In this study, we explored the possibility of utilizing the succulent pulp of Spondias mombin (SM) as feedstock for the synthesis of biosurfactants by Pseudomonas spp. The cultures were composed of basic mineral medium amended with SM, SM + glucose, glucose (GLC), and nutrient broth (NB) as carbon sources. Biosurfactant production was determined by surface-active properties such as hemolysis, emulsification index (E 24 ), drop collapse, oil-spreading assays, and reduction of surface tension. The stability of the biosurfactants was monitored across different temperature and pH regimes while chemical components of the extracted biosurfactants were determined by thin-layer chromatography. Biosurfactants synthesized from SM as sole substrate showed the highest emulsification index (56.35%), oil-spreading capacity (4.4 ± 1.31 cm), hemolysis (3.10 ± 0.02 cm), the shortest time for drop collapse (30 s), and surface tension reduction (24 mN/m). Biosurfactant concentrations ranged from 0.07 ± 0.01 in the NB to 2.08 ± 0.01 g/L in the media amended with SM. Chemical characterization revealed significant concentrations of carbohydrates and lipids in the biosurfactant produced from SM (1.2 ± 0.17 and 0.88 ± 0.04 g/L, respectively) when compared to SM + glucose (0.92 ± 0.05, and 0.62 ± 0.02 g/L, respectively), glucose (0.35 ± 0.04 and 0.13 ± 0.02 g/L, respectively), and nutrient broth (0.06 ± 0.03 and 0.01 ± 0.01 g/L, respectively). The biosurfactants were stable over a wide range of temperature while E 24 increased with pH. Our results show the viability of SM fruit pulp as low-cost feedstock for industrialscale production of biosurfactants using Pseudomonas spp.

Bioremediation employing the action of microbes alone has been shown to be inadequate. The aim of this study was to evaluate the efficacy of sewage sludge (SS) in enhancing bioremediation of diesel oil-polluted soil. Diesel oil was introduced into the soil at the concentration of 10 % (v/w) and mixed with 5%, 10% and 15% (w/w) of sewage sludge. The remediation of the oil was determined gravimetrically using n-hexane as extractant. Effectiveness of the remediation strategy was assessed by the seed germination toxicity test. At the end of forty-two days, 32.22 % oil loss was recorded in the unamended polluted soil while 58.33% oil loss was recorded in the soil amended with sewage sludge. Hydrocarbon-utilizing bacteria (HUB) counts were significantly higher (P≤0.05) in the sewage sludgeamended options, ranging from 5.3 ±0.9 x 10 6 to 12.3±0.75 × 10 6 CFU/g soil, as compared to the unamended control soil which gave 1.0 × 10 6 -3.8 × 10 6 CFU/g of soil. The hydrocarbon-utilizing bacteria isolated from both the control and amended soils were identified tentatively as Bacillus cereus, Pseudomonas putida, Micrococcus varians, Corynebacterium sp, Acinetobacter sp and Bacillus licheniformis based on their cultural, morphological and biochemical characteristics. The fungal counts in the SS-amendment options were also higher than was recorded in the control option ranging from 3.8x 10 5 ± 0.2 to 11.6x 10 5 ±0.25.Aerobic fungi isolated were Aspergillus niger, Aspergillus flavus, Fusarium sp, Cladosporium sp and Penicillium sp. The highest oil loss and germination indices were recorded in SS-amended options. There was a significant difference (P≤0.05) in oil loss and germination index between the unamended control soil and amended soil.

The effectiveness of pig droppings (PD) in enhancing bioremediation of diesel oil-polluted soil was investigated gravimetrically for a period of 42 days. Polluted soil was amended with 5%, 10% and 15% (w/w) of PD. Loss of total petroleum hydrocarbon (TPH), microbial growth and germination indices were all monitored throughout the study period. At the end of 42 days, there was significant oil loss of 48.54% in the amended soil. Hydrocarbonutilising bacterial (HUB) counts were higher in the amended option ranging from 4.2 x 10 6 ±0.69 to 10.9 x 10 6 ± 0.41 CFU/g. The HUB isolated from the oil-contaminated soil were identified tentatively as Bacillus cereus, Pseudomonas putida, Micrococcus varians, Corynebacterium sp and Staphylococcus sp. Similarly, fungal counts ranged from 3.0 x 10 5 ±0.21 to 10.9 x 10 5 ±0.33 CFU/g. Aerobic fungi isolated were identified tentatively as Aspergillus niger, Aspergillus flavus, Fusarium sp, Cladosporium sp and Penicillium sp. Germination index of 53.4% was recorded in the amended option. Oil loss and microbial growth were significantly higher ((P≤ 0.05) in the amended option than the control option. Pig droppings, therefore can offer a good alternative in bioremediation of diesel oil-polluted soil.

The potential of potato skin (PS) to enhance bioremediation of soil polluted with used motor oil was investigated gravimetrically for a period of 42 days. Polluted soil was amended with 5%, 10% and 15% (w/w) of PS. Loss of total petroleum hydrocarbon (TPH), microbial growth and germination indices were all investigated throughout the study period. At the end of 42 days, there was significant oil loss of 73.85% in the amended soil. Hydrocarbon-utilizing bacterial (HUB) counts were significantly higher(P≤0.05) in the amended option ranging from 6.7 x 10 6 to 22.3 x 10 6 CFU/g. The HUB isolated from the oil-contaminated soil were identified tentatively as belonging to the genera: Bacillus, Arthrobacter, Rhodococcus, Corynebacterium, Pseudomonas, Staphylococcus and Acinetobacter. Similarly, fungal counts ranged from 4.8 x 10 5 to 59.0 x 10 5 CFU/g. Aerobic fungi isolated were identified tentatively as Aspergillus niger, Aspergillus sp., Pennicillum sp., Phialophora sp., Cladosporium sp. and Verticillum sp. Germination index of 69.46% was recorded in the amended option. Oil loss and microbial growth were significantly higher (P≤ 0.05) in the amended option than the control option. Potato skin, therefore can offer a good alternative in bioremediation of soil polluted with used motor oil.