Genome engineering reveals large dispensable regions in Bacillus subtilis.

Bacterial genomes contain 250 to 500 essential genes, as suggested by single gene disruptions and theoretical considerations. If this view is correct, the remaining nonessential genes of an organism, such as Bacillus subtilis, have been acquired during evolution in its perpetually changing ecological niches. Notably, approximately 47% of the approximately 4,100 genes of B. subtilis belong to paralogous gene families in which several members have overlapping functions. Thus, essential gene functions will outnumber essential genes. To answer the question to what extent the most recently acquired DNA contributes to the life of B. subtilis under standard laboratory growth conditions, we initiated a "reconstruction" of the B. subtilis genome by removing prophages and AT-rich islands. Stepwise deletion of two prophages (SPbeta, PBSX), three prophage-like regions, and the largest operon of B. subtilis (pks) resulted in a genome reduction of 7.7% and elimination of 332 genes. The resulting strain was phenotypically characterized by metabolic flux analysis, proteomics, and specific assays for protein secretion, competence development, sporulation, and cell motility. We show that genome engineering is a feasible strategy for functional analysis of large gene clusters, and that removal of dispensable genomic regions may pave the way toward an optimized Bacillus cell factory.

The concept of maintenance physiotherapy.

This paper explores the concept of maintenance physiotherapy. Firstly, a consensus definition of maintenance physiotherapy is proposed following consultation with 11 senior physiotherapists throughout Australasia. This consensus definition is compared retrospectively with a definition of maintenance physiotherapy given in response to interview of 91 physiotherapists treating non-catastrophically injured motor vehicle patients more than five years post-accident (treating physiotherapists). Comparison was made by distilling the experts' definition into nine check points and scoring definitions given by the treating physiotherapists against these nine points. The results demonstrated a concurrence between the two groups of between zero and seven with a median of four. This paper supports maintenance physiotherapy as an accepted treatment form. To adhere more closely to the consensus definition of maintenance physiotherapy, treating physiotherapists should consider referral to non-physiotherapy alternatives, to ensure all possible treatment options are exhausted before the rehabilitation phase is complete. In addition, current objective outcome measures to justify and measure continued treatment should be used regularly. Patient education, consistent clinical diagnosis and categorisation of long-term patient groups should be more fully incorporated into the practice of maintenance physiotherapy. The paper aims to provide a reference from which the concept of maintenance physiotherapy can evolve.