Lipolytic bacteria in the Ottawa river.

Area of Science:

• Environmental microbiology
• Aquatic microbiology
• Bacteriology

Background:

• Brewery Creek, an Ottawa River tributary, was studied for microbial populations during winter.
• Previous research indicated varying microbial loads based on pollution levels in aquatic environments.

Purpose of the Study:

• To isolate and characterize lipolytic bacteria from Brewery Creek.
• To assess the impact of pollution and temperature on lipolytic bacterial populations and their activity.
• To understand seasonal dynamics of dominant bacterial genera.

Main Methods:

• Isolation of lipolytic bacteria from water samples collected at upstream and downstream stations.
• Culturing bacteria on selective media at different temperatures (4°C, 20°C, 30°C).
• Quantification of total and lipolytic bacterial counts.
• Tentative classification of isolates using standard microbiological techniques.

Main Results:

• Lipolytic bacterial counts were 100-fold higher at the polluted downstream station compared to the upstream station.
• Bacterial populations at the downstream station showed evidence of both mesophilic and psychrophilic bacteria.
• Dominant genera identified were Pseudomonas, Acinetobacter-Moraxella, and Aeromonas, with significant seasonal shifts in their relative abundance.
• Lipolysis activity was generally strongest at lower temperatures (≤20°C).

Conclusions:

• Pollution significantly influences the abundance and composition of lipolytic bacteria in aquatic ecosystems.
• Seasonal variations impact the dominance of specific bacterial groups, suggesting adaptation to changing environmental conditions.
• The identified bacterial groups possess diverse temperature optima for growth and lipolytic activity, relevant for understanding nutrient cycling in cold environments.