Expression of the fibronectin-binding components of Streptococcus pyogenes in Escherichia coli demonstrates that they are proteins

The fibronectin-binding components (fbcs) of two clinical isolates and a culture collection strain of Streptococcus pyogenes have been analysed. Western immunoblotting of bacterial lysates which had been fractionated on polyacrylamide gels revealed trypsin-sensitive fibronectin-binding species. The genes specifying the fbcs were cloned from all three strains and expressed in Escherichia coli using a lambda EMBL3 vector. An fbc gene from the culture collection strain was subcloned and expressed in the E. coli expression vector pJLA601, and subjected to deletion analysis. The fibronectin-binding domain was thereby localized within a 40 kDa truncated peptide encoded by the 1000 bp C-terminal region of the gene. Southern hybridization experiments demonstrated that the analysed gene was present in the parental S. pyogenes chromosome, but not in the DNA of fbc expressing lambda clones obtained from the two clinical isolates. Further evidence for the existence of at least two different types of fbcs in group A streptococci was provided by Western blot analysis of recombinant phage lysates which revealed a complex series of fibronectin-binding species ranging from 120 to 200 kDa in size and showing strain-dependent variation in their patterns. As was the case with parental streptococcal strains all of the recombinant fbcs were protease-sensitive, and treatment with trypsin or pronase resulted in a total loss of fibronectin-binding activity. Competitive inhibition experiments indicated that lipoteichoic acid was not a significant fbc in the tested streptococcal strains.(ABSTRACT TRUNCATED AT 250 WORDS)     

The darkest microbiome—a post-human biosphere

Microbial technology is exceptional among human activities and endeavours in its range of applications that benefit humanity, even exceeding those of chemistry. What is more, microbial technologists are among the most creative scientists, and the scope of the field continuously expands as new ideas and applications emerge. Notwithstanding this diversity of applications, given the dire predictions for the fate of the surface biosphere as a result of current trajectories of global warming, the future of microbial biotechnology research must have a single purpose, namely to help secure the future of life on Earth. Everything else will, by comparison, be irrelevant. Crucially, microbes themselves play pivotal roles in climate (Cavicchioli et al., Nature Revs Microbiol 17 : 569–586, 2019). To enable realization of their full potential in humanity’s effort to survive, development of new and transformative global warming-relevant technologies must become the lynchpin of microbial biotechnology research and development. As a consequence, microbial biotechnologists must consider constraining their usual degree of freedom, and re-orienting their focus towards planetary-biosphere exigences. And they must actively seek alliances and synergies with others to get the job done as fast as humanly possible; they need to enthusiastically embrace and join the global effort, subordinating where necessary individual aspirations to the common good (the amazing speed with which new COVID-19 diagnostics and vaccines were developed and implemented demonstrates what is possible given creativity, singleness of purpose and funding). In terms of priorities, some will be obvious, others less so, with some only becoming revealed after dedicated effort yields new insights/opens new vistas. We therefore refrain from developing a priority list here. Rather, we consider what is likely to happen to the Earth’s biosphere if we (and the rest of humanity) fail to rescue it. We do so with the aim of galvanizing the formulation and implementation of strategic and financial science policy decisions that will maximally stimulate the development of relevant new microbial technologies, and maximally exploit available technologies, to repair existing environmental damage and mitigate against future deterioration.