In Vitro Assessment of the Inhibitory Effect of Sludge Against Fusarium oxyxporum f.sp cubense (Smith) Synder et Hansen (1940)

Date of Award


Document Type


Degree Name

Master of Science in Environmental Science


Environmental Science

First Advisor

Ma. Aileen Leah G. Guzman, PhD; Neil H. Tan Gana, PhD; Jewel Racquel S. Unson


One challenge resulting from wastewater treatment is the production of sludge as a by-product. Consequently, the global generation of sludge is increasing and is estimated to exceed 10,000 tons daily. Such amount produced can become a challenge in terms of its treatment and disposal. Recent literature has shown that sludge may elicit an inhibitory response against soil-borne pathogens, which may be valuable in managing soil infections. However, there is a need to conduct studies to understand the mechanisms of sludge’s inhibitory properties, primarily in the local setting. The study hypothesized that certain microorganisms with antagonistic activities against F. oxysporum can favorably grow in sludge environment using the different sludge extract treatments. Hence, the different physico-chemical characteristics of sludge were determined. Sludge extracts produced from different duration of drying time were tested for inhibitory response using in vitro setup. Identification of organisms with inhibitory properties was also done, and correlational analysis was also conducted. The highest percent Relative Inhibition Zone Diameter (%RIZD) (p < 0.05) is 78.30% in sludge extract from two months of drying, which also showed an increased amount of humic acid (10.29 C-mg/2mL), total nitrogen (2.83 ±0.09 %), and microbial respiration (8.51 C-mg/mL). The correlational analysis revealed that total bacterial count, total N, K, and microbial respiration contributed to the highest positive correlation among the parameters. Moreover, it was determined that the biotic component positively affects the inhibition of sludge against F. oxysporum. Despite showing high inhibitory potential, sludge must still undergo other treatment processes to produce mature sludge that passes regulatory standards set by the Philippines (PNS/BF 40:2016).

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