Transcriptional analysis of bacteriocin production by malt isolate Lactobacillus sakei 5.

Malt isolate Lactobacillus sakei 5 produces three bacteriocins, sakacin P, sakacin T and sakacin X. The structural and regulatory genes for sakacin T and sakacin X are part of the sakacin TX locus, which consists of two adjacent, but divergently oriented gene clusters. Primer extension transcriptional analysis pointed to the existence of three distinct promoters within the sakacin TX locus, indicating that the three-component regulatory system in this locus is atypical in the sense that it is divided into a pheromone-specifying operon and an operon containing the genes for the histidine protein kinase and response regulator. Quantitative real-time PCR analyses showed that a transient increase in the expression of these two regulatory operons precedes transcription of the bacteriocin genes and appearance of bacteriocins in the culture medium. The identified promoters of the sakacin TX locus contain putative regulatory sequences (direct repeats) at corresponding positions in front of their -10 regions, which are likely to play a role in gene regulation.

Paediatric tuberculosis in a Pacific Islands community in New Zealand.

OBJECTIVES: To describe the demographic, clinical and management aspects of an outbreak of tuberculosis (TB) within a paediatric Pacific Island community in Auckland, New Zealand, in 2002-2003. METHODS: The index and source case are described along with details of the extensive contact tracing that was undertaken in this community. RESULTS: A total of 24 children were diagnosed with TB over an 11-month period. All cases were found to be epidemiologically linked to the one source case, mother of the index case. This total included 22 children with pulmonary disease, 1 case of miliary disease (index case) and 1 of cervical adenitis. Only 58% had symptoms at diagnosis and only 5 presented to medical attention with symptoms, the remainder had symptoms disclosed after contact tracing occurred. The Mycobacterium tuberculosis isolate was fully sensitive and all children (excluding the child with miliary disease) received short course directly observed therapy. One child developed hepatotoxicity requiring modification of his drug regimen. CONCLUSIONS: Children are at high risk of developing active disease after exposure to TB. The study describes the minimal symptoms manifested in many of the children with significant radiological changes consistent with pulmonary TB. This highlights the need to consider Mantoux testing and chest X-rays for children presenting with persistent respiratory symptoms in high-risk populations. Issues of contact tracing and adherence were also a problem in this population.

Functional characterization of a composite bacteriocin locus from malt isolate Lactobacillus sakei 5.

Lactobacillus sakei 5, isolated from malted barley, produces three bacteriocins. Genetic and functional analysis of the purified bacteriocins showed that this strain produces a plasmid-encoded bacteriocin that is identical to sakacin P, as well as two novel, chromosomally encoded bacteriocins, which were designated sakacin T and sakacin X. The structural genes specifying sakacin T and sakacin X are part of the sakacin TX locus, which consists of two adjacent but divergently oriented gene clusters. The first gene cluster includes stxP, stxR, stxK, and stxT, which, based on functional and comparative sequence analysis, are believed to encode an inducing peptide and proteins involved in regulation and secretion of these bacteriocins. The second gene cluster includes the structural and immunity genes for sakacin T, a class IIb two-peptide bacteriocin composed of SakTalpha and SakTbeta, and sakacin X, a class IIa bacteriocin. Interestingly, a so-called transport accessory protein was absent from the locus, and based on our results it appears that a dedicated accessory protein is not required for processing and transport of sakacin T and sakacin X.