Abstract
Background
Salinity negatively affects seed germination and crop yields. This study explored chitinolytic bacteria from the Lipar Pink Wetland as potential wheat seed-priming agents under salt stress. Using shrimp shell waste, chitinase-producing bacteria were isolated, and their live cells and chitinase-active supernatants produced on colloidal chitin were tested as wheat seed-priming treatments in normal and saline conditions.Results
Chitin extraction from shrimp shells using a conventional acid-alkali process yielded 53.3-56.7% chitin on a dry-weight basis. FTIR analysis confirmed characteristic functional groups, and FESEM revealed a compact, flake-like morphology. Among 45 bacterial isolates screened on chitin-containing media, three strains (S1, S49, and S80) formed clear hydrolysis halos and were selected for further analysis. Their chitinase-active extracellular fractions showed broad activity across 35-50 °C, with optimum temperatures of 40 °C for Sup49 and 45 °C for Sup1 and Sup80. Sup1 exhibited the highest activity under acidic conditions, whereas Sup49 and Sup80 performed best at near-neutral to slightly alkaline pH. Sup80 also showed superior thermostability at 60 °C and greater tolerance to salinity and EDTA than the other fractions. Partial 16 S rRNA phylogeny placed S49 and S80 within Bacillus cereus sensu lato-related lineages. Seed priming showed that 150 mM sodium chloride reduced wheat performance, decreasing germination in the untreated control from 73.74 ± 7.82% under normal conditions to 34.44 ± 1.92% under salinity. Under normal conditions, shorter priming durations were generally more effective. Hydropriming for 3 and 7 h produced high germination rates, while N-S80.3 h produced the numerically greatest total seedling length. Under salinity, S-Sup1.3 h showed the strongest numerical overall response, increasing germination to 74.67 ± 4.62% and producing the highest shoot length, root length, total seedling length, and seedling vigor index among saline treatments with available growth data. However, its GP was statistically grouped with S-Hydropriming.24 h and S-Sup49.7 h.Conclusions
Chitinolytic Bacillus-related isolates and their chitinase-active extracellular supernatants showed preliminary potential for wheat seed priming under salinity. Because the supernatants were not purified chitinase preparations, their effects may reflect combined extracellular metabolites and chitin-derived products. Future research should focus on microbial traits, plant stress physiology, pathogen challenges, biosafety, and field performance.