B. methylotrophicus strain 39b exhibited antibacterial activity against phytopathogenic A. tumefaciens C58 and B6 both in vitro and in vivo. Lipopeptides are the main compounds that confer the biocontrol ability. This strain has the potential to be developed as a biological control agent for crown gall disease. © 2016 Society of Chemical Industry.

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The findings could be useful for growers and nursery men who are particularly interested in the biocontrol of the crown gall disease.

In this study, a high rate of C trachomatis infection was observed. The detection of this microorganism should be introduced in systematic surveillance of Tunisian FSW.

Background: The OmcB protein is one of the most immunogenic proteins in C. trachomatis and C. pneumoniae infections. This protein is highly conserved leading to serum cross reactivity between the various chlamydial species. Since previous studies based on recombinant proteins failed to identify a species specific immune response against the OmcB protein, this study evaluated an in silico predicted specific and immunogenic antigen from the OmcB protein for the serodiagnosis of C. trachomatis infections.

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BackgroundThis epidemiological study was carried out in Sfax (south of Tunisia) and focused on genital Chlamydia trachomatis (C. trachomatis) genovar distribution.MethodsOne hundred and thirty seven genital samples from 4067 patients (4.2%) attending the Habib Bourguiba University hospital of Sfax over 12 years (from 2000 to 2011) were found to be C. trachomatis PCR positive by the Cobas Amplicor system. These samples were genotyped by an in house reverse hybridization method.ResultsOne hundred and eight (78.8%) samples contained only one genovar and 29 (21.2%) samples contained two or three genovars. Genovar E was the most prevalent (70.8%) single genovar and it was detected in 90.6% of all the cases. Genovars J, C and L1-L3 were not detected in our samples whereas ocular genovars A and B were in 5 cases. All the five cases were mixed infections. Men had more mixed infections than women (p=0.02) and were more frequently infected by genovars F and K (p<0.05). No associations between current infection, infertility and the genovar distribution were observed. Patients coinfected with Neisseria gonorrhoeae were also significantly more frequently infected with mixed genovars (p=0.04).ConclusionsIn conclusion, we have reported a high prevalence of genovar E and of mixed infections in our study population. Such data could have implications for the control and vaccine development of C. trachomatis in Tunisia.

This study aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall disease. The relationship between the strain biocontrol ability and their in vitro studied traits was investigated to identify the most important factors to be considered for the selection of effective biocontrol agents. In fact, previous selection procedure relying only on in vitro antibacterial activity was shown to be not suitable in some cases. A direct plant-protection strategy was performed to screen the 32 Bacillus biocontrol agent candidates. Moreover, potential in vitro biocontrol traits were investigated including biofilm formation, motility, hemolytic activity, detection of lipopeptide biosynthetic genes (sfp, ituC and bmyB) and production of antibacterial compounds. The obtained results indicated high correlations of the efficiency of the biocontrol with the reduction of gall weight (p = 0.000) and the antibacterial activity in vitro (p = 0.000). Moreover, there was strong correlations of the efficiency of the biocontrol (p = 0.004) and the reduction in gall weight (p = 0.000) with the presence of the bmyB gene. This gene directs the synthesis of the lipopeptide bacillomycin belonging to the iturinic family of lipopeptides. These results were also confirmed by the two-way hierarchical cluster analysis and the correspondence analysis showing the relatedness of these four variables. According to the obtained results a new screening procedure of Bacillus biocontrol agents against crown gall disease could be advanced consisting on two step selection procedure. The first consists on selecting strains with high antibacterial activity in vitro or those harbouring the bmyB gene. Further selection has to be performed on tomato plants in vivo. Moreover, based on the results of the biocontrol assay, five potent strains exhibiting high biocontrol abilities were selected. They were identified as Bacillus subtilis or Bacillus amyloliquefaciens. These strains were found to produce either surfactin or surfactin and iturin lipopeptides. In conclusion, our study presented a new and effective method to evaluate the biocontrol ability of antagonistic Bacillus strains against crown gall disease that could increase the efficiency of screening method of biocontrol agents. Besides, the selected strains could be used as novel biocontrol agents against pathogenic Agrobacterium tumefaciens strains.