Toxicity of Diphenyltin Chloride on viable count of aerobic bacteria from River Benue.

Abstract

This research was carried out to determine the toxicity of diphenyltin chloride on viable count of freshwater aerobic bacteria. Water samples obtained from a depth of 15 cm at five sampling points along river Benue were spiked with 3 mM of DPTCl to have a duplicate setup of three (3) treatments. Organotin degradation was determined by measuring the decrease in the concentration of DPTCl using an X-ray fluorescence spectrophotometer on days 0, 14, 28, 42, and 56 and the viable count of bacteria was also determined using spread plate technique on MSA. DPTCl concentration was further varied (5 mM, 7 mM and 10 mM) to test levels of toxicity to viable count of bacteria as well as bacterial resistance. patio sequencing technique was used to determine the metagenomics of bacteria species capable of DPTCl degradation from the water samples. Percentage of chemically degraded (40.29%) during the initial two weeks of experiment when the bacterial population was high, was more than the percentage degraded (11.49%) during the last two weeks of the experiment when the biocidal effect of DPTCl had drastically reduced the bacterial population. Of the initial bacterial viable count of 47.2 x 102 that survived the 56 days degradation exercise, only 1.8x101 (0.38%) grew on 7 mM concentration of DPTCl, and none on 10 mM DPTCl. The impact of DPTCl on the viable count of bacteria was statistically significant. Stenotrophomonas spp (29.6%) was the dominant bacterium in DPT degradation, others include; Comamonas spp (9.31%), Microbacterium spp (8.41%) Pseudomonas viridiflava (4.18%), and Stenotrophomonas geniculata (3.46%). Organotins. Diphenyltin though a di-alkyl organotin, is equally a toxic and persistent pollutant that cannot be easily degraded without the use of nutrient amendment. The toxic effect of DPT as demonstrated in this study shows that TPT and other tri-alkyl organotin should not be considered detoxified especially against microorganisms simply because they have been de-alkylated.Sites contaminated by organotins should not be considered remediated until all di and mono alkyl derivatives are completely degraded. Since our natural environments usually have no sufficient nutrient amendments for elimination of pollutants, there is need to engage abiotic processes that can assist the activities of microorganisms in order to speed up remediation process.