Isolation, Characterisation and Cellulolytic Screening of Cultivable Bacteria Associated with Allonothrus russeolus russeolus Wallwork, 1960 (Acari: Oribatida) from Kerala, India
Soumya Chandran
PG & Research Department of Zoology, Govt. College Madappally, University of Calicut, Kerala, India.
E. Julie
*
Providence Women’s College, University of Calicut, Kerala, India.
I. V. Ashigha
PG & Research Department of Zoology, Govt. College Madappally, University of Calicut, Kerala, India.
P. Thejass
PG & Research Department of Zoology, Govt. College Madappally, University of Calicut, Kerala, India.
*Author to whom correspondence should be addressed.
Abstract
Background: Oribatid mites contribute substantially to litter decomposition and nutrient cycling, but their digestive functions may partly depend on associated microorganisms. However, information on the cultivable cellulolytic bacteria associated with Allonothrus russeolus russeolus remains limited, particularly in Kerala, India.
Aims: This study aimed to isolate and characterise culturable bacteria associated with Allonothrus russeolus russeolus Wallwork, 1960, using standard biochemical tests, qualitatively evaluate their cellulolytic potential, and identify representative isolates by 16S rRNA sequencing.
Study Design: Experimental, laboratory-based study.
Place and Duration of Study: Oribatid mites were collected and identified at Government College Madappally, Vadakara, Calicut, Kerala, India, in July 2025. Bacterial isolation, cellulolytic screening, and 16S rRNA sequencing were performed at Biomes-care Laboratory, Malappuram, Kerala, India, from July to September 2025.
Methodology: Adult A. russeolus russeolus mites were surface-sterilised, homogenised, and plated on nutrient agar. Distinct colonies were purified and subjected to standard biochemical assays and Gram staining. Cellulolytic activity was evaluated on carboxymethyl cellulose agar plates. Isolates yielding successful DNA extraction and PCR amplification were identified by 16S rRNA sequencing.
Results: Purification and biochemical testing revealed six distinct bacterial isolates. Gram staining characterised four isolates as Gram-positive rods and two as Gram-negative rods. Five of the six isolates showed cellulolytic activity on CMC agar. Successful 16S rRNA sequencing identified three isolates as Priestia megaterium, a member of the Bacillus cereus group, and Pantoea dispersa.
Conclusion: This study provides preliminary baseline information on the cultivable cellulolytic bacterial community associated with A. russeolus russeolus. The occurrence of cellulolytic bacteria suggests a possible role for mite-associated microorganisms in cellulose degradation and highlights the need for further studies on the functional significance of microbial associations in oribatid mites.
Keywords: Allonothrus russeolus russeolus, oribatid mites, cultivable bacteria, mite-associated microbiota, cellulolytic activity, carboxymethyl cellulose, Congo red assay, 16S rRNA sequencing, Priestia megaterium, Pantoea dispersa