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Methicillin-resistant Staphylococcus aureus (MRSA) is drug-resistant and biofilm-forming pathogenic bacteria with severe morbidity and mortality, and has been continuously detected in food products in recent years. Mannosylerythritol lipids (MELs) are novel biosurfactants and perform antibacterial property against gram-positive bacteria. Ultrasound has been applied into food sterilization as non-thermal techniques and has advantage of maintaining food nutrition and flavor over heat pasteurization. In this work, the synergistic treatment of ultrasound and MEL-A was used to combat planktonic cells and biofilm of MRSA. As a result, the combined treatment has exhibited remarkable antibacterial effect proved by enumeration of viable microbes. Furthermore, flow cytometry, scanning electron microscopy and transmission electron microscopy revealed ultrasound has enhanced the inhibitory effect of MEL-A through exacerbating cell membrane damage. On the other hand, the collaborating working modes to eradicate MRSA biofilm were disturbing cell adhesion to surface by MEL-A and destructing mature biofilm mechanically by ultrasound, reaching to over 90% of clearance rate. The findings of this study illustrated the synergistic antimicrobial mechanism of ultrasound and MEL-A treatments, and offered theoretical basis for their potential applications in food preservation., (Copyright © 2020 The Author(s). Published by Elsevier B.V. All rights reserved.)

Agaricus bitorquis (Quél.) Sacc. Chaidam (ABSC), is a kind of rare edible macrofungi with a variety of biological ingredients, especially its polysaccharides. However, the low yield limits the popularity and promotion of rare edible macrofungi as well as its macrofungi polysaccharides. Hence, developing a positive and effective cultivation method is of great importance. Herein, an efficient ultrasonic (US) stimulation strategy was developed to improve mycelial growth and exopolysaccharides (EPS) biosynthesis from ABSC in submerged cultivation without light. A time design was employed to illustrate the effect of various process parameters including duration, starting point and times of US irradiation on ABSC productivity. 5 min US treatment for once upon ABSC after fermentation for 48 h could significantly improve EPS production and mycelia growth by above 26% and 15.03%, respectively. Furthermore, six times of 5 min US treatment could make the amount of EPS reach 218.78 ± 17.09 mg/g, which was 2.52-fold higher than that of the control. Moreover, the enhanced effect induced by US was further expounded by fermentation kinetics. Besides, the US treatment could increase mycelia permeability, change structure and reduce mycelial diameter to promote mass transfer, resulting in the improvement of EPS production and mycelia accumulation. The results demonstrated that the present proposed US intensification approach could be useful to boost up the fermentation of ABSC, which possibly applied to yield increase and fermentation product acquisition of macrofungi., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)