Antimycotoxigenic and antifungal activities of Citrullus colocynthis seeds against Aspergillus flavus and Aspergillus ochraceus contaminating wheat stored

Plant extracts and their constituents have a long history as antifungal agents, but their use in biotechnology as preservatives, due to the increasing resistance of fungi to fungicides, has been rarely reported. The aim of this study was to assess in vitro antifungal and antimycotoxigenic power of methanolic and aqueous extracts of Citrullus colocynthis seeds, an aromatic and medicinal plant, of Algerian flora, against two toxigenic species of the genera Aspergillus responsible of contamination of wheat stored. The antifungal and antimycotoxigenic activity of methanolic and aqueous extracts were screened against Aspergillus ochraceus and Aspergillus flavus. Dillution method was used to investigate the antimicrobial and antimycotoxigenic activity. These bioassays are preceded by a phytochemical screening. The phytochemical analysis of seeds extracts revealed the presence of some chemical groups (polyphenols, steroids and alkaloids) which can express the desired activities. The results suggest that the extracts showed a very good antifungal activity against A. ochraceus, but for A. flavus any antifungal activity was recorded. The extracts have good antiochratoxigenic power in liquid medium. This evaluation confirms that the extracts of C. colocynthis seeds used at low concentration may have significant potential for biological control of fungi and theirs toxins.Keywords: Citrullus colocynthis, methanolic extract, aqueous extract, phytochemical screening, antifungal activity, antimycotoxigenic activity, antiochratoxigenic activity

CRISPR-Cas systems as antimicrobial agents for agri-food pathogens

name of first author & corresponding author is: Gacem, Mohamed Amine (not Amine, Gacem Mohamed as indicated at publisher's page)The CRISPR-Cas (clustered regularly interspaced short palindromic repeat-CRISPR-associated sequences) systems identified in microorganisms are very diverse in their functional organization and mechanism. They participate in the illustration of the development of the strain that carries them over time. The reason is that each time an exogenous genetic fragment is encountered, a spacer is acquired and then inserted into the CRISPR array. These spacers can provide very important historical information on external aggressors, their ecology, and geography. This complex arrangement has a dynamic protection and defense capacity against exogenous genetic elements, which gives the bacterial cell better protection. On the genomic level, the understanding of its functional mechanism is a key factor in its exploitation as a molecular biology and genome editing tool. This chapter aims at clarifying the applications of the CRISPR/Cas system in the preservation and security of crops and food against viral, fungal, and bacterial alterations. © 2021 Elsevier Inc. All rights reserved.

Toxicology, biosynthesis, bio-control of aflatoxin and new methods of detection

Mycotoxins and their derivatives since their discoveries and until the present time are behind unspecified economic and medical damages. Aflatoxins are classified according to their physical–chemical and toxicological characters in the most dangerous row of the mycotoxins. These aflatoxins are in part responsible, of irreversible medical disasters that are not easily manageable such as cancer of the liver and kidneys, and in the other part, of losses in the stored cereal products. Based on these crucial findings, monitoring of this toxin became imperative in post-harvest food products, during storage, during transformation chain and even during the long phases of conservation. Vigilance of this toxin is delivered by detection methods using very advanced technologies to respond in the shortest possible times. In addition, the knowledge of factors supporting the biosynthesis of aflatoxins such as the temperature, moisture content, concentration of nitrogen and carbon, and the molecules responsible for the genetic control of the synthesis will be reflected later in the choice of bio-control techniques. This control is currently based on new strategies using the bioactives substances of the plants, the lactic bacteria and some strains of actinomycetes that have good inhibiting activity against aflatoxins with fewer side effects on Man. On the other hand, this brief review summarizes the results of new studies demonstrating the toxicity of the toxin, new detection methods and bio-control

RNAi-based system a new tool for insects’ control

One of the molecular devices practised recently has been the fusion of RNA interference (RNAi) into some agricultural products. It is a definite genetic controlling system recognized in eukaryotes. Through this system, certain exogenous pathogens are neutralized by deactivating the expression of target genes. The decisive factor for the progress of this gene defence machinery is the double-stranded RNA (dsRNA). The effectiveness and specificity of the RNAi tool in gene silencing have been approved with great precision in small-scale guide tests. The development of this molecular tool as bioinsecticides has started to attract the biotechnology industries. Once the safety and certainty actions respecting the regulatory framework are established by researchers and biotechnology industries for crop protection, for example, sustainability and particularity of defence, develop new resistant cultivars against plant pests, and removal of all unexpected effects on the environment, genetically modified crops incorporating dsRNA can be marketed. The current chapter discusses the RNAi tool and its role in protecting crops from insect pest attacks, dsRNA transfer methods in plant cells, and critical points affecting the achievement of the molecular tool. Finally, some environmental risks identified in the small-scale guide tests are discussed