Algicidal activity of a novel indigenous bacterial strain of Paracoccus homiensis against the harmful algal bloom species, Karenia mikimotoi.

Harmful algal blooms have deleterious effects on aquatic ecosystems and human health. The application of algicidal bacteria is a promising and environmentally friendly method of preventing and eradicating harmful algal blooms. In this study, a screen for algicidal agents against harmful algal blooms was used to identify an algicidal bacterial strain (strain O-4) isolated from a Karenia mikimotoi culture. Strain O-4 exhibited a strong inhibitory effect on harmful K. mikimotoi and was identified as Paracoccus homiensis via 16S rRNA gene sequence analysis. This strain killed K. mikimotoi by secreting active algicidal compounds, which were stable at temperatures of -80-121 °C but were sensitive to strongly acidic conditions (pH = 2). The algicidal properties of strain O-4 against K. mikimotoi were cell density- and time-dependent. No significant changes or negative effects were noted for two other Chlorophyta species, which highlighted the specificity of the studied algicidal substance. Finally, single-factor experiments revealed the optimum growth conditions of strain O-4 under different pH and temperature conditions. Therefore, strain O-4 has the potential to be used as a bio-agent for reducing the biomass of harmful K. mikimotoi blooms.

[Main hypotheses on mechanisms underlying plant invasion: A review.] / æ¤ç‰©å ¥ä¾µæœºåˆ¶çš„ä¸»è¦å‡è¯´.

Plant invasion is one of the most serious global problems, destroying ecosystem structure and function. With the severity of plant invasion, it is particularly important to understand the mechanisms of plant invasion in order to control and solve the problem. We summarized different mechanisms of plant invasion and the synergy among them, expounded the allelopathy, the plant-soil feedbacks, the reciprocal symbiosis, the effects of plant functional traits and phenotype plasticity in the process of plant invasion, and comprehensively analyzed the synergy of multiple mechanisms on plant invasion trajectory. According to the results, the invasion trajectory of alien plants in the invasive site was divided into four stages: introduction, colonization, establishment, and invasion. Integrating all kinds of obstacles and promoting factors encountered into it and putting forward the invasion curve of plants would contribute to the future research and management of invasive plants. We further highlighted the current research deficiencies and future research directions and objectives based on analyzing current research methods of plant invasion.