adding 400 mL of plain yogurt to 1000 mL of milk, followed by incubation at 37℃ for 7 days. The curd was removed by two rounds of centrifugation, and the supernatant was filtered to obtain lactic acid-fermented whey. Meyerozyma guilliermondii TY-89 (TY-89) was used, and cultivation was conducted at 30℃. For preculture, two loopfuls of TY-89 were inoculated into 10 mL of GPY medium in a 300 mL Erlenmeyer flask and incubated with shaking for 24 h. The preculture was inoculated into 2000 mL Erlenmeyer flasks containing 100, 200, or 300 mL of whey at a ratio of 4 mL per 100 mL of whey, followed by rotary shaking at 200 rpm. Cell biomass was determined as dry cell weight using glass fiber filters (GF/B). Sugars in the whey were analyzed by thin-layer chromatography (TLC) using standard procedures, with glucose, galactose, and lactose (1% each) as references.
[Results]
Cell growth increased over time in all culture volumes, reaching 15.0 g/L, 13.3 g/L, and 12.7 g/L after 96 h in cultures containing 100, 200, and 300 mL of whey, respectively. TLC analysis confirmed that TY-89 assimilated glucose and galactose present in the whey.
[Consideration]
TY-89 exhibited robust growth in lactic acid-fermented whey, achieving biomass concentrations exceeding 12 g/L under all tested conditions. However, increasing the culture volume resulted in a gradual decrease in biomass concentration. This trend is likely due to differences in oxygen transfer efficiency. In shake-flask cultures, oxygen supply depends on the gas–liquid interfacial area and mixing conditions; thus, larger culture volumes reduce the effective surface area for oxygen transfer, leading to oxygen limitation and decreased growth. These findings indicate that glucose and galactose served as the primary carbon sources for TY-89 growth and demonstrate the feasibility of using lactic acid-fermented whey as a substrate for SCP production. This approach highlights the potential for valorizing dairy waste while contributing to sustainable protein production.
[Conclusion]
This study demonstrates that Meyerozyma guilliermondii TY-89 can be cultivated in lactic acid-fermented whey without pH adjustment, achieving high biomass production. The results highlight the potential of this process for sustainable SCP production from dairy waste.
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