Microorganism Genetics Laboratory

Ricerca al DBB

Referent: Dr. Cinzia Calvio

Co-worker: Valeria Bontà

The Microorganism Genetics Laboratory works mainly on the model organism for Gram-positive Bacillus subtilis bacteria. B. subtilis, in addition to being a paradigm for microbial genetics, represents a perfect host for the production of recombined enzymes. Due to its characteristics it is already highly exploited in various biotechnological sectors, even at an industrial level.

Bacillus subtilis IN THE CHALLENGES OF SUSTAINABLE DEVELOPMENT

In partnership with:

  • Dr. Maurizia Dossena, Daniela Buonocore and EnricoDoria (DBB-Unipv and spin-off BIORESTART-Unipv) (recovery of nutraceutical compounds from food waste)
  • Proff. Stefania Colombini and Gianluca Galassi (Dipartimento di Scienze Agrarie e Ambientali, Università degli Studi di Milano) (improvement of the nutrition of dairy cattle)
  • Proff. Alma Balestrazzi and Anca Macovei (DBB-Unipv and consorzio internazionale BenefitMED (sustainable agriculture)
  • Prof. Marcin Łukaszewicz (Dipartimento di biotrasformazioni, Università di Breslavia and InventionBio, Polonia).

Bacillus subtilis is a soil bacterium with numerous beneficial characteristics. Living in the soil, it is naturally equipped with metabolic pathways that make it capable of degrading plant biomass, contributing to the recycling of nutrients; moreover, it favors the development of plants, improving agricultural productivity. It grows well in the laboratory on a wide variety of substrates, can be easily engineered and is a perfect host for the production of degradative enzymes and other bioproducts useful to humans.In the microorganism genetics laboratory we deal with the improvement of the beneficial characteristics of B. subtilis for use in improving the environmental sustainability of many agro-industrial processes. Here are some examples of research currently underway

  1. By optimizing the productivity of enzymes that degrade plant biomass, we are able to obtain bacterial strains that favor the extraction of compounds of nutraceutical interest from plant waste (Doria et al, 2022).
  2. Optimized strains, grown on waste biomass such as rice straw, can improve the nutritional value of some forages used in feeding dairy cows, making them an excellent ally in the livestock industry.
  3. Over-producing strains of the natural polymer γ-PGA can positively affect the germination of seeds in arid soils. Together with the Plant Physiology group, we have created an international partnership which, starting from legume species highly resilient to climate change, aims to develop innovative technologies of sustainable agriculture, based on seed priming treatments with the use of Bacillus strains able to improve seed vigor and crop performance in adverse weather conditions.
  4. The γ-PGA polymer has unique characteristics that make it an ideal product for the cosmetics industry, and can be produced in a sustainable manner from waste biomass. Thanks to a collaboration with the University of Wroclaw and the InventionBio industrial biorefinery, both in Poland, we have access to systems for the industrial scale-up of microbial fermentation and sophisticated tools for the characterization of products and fermentation processes.

 

Γ-PGA-SPECIFIC HYDROLASE AS ANTIBACTERIAL AGENTS

In partnership with:

  • C. Morelli del Dip. di Chimica (Università Statale di Milano).

We identified and characterized four new genes in B. subtilis that encode γ-PGA hydrolase. Abbiamo scoperto che questi geni, di origine fagica, si sono diffusi in numerose specie batteriche, tra cui alcuni patogeni, attraverso processi di trasferimento genico orizzontale (Mamberti et al, 2015; Ramaswamy et al, 2018). We are characterizing the enzymatic activity and substrate specificity of these enzymes in order to be able to use them as antibacterial agents against pathogens in which γ-PGA represents a virulence factor.

 

BIOLOGICAL ROLE OF SwrA, REGULATING PROTEIN OF Bacillus subtilis WITH UNKNOWN FUNCTION

In Bacillus subtilis the two-component DegS-DegU system is a central regulator that controls the expression of more than one hundred genes involved in the transition from the exponential to stationary growth phase, coordinates the differentiation of single cells in multicellular communities and, in bacteria pathogens such as Listeria monocytogenes or Bacillus anthracis, is involved in virulence. Together with the SwrA protein, which does not belong to any known protein class, DegU complexly regulates a number of other behaviors in B. subtilis (Mordini et al, 2013; Ermoli et al, 2021). We are analyzing in more detail the effect, recently discovered, of SwrA on some of the genetic pathways controlled by DegU and we are investigating some peculiarities that characterize the swrA locus, to understand the functioning pattern of this extremely complex and still unknown genetic system.