Enumeration, characterization and identification of bacteria in soils of selected waste dumpsites in Rivers State, Nigeria

Rapid population growth and industrialization have led to increased waste generation, while effective wastemanagement remains a major challenge in Nigeria, where solid wastes are often indiscriminately disposedof. This study investigated the diversity and abundance of bacteria in soils from selected solid waste dumpsites in Rivers State, Nigeria. Soil samples were collected monthly from three dump sites and three controllocations between May 2023 and April 2024. Samples were analyzed using standard microbiologicaltechniques and cultured on Nutrient Agar, MacConkey Agar, Starch Casein Agar, Salmonella–Shigella Agar,Thiosulfate Citrate Bile Salts Sucrose (TCBS) Agar, and Mannitol Salt Agar. Purified isolates were identifiedusing morphological and biochemical characterization. Mean bacterial counts ranged as follows: totalheterotrophic bacteria (THB), 2.9 ± 1.6 - 8.3 ± 2.2 × 105 cfu/g; total coliforms, 4.1 ± 1.2 - 12.5 ± 2.4 × 103cfu/g; total actinomycetes, 0.6 ± 0.3 - 3.3 ± 1.4 × 103 cfu/g; total Staphylococcus, 3.6 ± 2.1 - 16.1 ± 1.4 × 103cfu/g; total Salmonella, 0.1 ± 0.1 - 2.1 ± 0.3 × 102 cfu/g; total Shigella, 0.0 ± 0.0 - 0.9 ± 0.1 × 102 cfu/g; andtotal Vibrio, 0.0 ± 0.0 - 5.5 ± 0.5 × 102 cfu/g. No significant difference (p > 0.05) was observed in THBpopulations among the study locations, whereas other bacterial groups showed significant variations (p <0.05) in some locations. Identified bacterial genera included Rhizobacter, Enterobacter, Citrobacter,Cronobacter, Kluyvera, Paraburkholderia, Serratia, Ralstonia, Vibrio, Aeromonas, Erwinia, Leclercia,Chryseomonas, Klebsiella, Pseudomonas, Salmonella, Shigella, Bacillus, Paenibacillus, Staphylococcus,Enterococcus, Salinococcus, Corynebacterium, Actinomyces, Rathayibacter, Microbacterium,Zhihengliuella, Sinomonas, Nesterenkonia, and Escherichia coli. THB counts were highest at the Boskeldumpsite, followed by the Aluu dumpsite, and lowest at the Elijiji dumpsite. Staphylococcus spp. were themost prevalent isolates across the sites. The high bacterial load and diversity observed indicate that solidwaste dumpsites may serve as reservoirs of potentially pathogenic microorganisms, posing environmentaland public health risks to waste workers and nearby residents. These findings highlight the need forimproved waste management practices and the siting of dumpsites at safe distances from residential areasto minimize potential health hazards.