Immunization with a nontoxic naturally occurring Clostridium perfringens alpha toxin induces neutralizing antibodies in rabbits.

Clostridium perfringens alpha toxin, encoded by plc gene, has been implicated in gas gangrene, a life threatening infection. Vaccination is considered one of the best solutions against Clostridium infections. Although studies have identified many low quality clostridial vaccines, the use of recombinant proteins has been considered a promising alternative. Previously, a naturally occurring alpha toxin isoform (αAV1b) was identified with a mutation at residue 11 (His/Tyr), which can affect its enzymatic activity. The aim of the present study was to evaluate whether the mutation in the αAV1b isoform could result in an inactive toxin and was able to induce protection against the native alpha toxin. We used recombinant protein techniques to determine whether this mutation in αAV1b could result in an inactive toxin compared to the active isoform, αZ23. Rabbits were immunized with the recombinant toxins (αAV1b and αZ23) and with native alpha toxin. αAV1b showed no enzymatic and hemolytic activities. ELISA titration assays showed a high titer of both anti-recombinant toxin (anti-rec-αAV1b and anti-rec-αZ23) antibodies against the native alpha toxin. The alpha antitoxin titer detected in the rabbits' serum pool was 24.0 IU/mL for both recombinant toxins. These results demonstrate that the inactive naturally mutated αAV1b is able to induce an immune response, and suggest it can be considered as a target for the development of a commercial vaccine against C. perfringens alpha toxin.

Complete mitochondrial genome sequence of Piaractus mesopotamicus (Holmberg, 1887).

The migratory species Piaractus Mesopotamicus, popularly known as the pacu, was determined to have a complete mitochondrial genome of 16,722 bp with 45% GC content. The genome contained 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and a 1048 bp Control Region (D-loop). Almost all the PCGs used the standard ATG start codon, except for Cox1 that used a GTG start codon. Five of the 13 PCGs had a TAA stop codon, two had the incomplete stop codon TA- (Atp6 and Cox3), and five had the incomplete stop codon T-- (Nd2, Cox2, Nd3, Nd4, and Cytb). AGG was the stop codon of Cox1.

Complete mitochondrial genome sequence of Brycon orbignyanus (Characiformes, Bryconidae).

We report the whole mitochondrial genome of the Brycon orbignyanus, commonly known as the piracanjuba. The mitogenome was determined to be a circular, 16,800 bp DNA molecule, containing 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes and one 1160 bp noncoding control region. Twelve of the PCGs were located on the heavy strand, and one PCG (Nd6) was located on the light strand. The most common start codon was ATG; however, the Cox1 gene displayed the GTG start codon. Seven PCGs had incomplete stop codons: specifically, Cox2, Cox3, Nd3, Nd4, and Cytb contained the T- - codon, and Nd2 and Atp6 contained the TA- codon. The Cox1 gene contained the AGG stop codon.

Survey of microbial enzymes in soil, water, and plant microenvironments.

Detection of microbial enzymes in natural environments is important to understand biochemical activities and to verify the biotechnological potential of the microorganisms. In the present report, 346 isolates from soil, water, and plants were screened for enzyme production (caseinase, gelatinase, amylase, carboxymethyl cellulase, and esterase). Our results showed that 89.6% of isolates produced at least one tested enzyme. A predominance of amylase in soil samples, carboxymethyl cellulase in plants, as well as esterase and gelatinase in water was observed. Interesting enzymatic profiles were found in some microenvironments, suggesting specificity of available nutrients and/or natural selection. This study revealed the potential of microorganisms present in water, soil, and plant to produce important enzymes for biotechnological exploration. A predominance of certain enzymes was found, depending on the type of environmental sample. The distribution of microbial enzymes in soil, water and plants has been little exploited in previous reports.