Chlamydomonas reinhardtii-derived mytichitin-CB/hispidalin chimera efficiently inhibits the growth of bacteria by disrupting their membrane integrity

The antimicrobial peptides Mytichitin-CB and Hispidalin were isolated from Mytilus coruscus and Benincasa hispida, respectively. Our previous studies showed that Mytichitin-CB, when expressed in Chlamydomonas reinhardtii, inhibits the bacterial growth with moderate efficiency. Naturally isolated or Pichia pastoris-expressed Hispidalin also exerts moderate efficiency for inhibiting the growth of bacteria. Here, we expressed a chimeric peptide composed of Mytichitin-CB and Hispidalin that we named as MCH in C. reinhardtii. MCH was stably expressed and its yield accounted for 0.18% of total soluble proteins of the host cells. C. reinhardtii-derived MCH inhibited the growth of both Gram-positive and Gram-negative bacteria by disrupting their cell membrane integrity. Its minimal inhibitory concentration (MIC) were ranged between 20 and 40 mu g/mL, demonstrating that MCH is more potent for inhibiting the bacterial growth than individual microalgae-expressed Mytichitin-CB and yeast-expressed Hispidalin. Of more importance, MCH was temperature- and pH-tolerant, protease-resistant and exhibited low hemolytic activity against rat erythrocytes and low cytotoxicity to human embryonic kidney 293 (HEK 293) and Madin-Darby bovine kidney (MDBK) cells. Therefore, we conclude that C. reinhardtii-derived chimeric peptide MCH has a great potential for being developed to replace traditional antibiotics in the future.

Automated summary

Researchers expressed antimicrobial peptides Mytichitin-CB and Hispidalin in Chlamydomonas reinhardtii and created a chimeric peptide called MCH. MCH demonstrated high efficiency in inhibiting bacterial growth and displayed strong resistance to temperature, pH, and proteases, while showing low toxicity towards erythrocytes and human kidney cells.