Cellulolytic potential of a novel strain of Paenibacillus sp. isolated from the armored catfish Parotocinclus maculicauda gut

A cellulolytic bacterial strain, designated P118, isolated from the gut of the tropical fish Parotocinclus maculicauda was identified as belonging to the genus Paenibacillus based on phenotypic and chemotaxonomic characteristics and the 16S rRNA gene sequence. The novel strain was Gram-positive, spore-forming and rod-shaped. Catalase but not oxidase was produced. Carboxymethylcellulose was hydrolyzed but starch or gelatin was not. Acetoin production was negative whereas nitrate reduction and urease production were positive. Many carbohydrates served as carbon sources for growth. MK-7 was the predominant isoprenoid quinone. Anteiso-C15:0 (38.73 percent) and C16:0 (20.85 percent) were the dominant cellular fatty acids. Strain P118 was closely related to Paenibacillus amylolyticus NRRL NRS-290, P. pabuli HSCC 492, P. tundrae Ab10b, P. xylanexedens B22a, and P. tylopili MK2 with 98.3-98.8 percent 16S rRNA gene sequence similarity. The results presented here suggest that strain P118 represents a novel species of the genus Paenibacillus and it is a potential strain for further studies concerning its role in the production of industrially important products from cellulosic biomass.

Extracellular serine-proteinases isolated from Streptomyces alboniger: Partial characterization and effect of aprotinin on cellular structure

Streptomyces alboniger ATCC 12461 grown in brain heart infusion (BHI) medium produced two extracellular serine-proteinases, denoted SP I and SP II, which were purified by ammonium sulfate precipitation and aprotinin-agarose affinity chromatography. SP I was purified 88,9-fold and SP II 66,7- fold, with 33.4 percent and 10.4 percent yield, respectively. The optimum pH for the proteinases activity, using a-N-p-tosyl-L-arginine-methyl ester (TAME) as substrate, was 9-10 and the optimum temperature was 37ºC. The proteolytic activity of SP I and SP II was inhibited by aprotinin and SP I was partially inhibited by leupeptin, both serine-proteinase inhibitors. S. alboniger growth in BHI-liquid medium decreased when 5 mg/ml, 10 mg/ml of aprotinin was used, being completely inhibited with 20 mg/ml and 40 mg/ml. At the ultrastructural level, aprotinin-treated S. alboniger cells showed swelling of the bacterial body and condensation of the genetic material, probably related to the inhibition of its growth

Culture filtrates of actinomycetes isolated from tropical soils inhibit trypanosoma cruzi replication in vitro

Oitenta e quatro amostras de actinomycetos isolados de solos brasileiros, mais 4 obtidas da ATCC, foram testadas quanto à capacidade de inibir T. cruzi. Nove delas (ca. 10 por cento), quando cultivadas em meio mineral líquido contendo glicerol e peptona ou nitrato, com eventual adiçäo de extrato de levedura e/ou tirosina, excretaram compostos capazes de inibir completamente os parasitos. Outras 22 (ca. 25 por cento) produziram compostos que mostraram um efeito parcial. Para algumas amostras, a composiçäo do meio e o período de incubaçäo foram parâmetros importantes na capacidade inibitória dos filtrados das culturas. Em meios contendo ingredientes de baixo custo (amido solúvel, farinha de arroz, farinha de milho), a maioria das amostras testadas, que no estudo prévio havia determinado em efeito inibitório parcial, näo confirmou este efeito neste segundo experimento. Apenas 4 dentre as 16 amostras testadas foram parcialmente ativas. Três dentre as 4 amostras da ATCC foram ativas contra T. Cruzi, duas das quais já conhecidas como produtoras de antibióticos ativos contra bactérias, mas näo contra protozoários. O efeito de alguns sobrenadantes de cultura sobre T. cruzi foi acompanhado por microscopia de contraste de fase, para a detecçäo de células alteradas e imobilizadas