Cheese whey wastewater-derived Chlorella biomass promotes growth and β-galactosidase activity of Pediococcus sp. isolated from Gundurk

In the world of food production, waste is often an unavoidable byproduct, but for scientists, it can be a hidden resource. One such waste product is cheese whey, the liquid left over after milk is turned into cheese. While rich in nutrients like sugar and protein, this liquid is difficult to dispose of because it can deplete oxygen in waterways if released untreated. To solve this, researchers look to nature's tiny recyclers: microalgae. These are microscopic, plant-like organisms that use sunlight to grow, but they can also feast on the organic nutrients found in waste streams. When these algae grow, they turn waste into a solid, nutrient-dense biomass. This biomass is not just waste treatment; it is a potential food ingredient packed with proteins and fats. On the other side of the equation are lactic acid bacteria, the workhorses behind fermented foods like yogurt and sauerkraut. These bacteria are essential for human health and food preservation, but they require specific conditions to thrive and produce beneficial enzymes. The question driving this research was whether the algae grown on waste could actually help these bacteria do their job better, creating a cycle where waste becomes a tool for making healthier food.

A team of researchers at the Research Institute for Bioscience and Biotechnology in Nepal set out to test this idea using two specific types of local microorganisms. First, they collected water from a freshwater pond in Banepa to find a wild strain of Chlorella, a common type of green microalgae. They also gathered samples of Gundurk, a traditional fermented vegetable dish made from mustard leaves, to isolate a specific strain of lactic acid bacteria called Pediococcus. The researchers then created two different environments for the algae to grow in. One was a standard laboratory nutrient solution, and the other was a mixture of the cheese whey wastewater and water. They allowed the algae to grow for eight days in both environments. The results showed that the algae grew just as well in the cheese whey as they did in the standard lab solution. In fact, by the end of the experiment, the algae in the cheese whey produced a slightly higher number of cells, reaching a density of 17.3 million cells per milliliter, compared to 15.9 million in the standard solution. More importantly, the algae grown in the waste produced significantly more solid material, yielding 1.40 grams of dry biomass per liter, whereas the standard solution only produced 0.30 grams.

The researchers then examined what was inside these algae cells to see if the waste changed their composition. Using a technique that measures how light bounces off molecules, they found that the algae grown in cheese whey had a different chemical makeup than those grown in the lab. Specifically, the waste-grown algae contained more lipids, which are fats and oils, while the lab-grown algae appeared to have a stronger protein signature. This suggests that the nutrients in the cheese whey, such as lactose and other organic compounds, pushed the algae to store more energy in the form of fats. The team then took this dried algae biomass and added it to the food medium for the Pediococcus bacteria. They wanted to see if feeding the bacteria this algae would help them grow faster or work harder. The results were clear: adding the algae biomass helped the bacteria multiply more quickly during their active growth phase. The bacteria grew significantly better in the presence of the algae than they did without it, particularly after 18 to 24 hours of growth.

Beyond just helping the bacteria grow, the algae also boosted a specific function that is highly valuable for human health: the ability to break down lactose. The Pediococcus bacteria naturally produce an enzyme called beta-galactosidase, which helps digest the sugar found in milk. This is crucial because a large portion of the adult population cannot digest lactose properly. When the researchers measured the activity of this enzyme, they found that the bacteria fed with algae produced much more of it than those in a standard diet. The bacteria fed with algae grown in the standard lab solution produced an enzyme activity level of 49.33 units, while those fed with algae grown in the cheese whey produced 38.82 units. Both of these numbers were significantly higher than the 18.34 units produced by the bacteria in the control group with no algae. This indicates that the algae biomass acts as a powerful booster for the bacteria's enzymatic performance, even though the algae grown in the waste produced slightly less enzyme activity than the algae grown in the lab.

The study concludes that this approach offers a dual benefit for the environment and food science. By using cheese whey to grow algae, the researchers demonstrated a way to clean up a problematic waste stream while simultaneously creating a high-value biomass. This biomass, in turn, serves as a functional food additive that enhances the performance of beneficial bacteria. The findings suggest that wild microorganisms from local environments, such as freshwater ponds and traditional fermented foods, can be combined into a unified system. This system not only recovers nutrients from dairy waste but also generates a product that can improve the quality of fermented foods and potentially aid in the digestion of dairy for those who are lactose intolerant. While the process showed that the algae grown in waste had a slightly different effect on enzyme production compared to lab-grown algae, the overall outcome confirms that waste-derived biomass is a viable and effective tool for supporting the growth and function of beneficial bacteria.