GRAM POSITIVE BACTERIA

The contamination of water sources by untreated wastewater poses a serious public health risk due to the spread of pathogenic bacteria, particularly Gram-positive species. This study examined the microbiological properties of wastewater collected from commercial laundry shops in Benin City, Edo State, Nigeria. The research focused on enumerating total heterotrophic bacteria, isolating Gram-positive bacteria, and identifying their species based on morphological and biochemical characteristics. A total of eight (8) wastewater samples were collected in duplicates from two commercial laundry shops, with the samples divided into two categories: wastewater from washing and wastewater from rinsing. Microbial enumeration was performed using the spread plate technique on nutrient agar, while Mannitol salt agar was used for selective screening of Gram-positive bacteria. The bacterial isolates were characterized based on their morphological and biochemical properties using standard microbiological methods. Results revealed that the total heterotrophic bacterial counts were highest in the laundry washing wastewater samples, with values ranging from 102±2.3 × 10⁶ to 81±0.9 × 10⁶ CFU/mL. In contrast, significantly lower bacterial counts were observed in the rinsing wastewater samples, with counts ranging from 48±1.8 × 10⁶ to 25±2.4 × 10⁶ CFU/mL. Additionally, the bacterial counts varied by location, with Laundry Shop 1 recording 68±1.4 × 10⁶ CFU/mL and Laundry Shop 2 showing slightly lower counts at 57±1.6 × 10⁶ CFU/mL. The microbiological assessment of laundry wastewater revealed the presence of diverse bacterial species, with a total of 17 isolates identified and characterized. Staphylococcus aureus was the most prevalent isolate, accounting for 52.9% (9/17) of the total, followed by Staphylococcus spp. (41.2%) and Micrococcus spp. (5.9%). These findings highlight the potential health and environmental risks associated with untreated laundry wastewater, particularly due to the dominance of pathogenic and opportunistic bacteria. The study emphasizes the need for effective wastewater management practices in commercial laundry facilities to mitigate the spread of microbial contaminants. Future research could focus on advanced treatment technologies and their ability to reduce bacterial load in laundry effluent.