In silico exploration of Red Sea Bacillus genomes for natural product biosynthetic gene clusters

Background: The increasing spectrum of multidrug-resistant bacteria is a major global public health concern, necessitating discovery of novel antimicrobial agents. Here, members of the genus Bacillus are investigated as a potentially attractive source of novel antibiotics due to their broad spectrum of antimicrobial activities. We specifically focus on a computational analysis of the distinctive biosynthetic potential of Bacillus paralicheniformis strains isolated from the Red Sea, an ecosystem exposed to adverse, highly saline and hot conditions. Results: We report the complete circular and annotated genomes of two Red Sea strains, B. paralicheniformis Bac48 isolated from mangrove mud and B. paralicheniformis Bac84 isolated from microbial mat collected from Rabigh Harbor Lagoon in Saudi Arabia. Comparing the genomes of B. paralicheniformis Bac48 and B. paralicheniformis Bac84 with nine publicly available complete genomes of B. licheniformis and three genomes of B. paralicheniformis, revealed that all of the B. paralicheniformis strains in this study are more enriched in nonribosomal peptides (NRPs). We further report the first computationally identified trans-acyltransferase (trans-AT) nonribosomal peptide synthetase/polyketide synthase (PKS/ NRPS) cluster in strains of this species. Conclusions:B. paralicheniformis species have more genes associated with biosynthesis of antimicrobial bioactive compounds than other previously characterized species of B. licheniformis, which suggests that these species are better potential sources for novel antibiotics. Moreover, the genome of the Red Sea strain B. paralicheniformis Bac48 is more enriched in modular PKS genes compared to B. licheniformis strains and other B. paralicheniformis strains. This may be linked to adaptations that strains surviving in the Red Sea underwent to survive in the relatively hot and saline ecosystems

Strongyloses ratti and S. stercoralis: effects of cambendazole, thiabendazole and mebendazole in vitro

The effects of in vitro incubation of three henzimidazole anthelmintics, thiabendazole, mebendazole and cambendazole on Strongyloides were compared. No drug affected hatching of S. ratti eggs or the viability of infective larvae or parasitic adult worms, but all three inhibited moulting of S. ratti larvae. In addition, cambendazole, but not thiabendazole or mebendazole, impaired the viability of S. ratti first- and second-stage larvae. The three drugs had no effect on isolated S. stercorais free-living adult worms, but they all prevented development of S. stercoralis rhabditiform larvae. Thiabendazole and mebendazole had no effect on the infectivity of either S. ratti or S. stercoralis infective larvae, but infection with these worms was abrogated by prior incubation with cambendazole. These results indicate that cambendazole acts in a different manner to the other two drugs. Since it is active against larvae migrating through the tissues, it is potentially of much greater value than thiabendazole or mebendazole in the therapy of strongyloidiasis

Bacterial nanocellulose production from carbon dioxide

Conferencia invitada presentada en: 5th International Symposium on Bacterial Cellulose. Jena Alemania, 22-23 septiembre (2022)Carbon dioxide, the primary greenhouse gas emitted by human activity, is the pollutant that most influences global warming and the consequent climate change. CO2 capture and utilization, and when possible its further valorization, is proposed as a powerful technological strategy to alleviate the problem of greenhouse gas accumulation. We have isolated a bacterial strain able to produce cellulose when growing with naphthalene as sole carbon source [1, 2]. The strain belongs to the sulphur oxidizing bacteria and can also use a number of compounds and residues as carbon source to produce cellulose. We show that the strain can grow and produce cellulose when growing with carbon dioxide as sole carbon source and reduced sulphur compounds as source of reducing power. The cellulose biofilm is produced in thin parallel layers under static conditions, and forms ball-shaped aggregates at different shaking speeds. The produced polymer has all the characteristics of bacterial nanocellulose, namely 60 nm wide - several µM long fibres, with a typical cellulose FTIR spectrum. Analysis of the strain¿s genome identified a bcs cluster for cellulose synthesis. Knock-out mutants in bcsA or bcsK genes were capable of growth with carbon dioxide, but did not produce cellulose. The genome included the gene complements for a complete Calvin-Benson-Bassham cycle for CO2 fixation and for two pathways (sor and sox) for sulphur compound oxidation. However, a cbbL mutant in the RuBisCO large subunit gene was still capable of growth with carbon dioxide, suggesting the functioning of an alternative carbon fixation pathway. A spontaneous mutant with an increased capacity of cellulose production was isolated. We identified a large chromosomal deletion in the mutant genome that included, among others, the genes for a quorum sensing regulation system. Site-directed knock-out mutants in different genes of the QS system also showed increased levels of cellulose biosynthesis. The optimum conditions for cellulose production from CO2 are being established. The bacterial nanocellulose produced can be mechanically functionalized, with the potential for CO2 capture to reach levels above those presented for other conventional and non-renewable materials.This study was supported by the European Regional Development Fund FEDER, grant PY20_00328 from the Economic Transformation, Industry, Knowledge and University Council of the Junta de Andalucía, and grant PID2020-113144RB-I00 funded by MCIN/AEI/ 10.13039/501100011033