Cross-habitat distribution pattern of Bacillus communities and their capacities of producing industrial hydrolytic enzymes in Paracel Islands: Habitat-dependent differential contributions of the environment

Antibiofilm Power of Basil Essential Oil Against Fish-Originated Multidrug-Resistant Salmonella and Bacillus spp.: Targeting Biofilms on Food Contact Surfaces

The antimicrobial and antibiofilm efficacy of two Ocimum basilicum L., essential oils sourced from Colombia (BEOC) and Italy (BEOI), was evaluated against multidrug-resistant fish isolates of Salmonella enterica subsp. salamae, Bacillus thuringiensis, and Bacillus oceanisediminis-species for which such activity has not been previously reported. Using a fish-based model system (FBMS), we found that BEOI, rich in linalool (69.86%), exhibited stronger antimicrobial activity than camphor-dominated BEOC (24.61%). The antimicrobial effects of both EOs were strain- and concentration-dependent, with minimum bactericidal concentration (MBC) 3.75-15.0 µL/mL for BEOI and 15.0-30.0 µL/mL for BEOC. Pure linalool showed even greater potency (MBC: 0.0125 to 0.025 µL/mL). Confocal laser scanning microscopy revealed that BEOI induced severe membrane damage (27% of the cells within 1 h), ultimately leading to the death of 96% of the cells after 24 h. Biofilm formation, assessed in both FBMS and tryptone soy broth (TSB), was strain-dependent, with FBMS promoting higher biofilm production than TSB. Moreover, significant differences in biofilm morphotypes were observed, with the morphotype PDAR (pink dry and rough), characterized by only cellulose, being the most frequently exhibited by the strains (7/15), while BDAR (brown dry and rough), characterized by only curli, was the least expressed (7/15); the remaining strains presented morphotype RDAR. In addition, the strains in polystyrene surfaces accumulated more biomass than stainless steel 304. Notably, BEOI and linaool significantly reduced biofilm formation across all strains, with a reduction of 90% in S. enterica subsp. salamae strains (TJC19 and TJC21. These strains with the RDAR phenotype likely contribute to their strong biofilm-forming capacity. Our findings highlight BEOI's potential as a natural anti-biofilm agent in food processing environments, offering a promising strategy to combat multidrug-resistant bacteria biofilm-related challenges in the food industry.

Large-scale fermentation of Lactiplantibacillus pentosus 292 for the production of lactic acid and the storage strategy based on molasses as a preservative

BACKGROUND

Lactiplantibacillus pentosus 292 is a lactic acid bacterium (LAB) with significant probiotic potential, but large-scale production is often limited by high production costs and preservation challenges. This study aimed to develop a cost-effective medium to enhance lactic acid production and establish a feasible preservation strategy to support the strain's large-scale application.

RESULTS

A low-cost medium containing glucose, yeast powder, K₂HPO₄, and Tween-80 was formulated, enabling Lactiplantibacillus pentosus 292 to achieve a lactic acid yield of 16.24 g/L, representing an 83.48% increase compared to the traditional MRS medium. Fermentation kinetics models for bacterial growth, substrate consumption, and product generation were established in a 200-L fermenter using the Logistic, Luedeking-Piret-like, and Luedeking-Piret models, and the R2 values from the model equation were 0.9921 (OD600nm), 0.9942 (dry weight), 0.9506 (total protein), 0.8383 (lactic acid), 0.8898 (total sugar), and 0.8585 (reducing sugar), respectively, indicating that these models were suitable for accurately simulating the growth, nutrient production, and substrate consumption of L. pentosus 292. Additionally, a preservation strategy was developed by using 1-3% molasses as a preservative for the fermentation broth, and its efficacy was verified through temperature acceleration experiments.

CONCLUSION

In this work, a cost-effective medium that significantly increased lactic acid yield and a preservative based on molasses as a strategy to extend the storage period of fermentation products were developed for large-scale production of L. pentosus 292, a member of probiotic LAB. Additionally, large-scale fermentation kinetics models were constructed, providing valuable technical insights for the large-scale production and application of this LAB, highlighting its significant potential for industrial applications.

Chromolaena odorata affects soil nitrogen transformations and competition in tropical coral islands by altering soil ammonia oxidizing microbes

Invasive plants can change the community structure of soil ammonia-oxidizing microbes, affect the process of soil nitrogen (N) transformation, and gain a competitive advantage. However, the current researches on competition mechanism of Chromolaena odorata have not involved soil nitrogen transformation. In this study, we compared the microbially mediated soil transformations of invasive C. odorata and natives (Pisonia grandis and Scaevola taccada) of tropical coral islands. We assessed how differences in plant biomass and tissue N contents, soil nutrients, N transformation rates, microbial biomass and activity, and diversity and abundance of ammonia oxidizing microbes associated with these species impact their competitiveness. The results showed that C. odorata outcompeted both native species by allocating more proportionally biomass to aboveground parts in response to interspecific competition (12.92 % and 22.72 % more than P. grandis and S. taccada, respectively). Additionally, when C. odorata was planted with native plants, the available N and net mineralization rates in C. odorata rhizosphere soil were higher than in native plants rhizosphere soils. Higher abundance of ammonia-oxidizing bacteria in C. odorata rhizosphere soil confirmed this, being positively correlated with soil N mineralization rates and available N. Our findings help to understand the soil N acquisition and competition strategies of C. odorata, and contribute to improving evaluations and predictions of invasive plant dynamics and their ecological effects in tropical coral islands.

Metabolic picture of microbial interaction: chemical crosstalk during co-cultivation between three dominant genera of bacteria and fungi in medicinal plants rhizosphere

INTRODUCTION

Microbial communities affect several aspects of the earth's ecosystem through their metabolic interaction. The dynamics of this interaction emerge from complex multilevel networks of crosstalk. Elucidation of this interaction could help us to maintain the balance for a sustainable future.

OBJECTIVES

To investigate the chemical language among highly abundant microbial genera in the rhizospheres of medicinal plants based on the metabolomic analysis at the interaction level.

METHODS

Coculturing experiments involving three microbial species: Aspergillus (A), Trichoderma (T), and Bacillus (B), representing fungi (A, T) and bacteria (B), respectively. These experiments encompassed various interaction levels, including dual cultures (AB, AT, TB) and triple cultures (ATB). Metabolic profiling by LC-QTOFMS revealed the effect of interaction level on the productivity and diversity of microbial specialized metabolites.

RESULTS

The ATB interaction had the richest profile, while the bacterial profile in the monoculture condition had the lowest. Two native compounds of the Aspergillus genus, aspergillic acid and the dipeptide asperopiperazine B, exhibited decreased levels in the presence of the AT interaction and were undetectable in the presence of bacteria during the interaction. Trichodermarin N and Trichodermatide D isolated from Trichoderma species exclusively detected during coexistence with bacteria (TB and ATB). These findings indicate that the presence of Bacillus activates cryptic biosynthetic gene clusters in Trichoderma. The antibacterial activity of mixed culture extracts was stronger than that of the monoculture extracts. The TB extract exhibited strong antifungal activity compared to the monoculture extract and other mixed culture treatments.

CONCLUSION

The elucidation of medicinal plant microbiome interaction chemistry and its effect on the environment will also be of great interest in the context of medicinal plant health Additionally, it sheds light on the content of bioactive constituents, and facilitating the discovery of novel antimicrobials.

Ecology and resistance to UV light and antibiotics of microbial communities on UV cabins in the dermatology service of a Spanish hospital

Microorganisms colonize all possible ecological habitats, including those subjected to harsh stressors such as UV radiation. Hospitals, in particular the UV cabins used in phototherapy units, constitute an environment in which microbes are intermittently subjected to UV irradiation. This selective pressure, in addition to the frequent use of antibiotics by patients, may represent a threat in the context of the increasing problem of antimicrobial resistance. In this work, a collection of microorganisms has been established in order to study the microbiota associated to the inner and outer surfaces of UV cabins and to assess their resistance to UV light and the antibiotics frequently used in the Dermatology Service of a Spanish hospital. Our results show that UV cabins harbor a relatively diverse biocenosis dominated by typically UV-resistant microorganisms commonly found in sun-irradiated environments, such as Kocuria, Micrococcus or Deinococcus spp., but also clinically relevant taxa, such as Staphylococcus or Pseudomonas spp. The UV-radiation assays revealed that, although some isolates displayed some resistance, UV is not a major factor shaping the biocenosis living on the cabins, since a similar pool of resistant microorganisms was identified on the external surface of the cabins. Interestingly, some Staphylococcus spp. displayed resistance to one or more antibiotics, although the hospital reported no cases of antibiotic-resistance infections of the patients using the cabins. Finally, no association between UV and antibiotic resistances was found.

Marine enzymes: Classification and application in various industries

Oceans are regarded as a plentiful and sustainable source of biological compounds. Enzymes are a group of marine biomaterials that have recently drawn more attention because they are produced in harsh environmental conditions such as high salinity, extensive pH, a wide temperature range, and high pressure. Hence, marine-derived enzymes are capable of exhibiting remarkable properties due to their unique composition. In this review, we overviewed and discussed characteristics of marine enzymes as well as the sources of marine enzymes, ranging from primitive organisms to vertebrates, and presented the importance, advantages, and challenges of using marine enzymes with a summary of their applications in a variety of industries. Current biotechnological advancements need the study of novel marine enzymes that could be applied in a variety of ways. Resources of marine enzyme can benefit greatly for biotechnological applications duo to their biocompatible, ecofriendly and high effectiveness. It is beneficial to use the unique characteristics offered by marine enzymes to either develop new processes and products or improve existing ones. As a result, marine-derived enzymes have promising potential and are an excellent candidate for a variety of biotechnology applications and a future rise in the use of marine enzymes is to be anticipated.