A NEW BACTERIAL ISOLATE PAENIBACILLUS ALVEI NP75 THAT PRODUCES TWO NEW PEPTIDE ANTIBIOTICS

摘要

Two new peptide antibiotics were secreted by a gram positive bacterial strain isolated from fermented tomato fruit. Based on its 99% 16S rDNA sequence similarity with Paenibacillus alvei, the isolate was designated as Paenibacillus alvei NP75. Among these two peptides, one is active against Gram positive pathogens while the other against Gram negative pathogens; thus these peptides were named as paenibacillin P and paenibacillin N, respectively. After the purification of those peptide antibiotics from the cell free culture supernatant by RP-HPLC, they were analyzed for their temperature sensitivity and susceptibility to proteases. Higher-temperature tolerant paenibacillin N was easily degraded by proteinase K, while the temperature sensitive paenibacillin P was not affected by any of the proteases used in this study other than a specific protease that was secreted by the same NP75 strain. The molecular mass of the paenibacillin N (1.157 kDa) and paenibacillin P (1.910 kDa) were identified in mass spectrometry analysis. MALDI-TOF Mass spectrometry analysis of the above peptide antibiotics further showed that they are different from one another as well as from other functionally related known peptide antibiotics. The plasmid curing studies in NP75 strains with SDS treatment reveals that the secretion of paenibacillin P encoded in the plasmid but paenibacillin N was not defined in the plasmid. We are reporting first of its kind the co-production of two different new peptide antibiotics from a single bacterial isolate of P. alvei strain.