Lactobacillus plantarum is an important lactic acid bacterium, usually found as natural inhabitant of food, such as fermented vegetables and meat products. However, little information about lactic acid bacteria, especially concerning L. plantarum, as a source of useful enzymes has been reported. The aim of this study was to clone, express in Escherichia coli, purify, and characterize an esterase from L. plantarum ATCC 8014. The esterase gene (1014 bp) was amplified and cloned in pET14b expression vector to express a His(6)-tagged protein in E. coli. Recombinant L. plantarum esterase was purified by Ni-NTA resin, presenting an apparent molecular mass of about 38 kDa. It presented highest activity at pH 6.0 and 40 degrees C. Also, it presented preference for p-nitrophenyl butyrate, but hydrolyzed more efficiently p-nitrophenyl acetate. Besides, this study shows, for the first time, CD data about secondary structure of an esterase from L. plantarum.

The plant growth promoting bacteria Herbaspirillum seropedicae SmR1 is an endophytic diazotroph found in several economically important crops. Considering that methods to monitor the plant-bacteria interaction are required, our objective was to develop a real-time PCR method for quantification of PGPB H. seropedicae in the rhizosphere of maize seedlings. Primer pairs were designed, and their specificity was verified using DNA from 12 different bacterial species. Ten standard curves of qPCR assay using HERBAS1 primers and tenfold serial dilutions of H. seropedicae SmR1 DNA were performed, and PCR efficiency of 91 % and correlation coefficient of 0.99 were obtained. H. seropedicae SmR1 limit of detection was 10(1) copies (corresponding to 60.3 fg of bacterial DNA). qPCR assay using HERBAS1 was used to detect and quantify H. seropedicae strain SmR1 in inoculated maize roots, cultivated in vitro and in pots, harvested 1, 4, 7, and 10 days after inoculation. The estimated bacterial DNA copy number per gram of root was in the range 10(7)-10(9) for plants grown in vitro and it was around 10(6) for plants grown in pots. Primer pair HERBAS1 was able to quantify H. seropedicae SmR1, and this assay can be useful for monitoring plant-bacteria interaction.

Lipases are well-known enzymes extensively used in industrial biotransformation processes. Besides, their structural and catalytic characteristics have attracted increasing attention of several industries in the last years. In this work, we used biophysical and molecular modeling tools to assess structural properties of Staphylococcus xylosus lipase (SXL). We studied the thermal unfolding of this protein and its zinc-dependent thermotolerance. We demonstrated that SXL is able to be active and stable at moderate temperatures, but this feature is only acquired in the presence of Zn(2+). Such characteristic indicates SXL as a zinc-dependent metallolipase.

The genetically modified common bean Embrapa 5.1, developed by Brazilian Agricultural Research Corporation (Embrapa), is the first commercial GM plant produced in Latin America. It presents high resistance to the Bean golden mosaic virus. In this work, primers and probes targeting a taxon-specific reference DNA sequence for the common bean (Phaseolus vulgaris L.) and a construct-specific DNA sequence of Embrapa 5.1 GM common bean were successfully developed. The primers and probes showed high specificity for the target detection. Both methods showed suitable efficiency and performance to be used as an endogenous target for detection of common bean DNA and for construct-specific detection of GM common bean Embrapa 5.1, respectively. Both real-time PCR assays proved to be valuable for future assessment of interlaboratory studies.