Antibacterial substance produced by Streptomyces sp. No. 87

An antimicrobial substance produced by Streptomyces sp. No. 87 was partially purified and studied for its antibacterial characteristics using the swab paper disc technique. The cell-free culture filtrateshowed antibacterial activity against several species of pathogens including Gram-positive bacteria, i.e. Bacillus cereus ATCC 11778, B. subtilis TISTR 008, B. megaterium, Staphylococcus aureus, S. aureusATCC 25923, and S. epidermidis and Gram-negative bacteria, i.e Klebsiella pneumoniae ATCC 27736, K. pneumoniae, Salmonella typhi ATCC 5784, Vibrio cholerae and Xanthomonas sp. 60% ammoniumsulfate precipitation of the culture supernatant shows markedly antibacterial activity against B. cereus ATCC 11778. Then supernatant was purified by gel filtration chromatography with sephadex G-25 resin.Five peaks namely P1, P2, P3, P4 and P5 were obtained. Results indicate that P3 is the only peak possessing the antibacterial activity, therefore, the final purification of P3 was conducted using FPLCwith a superdex 30 column. Only one peak, namely P3-1 retained the antibacterial activity. P3-1 showed that its activity was insensitive to proteolytic enzymes such as trypsin, pepsin and proteinase K. Inaddition, the activity of P3-1 could be observed temperatures of 50 -121oC and no protein or polypeptide band was seen when P3-1 was analyzed by SDS-PAGE. These results suggest that P3-1 might not beproteinacious in nature

Antibacterial activity from Siamese crocodile (Crocodylus siamensis) serum

Antibacterial agents were purified from Siamese crocodile serum by anion exchange, gel filtration and reversed phase HPLC. Six antibacterial agents designed as Hp14, Hp15, Hp17, Hp31, Hp36 and Hp51 were purified and proved to carry activity against Salmonella typhi, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, Pseudomonas aeruginosa and Vibrio chorelae. The mass analysis of MALDI-TOF for antibacterial agent of Hp14, Hp15 and Hp51 revealed that they are small molecule with a molecular mass less than 1 kDa. The scanning electron microscopy demonstrated that these agents targeted the bacterial membrane and they act like as antimicrobialpeptides. The antibacterial agent in the serum may represent the first line of an immune system in a freshwater crocodile

Characterization of the allergen Sol gem 2 from the fire ant venom, Solenopsis geminata

Sol i 2 is a potent allergen in Solenopsis invicta venom, and most humans exhibit reactivity to it. The Sol gem 2 allergen found in the venom of the Thai tropical fire ant Solenopsis geminata was analysed in the present study. The protein was present in higher amounts than other proteins, as determined by SDS-PAGE, and presumably has allergenic properties similar to those of Sol i 2. Sol gem 2 molecular weight is 28 and 15 kDa, respectively, under non-reducing and reducing conditions, indicating that its native form is a dimer. LC-MS/MS analysis confirmed its similarity to Sol i 2. The mono/dimeric form of Sol gem 2 was determined to be relevant by proteomic approach and immunoblotting. An anti-Sol gem 2 antibody was produced in mice, with a titer greater than 1:800 according to the Western blotting analysis. The Sol gem 2-neutralising activity of this antibody was determined in crickets. The paralytic dose 50 (PD50) of crude S. geminata venom was elevated from 0.18 mg/g of body weight to more than 0.90 mg/g of body weight after preincubation with antibody at a ratio of 1:1. These results suggest that Sol gem 2 plays an important role in mediating the effects of the piperidine derivatives in the venom