Paenibacillus polymyxa strains produce fusaricidin type compounds that are active against a wide variety of Gram-positive bacteria and fungi. Growth and production of fusaricidin type antifungal compounds by P. polymyxa SQR-21 were compared in tryptone broth supplemented with three concentrations (200, 400 and 600 µM) of lead. The data revealed that the growth of P. polymyxa increased by 7-34 % and fusaricidin type compounds production increased by 15-70 % with the increase in concentration of lead ion (Pb2+). The increase in Pb2+ concentration, decreased the intracellular carbohydrate contents but increased the intracellular protein and lipid contents, however, higher levels of Pb2+ inhibited the intracellular protein and lipid contents. On the other hand, extracellular protein contents were decreased and extracellular polysaccharide contents were increased with the increase in Pb2+ contents in liquid culture. In addition, the regulatory effects of lead were also reflected by decrease of total RNA and increase of relative expression of the six module-containing nonribosomal peptide synthetase (FusA) when the lead treated experimental samples were compared with the untreated controls. The Pb2+ seems to be directly or indirectly correlated with the production of fusaricidin type antifungal compounds. This information will aid in developing fermentation technology for maximum antibiotic production.
HONGSHENG WU ,SHEN QIRONG ,YANGCHUN XU ,WASEEM RAZA ,
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