COMPARATIVE ANALYSIS OF RESIDENT CELLULOLYTIC POTENTIAL IN THE GUT WALL OF EPIGEIC VERSUS ENDOGEIC EARTHWORMS: OPTIMIZING LOW-COST SCREENING ASSAYS.

Abstract

This study investigated the cellulolytic potential of bacterial species isolated from 
the gut microbiota of epigeic and endogeic earthworms to comparatively evaluate 
their cellulose-degrading efficiency. Bacterial isolates were recovered using standard 
aseptic and microbiological techniques and identified through morphological and 
biochemical characterization. Cellulolytic activity was assessed by determining the 
cellulolytic index (CI), while enzymatic hydrolysis efficiency was quantified using the 
3,5-dinitrosalicylic acid (DNS) assay for reducing sugar estimation. Eight bacterial 
genera were identified, comprising Bacillus, Cellulomonas, Pseudomonas, 
Enterobacter, Klebsiella, Proteus, Acinetobacter, and Neisseria. Among the isolates, 
Cellulomonas spp. and Bacillus spp. exhibited the highest cellulolytic activities, with 
Cellulomonas spp. demonstrating superior performance (CI = 4.17 ± 0.15; DNS = 4.60 
± 0.17), indicating a strong capacity for cellulose hydrolysis. In contrast, Proteus 
vulgaris, Acinetobacter baumannii, and Neisseria sicca displayed comparatively low 
cellulolytic activities. Comparative evaluation of isolates from the two ecological 
groups revealed that bacterial communities associated with endogeic earthworms 
exhibited higher mean cellulolytic activity (CI = 2.93 ± 1.28; DNS = 2.89 ± 1.36) than 
those isolated from epigeic earthworms (CI = 1.79 ± 1.15; DNS = 1.56 ± 1.10). 
Nevertheless, independent-samples t-test analysis indicated that the observed 
difference was not statistically significant (p = 0.064). Despite the absence of 
statistical significance, the consistent pattern obtained from both CI and DNS 
assays suggests functional differences between the microbial communities and 
highlights the potential influence of earthworm ecological niches on cellulolytic 
capacity. Future studies incorporating molecular identification techniques and larger 
sample sizes are recommended to validate these findings and further explore the 
environmental and biotechnological applications of earthworm-associated cellulolytic 
microorganisms.