Palm oil mill effluent (POME) contains large quantities of organic matter in the form of total suspended solids (TSS), volatile suspended solids (VSS), total solids (TS), oil and grease (O & G) that increase biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of POME if left untreated. The main aim of the present study was to investigate the ability of bacterial strains either pure (individually) or mixed (combinations), to degrade and metabolize organic load from palm oil mill effluent. Sequencing of the 16S rRNA of the isolates suggests that they were identified as Micrococcus luteus 101 PB, Stenotrophomonas maltophilia 102 PB, Bacillus cereus 103 PB, Providencia vermicola 104 PB, Klebsiella pneumoniae 105 PB and Bacillus subtilis 106 PB. The use of mixed cultures in the present study showed more extensive removal of organic load (COD and BOD) than pure single cultures. Mixed cultures were found to reduce the pollutant dynamically. Thus, the mixed cultures C₁ (Bacillus cereus 103 PB and Bacillus subtilis 106 PB) were the most effective bacterial combination for use in biological treatment technology of POME having the highest COD and BOD reduction rate. C₁ produced the highest degradative activity in reducing COD (90.64 %) and BOD (93.11 %). The indigenous microbial isolates from POME were observed to possess potential to degrade organic components whereas the use of mixed cultures resulted in more extensive degradation of COD and BOD than pure single cultures. This suggests that mixed culture of bacteria in the present study can be used for bioremediation of environment contaminated with polluted wastewaters. This study, however, indicates the prospect of isolating indigenous microorganisms in the POME for effective biotreatment of POME.

This study was aimed at identifying indigenous microorganisms from palm oil mill effluent (POME) and to ascertain the microbial load. Isolation and identification of indigenous microorganisms was subjected to standard microbiological methods and sequencing of the 16S rRNA and 18S rRNA genes. Sequencing of the 16S rRNA and 18S rRNA genes for the microbial strains signifies that they were known as Micrococcus luteus 101PB, Stenotrophomonas maltophilia 102PB, Bacillus cereus 103PB, Providencia vermicola 104PB, Klebsiella pneumoniae 105PB, Bacillus subtilis 106PB, Aspergillus fumigatus 107PF, Aspergillus nomius 108PF, Aspergillus niger 109PF and Meyerozyma guilliermondii 110PF. Results revealed that the population of total heterotrophic bacteria (THB) ranged from 9.5 × 105 - 7.9 × 106 cfu/mL. The total heterotrophic fungi (THF) ranged from 2.1 × 104 - 6.4 × 104 cfu/mL. Total viable heterotrophic indigenous microbial population on CMC agar ranged from 8.2 × 105 - 9.1 × 106 cfu/mL and 1.4 × 103 - 3.4 × 103 cfu/mL for bacteria and fungi respectively. The microbial population of oil degrading bacteria (ODB) ranged from 6.4 × 105 - 4.8 × 106 cfu/mL and the oil degrading fungi (ODF) ranged from 2.8 × 103 - 4.7 × 104 cfu/mL. The findings revealed that microorganisms flourish well in POME. Therefore, this denotes that isolating native microorganisms from POME is imperative for effectual bioremediation, biotreatment and biodegradation of industrial wastewaters.