Identification of Compatible Microbial Isolates with Hydrolytic Enzymes Producing Potential for Artificial Cross-kingdom Consortia Development

Abstract

In biotechnology, synthetic microbial consortia that combine bacterial and fungal species have great promise, especially for biomass degradation. This study aimed to identify compatible bacterial and fungal isolates with hydrolytic enzyme-producing potential for the development of artificial cross-kingdom microbial consortia. Environmental samples were taken from soil rich in decomposed matter, litter, agricultural soil, manure, and dumpsite soil. Standard microbiological methods were used to count, isolate, and characterize the microorganisms. Using media supplemented with starch, carboxymethyl cellulose, casein, tributyrin (with rhodamine B), and methylene blue, bacterial and fungal isolates were screened for the production of amylase, cellulase, protease, lipase, and ligninase, respectively. Cross-streaking method was used to assess the compatibility of the potent isolates in PDA supplemented with yeast extract. Fungal counts were highest in dumpsite soil (48.0 ± 11.3 CFU/g) and lowest in manure (3.0 ± 4.2 CFU/g), while bacterial counts were highest in manure/compost (31.0 ± 1.4 CFU/g) and lowest in litter-rich soil (9.0 ± 2.8 CFU/g). Bacterial isolates belong to the genera Bacillus, Pseudomonas, and Staphylococcus, while fungi were of Aspergillus, Penicillium, Mucor, Fusarium, and Rhizopus genera. Two (2) bacterial isolates produced both lipase and protease, while four (4) demonstrated lipase activity. Amylase activity was detected in five (5) fungal isolates, one (1) isolate produced both amylase and cellulase, while one (1) sole isolate tested positive for ligninase. Eight (8) cross-kingdom consortia were developed, though incompatibility was observed in the 7th and 8th consortia. These findings support the rational design of compatible microbial consortia for application in composting, and industrial bioprocesses.

Keywords: hydrolytic enzymes, microbes, compatibility, composting