This study investigated the changes in the amino acid composition of mealworm substrates incubated separately with Bacillus subtilis EG1 and Leuconostoc mesenteroides BW2 cultures. The results revealed a reduction in the levels of 16 and 17 amino acids in the B. subtilis EG1 and L. mesenteroides BW2 treatments, respectively. The internal and external morphologies of mealworm chitin obtained after treatment with B. subtilis EG1 and L. mesenteroides BW2 cultures were investigated using light and polarized microscopy. Notably, protein removal from the exoskeleton was more effective with prolonged culture periods in the proteolytic bacterium B. subtilis EG1. Furthermore, Fourier-transform infrared (FT-IR) spectroscopy analysis indicated that the functional groups of chitin exhibited almost identical spectra across all treatments. The amino acid compositions of two mealworm types, Before Oil Extraction (BOE) and After Oil Extraction (AOE), cultured with B. subtilis EG1, were also investigated. Both BOE- and AOE-type mealworms exhibited the highest glutamic acid content and the lowest cystine content on day 0. Moreover, protein content in the exoskeleton of both BOE- and AOE-type mealworms decreased as the culture period with B. subtilis EG1 increased, as observed through light and pol...