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Background <p>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.</p> Results <p>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&#xa0;°C, with optimum temperatures of 40&#xa0;°C for Sup49 and 45&#xa0;°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&#xa0;°C and greater tolerance to salinity and EDTA than the other fractions. Partial 16&#xa0;S rRNA phylogeny placed S49 and S80 within <i>Bacillus cereus sensu lato</i>-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&#xa0;h produced high germination rates, while N-S80.3&#xa0;h produced the numerically greatest total seedling length. Under salinity, S-Sup1.3&#xa0;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&#xa0;h and S-Sup49.7&#xa0;h.</p> Conclusions <p>Chitinolytic <i>Bacillus</i>-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.</p>

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Biochemical characterization of chitinolytic Bacillus isolates from a hypersaline wetland and their biopriming potential for improving wheat germination under salinity stress

  • 期刊论文

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  • 发表日期：

    2026年6月23日

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  • Sara Abedini,
  • Shohreh Ariaeenejad,
  • Azadeh Lohrasbi-Nejad

摘要

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.