Seasonal changes in bacterial growth in laboratory settings may be atributed to the redox potential of the air, likely due to changing ozone concentrations. I'm guessing there is much ozone in the air in India right now, because of a lot of sunshine during this time of year, which oxidizes some components of the medium. You can try adding some reducing agents to the medium like L-Cysteine·HCl, Na2SO3, Ascorbic acid or Sodium pyruvate and see if this helps.

Winter conditions can influence the production of pyocyanin, a blue-green pigment produced by Pseudomonas aeruginosa and other related bacteria. Pyocyanin is known to be involved in various physiological processes, including the bacterium's response to environmental stresses. While the production of pyocyanin is influenced by various factors, including temperature, oxygen levels, and the availability of nutrients, winter conditions (which typically involve lower temperatures) can have a complex impact:

1. Pyocyanin Production and Temperature:

P. aeruginosa generally produces pyocyanin in response to certain stresses, such as nutrient limitation and environmental cues like low oxygen. While colder temperatures (such as those associated with winter) could reduce the overall metabolic rate of bacteria, they may also enhance the production of pyocyanin in some strains, as a stress response to the harsh environment.

However, in cold temperatures, the enzymatic pathways involved in pyocyanin synthesis could be less efficient or inhibited, leading to reduced pigment production in some cases. The response can vary depending on the strain of P. aeruginosa and the specific environmental conditions.

2. Impact on Biofilm Formation Assays:

Biofilm formation by P. aeruginosa is also temperature-sensitive. Colder temperatures may somewhat hinder biofilm formation, as the bacteria’s growth and metabolic activity are reduced.

Pyocyanin production and biofilm formation are often linked; pyocyanin can influence biofilm structure and its resistance to antimicrobial agents. If pyocyanin levels are altered due to winter conditions, it might indirectly affect the biofilm's stability or resistance. For example, some studies suggest that pyocyanin plays a role in biofilm maturation and may impact its resistance to antibiotics or other stresses.

In biofilm-related assays, lower temperatures or changes in pyocyanin levels could lead to variability in the results. Specifically, if pyocyanin production is suppressed or enhanced, it could interfere with the expected outcomes of assays that depend on both biofilm formation and pigment production.