Chunmei Jiang

Biological activity of lipopeptides from Bacillus

The lipopeptides of Bacillus are small metabolites that contain a cyclic structure formed by 7–10 amino acids (including 2–4 d-amino acids) and a beta-hydroxy fatty acid with 13–19 C atoms. These lipopeptides exhibit a variety of biological activities, including interactions with biofilms, and anti-fungal, anti-inflammatory, anti-tumor, anti-virus, and anti-platelet properties. The multiple activities of lipopeptides have stimulated significant interest in the exploitation of these lipopeptides for use as antibiotics, feed additives, anti-tumor agents, urgent thrombolytic therapeutic agents, and drug delivery systems. Understanding the natural function of these structurally diverse lipopeptides in Bacillus provides insight into microbial regulatory programs and is required for efficient development of more effective products. Currently, there is still insufficient knowledge of the direct target of these lipopeptides, and continued efforts are needed to enhance their biosynthesis efficiency for industrial applications.

Fungal silver nanoparticles: synthesis, application and challenges

Abstract Purpose: This paper aims to summarize recent developments regarding the synthesis, application and challenges of fungal AgNPs. Possible methods to overcome the challenge of synthesis and reduce the toxicity of AgNPs have been discussed. Materials and methods: This review consults and summary a large number of papers. Results: Silver nanoparticles (AgNPs) have great potential in many areas, as they possess multiple novel characteristics. Conventional methods for AgNPs biosynthesis involve chemical agents, causing environmental toxicity and high energy consumption. Fungal bioconversion is a simple, low-cost and energy-efficient biological method, which could successfully be used for AgNPs synthesis. Fungi can produce enzymes that act as both reducing and capping agents, to form stable and shape-controlled AgNPs. Conclusions: AgNPs have great potential in the medical and food industries, due to their antimicrobial, anticancer, anti-HIV, and catalytic activities. However, the observed in vitro and in vivo toxicity poses considerable challenges in the synthesis and application of AgNPs.

Strategies to increase the efficacy of using gut microbiota for the modulation of obesity.

Obesity is one of the most serious global public health challenges of the 21st century. The adjustment of gut microbiota is often recommended as an efficient strategy to treat obesity. This modulation of gut microbiota can be performed by many methods, including dietary intervention, antibiotic application, the use of prebiotics and probiotics, bariatric surgery and faecal microbiota transplantation. In most cases, positive effects have been observed in response to treatment, but invalid and even contrary effects have also been observed in some cases due to factors that are unrelated to intervention methods, such as genetic factors, patient age or gender, environmental microbiota, climate, geography and lifestyle. These factors can cause variation of gut microbial populations and thus should also be taken into consideration when selecting modulation strategies.

Lipopeptides from Bacillus subtilis have potential application in the winemaking process: inhibiting fungal and ochratoxin A contamination and enhancing esters and acids biosynthesis

Background and Aims Aspergillus carbonarius is considered the major cause of ochratoxin A (OTA) contamination in grape products, especially wine. The lipopeptides produced by Bacillus subtilis have been found to inhibit A. carbonarius contamination and OTA production in grapes. In order to assess the potential application of these lipopeptides during the winemaking process, they were tested alone or in combination with SO2 to evaluate their effect on fungal growth and OTA contamination. Methods and Results Lipopeptides at 200 and 400 mg/L were added alone or in combination with SO2 during the winemaking process using naturally contaminated grapes. Aspergillus carbonarius was also manually inoculated before fermentation to simulate grapes with a high fungal contamination and to investigate the inhibitory effect of lipopeptides on OTA-producing fungi. The lipopeptides inhibited significantly fungal contamination and OTA production, much stronger than SO2 against OTA-producing A. carbonarius, at an optimum level of 200 mg/L. Yeast growth and biosynthesis of esters and acids were also promoted by lipopeptides during winemaking, which led to an improvement of wine flavour. Conclusions Lipopeptides isolated from B. subtilis had a more potent inhibitory effect on fungal contamination and OTA accumulation than that of SO2 during winemaking. Moreover, lipopeptides had no negative effect on fermentation, wine composition and sensory attributes. Significance of the Study These findings highlight the interesting possibility for the application of lipopeptides to replace or reduce the amount of SO2 added during winemaking, especially when the inhibition of fungal contamination and OTA accumulation is considered.

Dietary compounds have potential in controlling atherosclerosis by modulating macrophage cholesterol metabolism and inflammation via miRNA

Atherosclerosis (AS) is a typical example of a widespread fatal cardiovascular disease. Accumulation of cholesterol-laden macrophages in the artery wall forms the starting point of AS. Increased influx of oxidized low-density lipoprotein to macrophages and decreased efflux of free cholesterol out of macrophages constitute major factors promoting the development of AS. Inflammation further aggravates the development of AS along or via interaction with the cholesterol metabolism. Many microRNAs (miRNAs) are related to the regulation of macrophage in AS in aspects of cholesterol metabolism and inflammation signaling. Dietary compounds perform AS inhibitory effects via miRNAs in the cholesterol metabolism (miR-19b, miR-378, miR-10b, miR-33a, and miR-33b) and two miRNAs in the inflammation signaling (miR-155 and miR-146a). The targeted miRNAs in the cholesterol metabolism vary greatly among different food compounds; however, in inflammation signaling, most food compounds target miR-155. Many receptors are involved in macrophages via miRNAs, including ABCA1 and ABCG1 as major receptors in the cholesterol metabolism, while nuclear factor-κB (NF-κB) and Nrf2 signaling and PI3K/AKT signaling pathways are targeted during inflammation. This article reviews current literature to investigate possible AS therapy with dietary compounds via targeting miRNAs. Currently existing problems were also discussed to guide further studies.

Iturin A-like lipopeptides from Bacillus subtilis trigger apoptosis, paraptosis, and autophagy in Caco-2 cells: ZHAO et al.

This study revealed that iturin A‐like lipopeptides produced by Bacillus subtillis induced both paraptosis and apoptosis in heterogeneous human epithelial colorectal adenocarcinoma (Caco‐2) cells. Autophagy was simultaneously induced in Caco‐2 cells treated with iturin A‐like lipopeptides at the early stage and inhibited at the later stage. A western blot analysis showed that the lipopeptides induced apoptosis in Caco‐2 cells via a mitochondrial‐dependent pathway, as indicated by upregulated expression of the apoptotic genes bax and bad and downregulated expression of the antiapoptotic gene bcl‐2. The induction of paraptosis in Caco‐2 cells was indicated by the occurrence of many cytoplasmic vacuoles accompanied by endoplasmic reticulum (ER) dilatation and mitochondrial swelling and dysfunction. ER stress also occurred with significant increases in reactive oxygen species and Ca2+ levels in cells. Autophagy was detected by a transmission electron microscopy analysis and by upregulated expression of LC3‐II and downregulated expression of LC3‐I. The inhibition of autophagy at the later stage was shown by upregulated expression of p62. This study revealed the capability of iturin A‐like B. subtilis lipopeptides to simultaneously execute antitumor potential via multiple pathways.

Fungal Spores Promote the Glycerol Production of Saccharomyces cerevisiae by Upregulating the Oxidative Balance Pathway

Fungal contamination is prevalent in grape berries and unavoidable during the winemaking process. In botrytized wine, Botrytis cinerea contamination of grape berries beneficially promotes the wine flavor, which is desirable especially with high glycerol content. To investigate the underlying mechanism, Aspergillus carbonarius and B. cinerea spores were separately cocultured with two different Saccharomyces cerevisiae strains in both grape juice and synthetic nutrient media. The results showed that both A. carbonarius and B. cinerea promoted glycerol accumulation and the consumption of sugars in the coculture systems but could not synthesize glycerol by themselves. The metabolites produced by fungal spores triggered these reactions. Reverse transcription-polymerase chain reaction analysis showed that the presence of A. carbonarius spores regulated the expression of GPP1 and GPD2, indicating that the reaction was triggered by regulating the oxidative balance pathway. The study revealed the beneficial impact of fungal contamination on wine quality by influencing yeast metabolism.

Production of bioproducts by endophytic fungi: chemical ecology, biotechnological applications, bottlenecks, and solutions

Endophytes are microorganisms that colonize the interior of host plants without causing apparent disease. They have been widely studied for their ability to modulate relationships between plants and biotic/abiotic stresses, often producing valuable secondary metabolites that can affect host physiology. Owing to the advantages of microbial fermentation over plant/cell cultivation and chemical synthesis, endophytic fungi have received significant attention as a mean for secondary metabolite production. This article summarizes currently reported results on plant-endophyte interaction hypotheses and highlights the biotechnological applications of endophytic fungi and their metabolites in agriculture, environment, biomedicine, energy, and biocatalysts. Current bottlenecks in industrial development and commercial applications as well as possible solutions are also discussed.