Impact of Algicidal Bacillus mycoides on Diatom Ulnaria acus from Lake Baikal

Algae–bacteria interactions play an important role in water ecosystems. In this work, the BS2-15 algicidal strain was isolated from the bottom sediments of Lake Baikal and identified as Bacillus mycoides on the basis of 16S rDNA sequencing, its described ultrastructure, and biochemical properties. B. mycoides BS2-15 was demonstrated to have a strong algicidal effect against a freshwater diatom culture of Ulnaria acus, inhibiting its growth and increasing frustules fragility. By analyzing the impact of bacterial filtrate onto the cells of U. acus, we demonstrated that perhaps an algicidal compound is produced by bacteria independently in the presence of diatoms in a medium. Using methods of TUNEL and confocal microscopy, we revealed that the bacterial algicidal effect on the diatom cells results in DNA fragmentation, nucleus destruction, and neutral lipid accumulation. This phenomenon highlights the complexity of algae–bacteria interactions and their potential role in regulating water ecosystem microbial populations.

In vitro algicidal effect of polypyrrole on Prototheca species isolates from bovine mastitisAlgicidal activity of polypyrrole on Prototheca spp.

Algae of the genus Prototheca are microorganisms involved in the occurrence of diseases in humans and animals. In bovine species, Prototheca spp. cause environmental mastitis, productive losses in dairy herds, mainly leading to the discard of infected cows. Currently, there are no effective anti-Prototheca spp. drugs to combat this infection. Thus, the search for an efficacious therapy for Prototheca spp. infections have become essential. Highly soluble polypyrrole (Ppy) is a molecule with known antimicrobial activity. This study aimed to characterize Prototheca spp. isolates from bovine mastitis as well as to evaluate the susceptibility profile and to verify the morphological alterations on Prototheca spp. isolates treated with Ppy. In this research, 36 Brazilian isolates of Prototheca spp. were characterized by restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) assay for the mitochondrial cytB gene. Additionally, Ppy algicidal activity against these isolates of Prototheca spp. was assessed by minimal microbicidal concentration method in microplates. Further, scanning electron microscopy (SEM) was performed in order to verify the morphological alterations on Prototheca spp. isolates in response to Ppy. The isolates were characterized as belonging to Prototheca zopfii genotype 2 (35/36) and Prototheca blaschkeae (1/36). Ppy had an algicidal effect on all isolates tested at concentrations ranging from 15.625 μg ml−1 to 62.5 μg ml−1. SEM showed changes on planktonic and sessile P. zopfii, including a decrease of the number of cells with the presence of an amorphous substance involving the cells. The algicidal activity of Ppy suggests the therapeutic potential of this molecule in the prevention and treatment of Prototheca spp. in bovine mastitis.

Roofing granules with additive of copper-zinc powder having biocidal properties

Introduction. In the world practice, ceramic coated roofing granules with various biocidal (algicidal) additives are used to prevent discoloration of asphalt roofing shingle. The paper propose the application of the selective dissolution of brass process to accelerate the algicidal effect of surface mineral granules. The authors show that incorporating of brass pigment in the color coat of roofing granules provides the desired degree of algae resistance over an extended period of time. Materials and methods. The brass pigment powder was taken as an algicidal additive. Algae resistant granules with the brass pigment were made in Stroymineral plant. Standard AR granules from North America market were taken as a control sample. Algicidal effect was measured by comparison of control sample and manufactured algae retardant granules performance in the 4 weeks quantitative spectrophotometric chlorophyll test. Measurement of an optical density of the liquid culture solution were made to determine the algae growth rates. The measurement was performed in the laboratory for the development of innovative medicines and biotechnologies in MIPT University. Results. The results show that manufactured algae retardant granules displayed level of the algicidal activity which is equal to control sample during the research. It was found that the highest algicidal activity was shown by products manufactured using finely dispersed copper-zinc alloy powder with a zinc content between 15-30 %. Conclusions. The manufactured granules with brass pigment in the color coating reveal ability to inhibit the algae growth.

Combined algicidal effect of urocanic acid,N-acetylhistamine andl-histidine to harmful algaPhaeocystis globosa

Ultrastructure ofPhaeocystis globosacells after treatment with EC50value for 72 h: (a) control, (b) ace (16 μg mL−1), (c) uro (8 μg mL−1), (d) uro + ace (1 : 1 TU, 8 : 16 μg mL−1) Chl, chloroplast; CW, cell wall; N, nucleus; PM, plasma membrane.