Biomedical subjects

Brunella Perito

Publications and source records attributed to Brunella Perito.

5 recordsLinked to original sources

PubMed2006

Bacillus subtilis gene cluster involved in calcium carbonate biomineralization.

Calcium carbonate precipitation, a widespread phenomenon among bacteria, has been investigated due to its wide range of scientific and technological implications. Nevertheless, little is known of the molecular mechanisms by which bacteria foster calcium carbonate mineralization. In our laboratory, we are studying calcite formation by Bacillus subtilis, in order to identify genes involved in the biomineralization process. A previous screening of UV mutants and of more than one thousand mutants obtained from the European B. subtilis Functional Analysis project allowed us to isolate strains altered in the precipitation phenotype. Starting from these results, we focused our attention on a cluster of five genes (lcfA, ysiA, ysiB, etfB, and etfA) called the lcfA operon. By insertional mutagenesis, mutant strains carrying each of the five genes were produced. All of them, with the exception of the strain carrying the mutated lcfA operon, were unable to form calcite crystals. By placing transcription under IPTG (isopropyl-beta-d-thiogalactopyranoside) control, the last gene, etfA, was identified as essential for the precipitation process. To verify cotranscription in the lcfA operon, reverse transcription-PCR experiments were performed and overlapping retrocotranscripts were found comprising three adjacent genes. The genes have putative functions linked to fatty acid metabolism. A link between calcium precipitation and fatty acid metabolism is suggested.

Bacillus subtilis↗

PubMed2006

Dominulin A and B: two new antibacterial peptides identified on the cuticle and in the venom of the social paper wasp Polistes dominulus using MALDI-TOF, MALDI-TOF/TOF, and ESI-ion trap.

Two new antibacterial peptides, denominated as Dominulin A and B, have been found on the cuticle and in the venom of females of the social paper wasp Polistes dominulus. The amino acidic sequence of the two peptides, determined by mass spectrometry, is INWKKIAE VGGKIL SSL for Dominulin A (MW = 1854 Da) and INWKKIAEIGKQVL SAL (MW = 1909 Da) for Dominulin B. Their presence on the cuticle was confirmed using MALDI-TOF by means of micro-extractions and direct analyses on body parts. The presence in the venom and the primary structure of the dominulins suggest their classification in the mastoparans, a class of peptides found in the venom of other Aculeate hymenoptera. Their antimicrobial action against Gram+ and Gram- bacteria fits in the range of the best natural antimicrobial peptides. Dominulins can represent an important defense of the colony of Polistes dominulus against microbial pathogens.

Amino Acid Sequence↗

PubMed2004

Growth phase-dependent expression of an endoglucanase encoding gene (eglS) in Streptomyces rochei A2.

Different growth phases of Streptomyces rochei A2, a cellulolytic strain isolated from termite gut, were determined in liquid culture. The strain exhibited a multiphasic growth curve typical of streptomycetes. In S. rochei A2, the secreted endoglucanase EglS is coded by a TTA-containing gene, conserved in other Streptomyces. The onset of S. rochei A2 eglS gene expression was determined by RT-PCR using total RNA extracted at different growth phases. The eglS gene was expressed only during transition, second rapid growth and stationary phases, the timing of expression being transcriptionally regulated.

Cell Division↗

PubMed2003

Characterization of bacterial pectinolytic strains involved in the water retting process.

Pectinolytic microorganisms involved in the water retting process were characterized. Cultivable mesophilic anaerobic and aerobic bacteria were isolated from unretted and water-retted material. A total of 104 anaerobic and 23 aerobic pectinolytic strains were identified. Polygalacturonase activity was measured in the supernatant of cell cultures; 24 anaerobic and nine aerobic isolates showed an enzymatic activity higher than the reference strains Clostridium felsineum and Bacillus subtilis respectively. We performed the first genotypic characterization of the retting microflora by a 16S amplified ribosomal DNA restriction analysis (ARDRA). Anaerobic isolates were divided into five different groups, and the aerobic isolates were clustered into three groups. 84.6% of the anaerobic and 82.6% of the aerobic isolates consisted of two main haplotypes. Partial 16S rRNA gene sequences were determined for 12 strains, representative of each haplotype. All anaerobic strains were assigned to the Clostridium genus, whereas the aerobic isolates were assigned to either the Bacillus or the Paenibacillus genus. Anaerobic isolates with high polygalacturonase (PG) activity belong to two clearly distinct phylogenetic clusters related to C. acetobutylicum-C. felsineum and C. saccharobutylicum species. Aerobic isolates with high PG activity belong to two clearly distinct phylogenetic clusters related to B. subtilisT and B. pumilusT.

Bacillus↗

PubMedDate not supplied

[Compulsory and additional parameters in water control].

The authors have analyzed 22 water samples from the Arno River (both river and drinking samples), as well as 11 effluent samples from an urban plant. Chemical and microbiological features of river samples were in line with the A3 class, needing treatment for drinking use (Executive Order n. 152/99); drinkable water met requirements (Presidents Decree n degrees 236/1988 and Executive Order n degrees 31/2001). As regards chemical parameters, effluents complied with the law (Executive Order n. 152/1999) but their bacteriological figures exceeded the standards set by the Authorities due to a lack in chlorination. Enteric viruses reacted to the RT-PCR test in 5 of the samples, including a Coxsackievirus Type B2 and a Poliovirus. No association was shown between bacteriophage parameters and virus.

English Abstract↗