Chemical and biological evaluation of biosurfactant fractions from Wickerhamomyces anomalus CCMA 0358.

Biosurfactants (BS) are becoming a solution for today's world since they are considered a reasonable and eco-friendly option for use in products that require surfactants. This study aimed to evaluate the antibacterial activity of purified fractions containing biosurfactants produced by the yeast Wickerhamomyces anomalus CCMA 0358 using waste cooking oil (WCO) as substrate. Mixed fractions were separated and characterized by TLC, MPLC, GC-MS, LC-OMS, LC-SQMS, FTIR, 1H, 13C, DEPT 135, COSY, HSQC, and HMBC. The results confirmed the presence of palmitic acid and oleic acid fatty acids, derived from the core biosurfactant structure; however, the core could not be identified. The crude biosurfactant and its purified fractions were evaluated against pathogenic bacteria, and the purified fractions of the biosurfactant are more efficient at inhibitory and bactericidal activities than the crude biosurfactant. To the best of our knowledge, this is the first study that evaluated the antimicrobial activity of purified fractions of biosurfactants produced by the species Wickerhamomyces anomalus. Therefore, the purification of biosurfactants can emerge as an interesting alternative to increase the bioactivity of the compounds and ensure greater efficiency and biotechnological employability. KEY POINTS: • Successful production of a biosurfactant using a renewed carbon source. • Evaluation of the antimicrobial activity of purified fractions of BS. • Separated fractions of the BS are more efficient against bacteria than the crude BS.

Current status and topical issues on the use of eDNA-based targeted detection of rare animal species.

Animal detection through DNA present in environmental samples (eDNA) is a valuable tool for detecting rare species, that are difficult to observe and monitor. eDNA-based tools are underpinned by molecular evolutionary principles, key to devising tools to efficiently single out a targeted species from an environmental sample. Here, we present a comprehensive review of the use of eDNA-based methods for the detection of targeted animal species, such as rare, endangered, or invasive species, through the analysis of 549 publications (2008-2022). Aquatic ecosystems have been the most surveyed, in particular, freshwaters (74 %), and to a less extent marine (14 %) and terrestrial systems (10 %). Vertebrates, in particular, fish (38 %), and endangered species, have been the focus of most of these studies, and Cytb and COI are the most employed markers. Among invertebrates, assays have been mainly designed for Mollusca and Crustacea species (21 %), in particular, to target invasive species, and COI the most employed marker. Targeted molecular approaches, in particular qPCR, have been the most adopted (75 %), while eDNA metabarcoding has been rarely used to target single or few species (approx. 6 %). However, less attention has been given in these studies to the effects of environmental factors on the amount of shed DNA, the differential amount of shed DNA among species, or the sensitivity of the markers developed, which may impact the design of the assays, particularly to warrant the required detection level and avoid false negatives and positives. The accuracy of the assays will also depend on the availability of genetic data and vouchered tissue or DNA samples from closely related species to assess both marker and primers' specificity. In addition, eDNA-based assays developed for a particular species may have to be refined for use in a new geographic area taking into account site-specific populations, as well as any intraspecific variation.

Evaluation of biotechnological processing through solid-state fermentation of oilseed cakes on extracts bioactive potential.

Oilseed cakes (OC) are natural sources of lignocellulosic biomass, produced every year in large amounts. In addition to their main applications as animal feed, plant or soil fertilizer, and compost, they present enormous potential for being used in biotechnological processes for the obtainment and extraction of valuable bioactive compounds. This work evaluated the effect of solid-state fermentation on the bioactive properties of extracts obtained from the bioprocessing of OC and evaluated the effect of solvents on the recovery of compounds with higher bioactive potential. A general decrease of EC50 values was observed for fermented extracts obtained using a mixture of water/methanol (1:1) as extraction solvent. A decrease in the minimum inhibitory concentration was observed for fermented water extracts compared to non-fermented. Additionally, growth inhibition of Listeria monocytogenes was observed when using aqueous methanolic fermented extracts. These extracts also exhibited a higher percentage of growth reduction against phytopathogenic fungi, and some extracts exhibited increased protection against genotoxic agents such as camptothecin and bisphenol A. It was demonstrated that bioprocessing of OC through SSF is an effective approach to obtaining valuable compounds with bioactive properties for use in the food, pharmaceutical or cosmetic industries.

Antibacterial and antioxidant activities of Streptomyces sp. strain FR7 isolated from forest soil.

Actinomycetes produce secondary metabolites with many bioactivities such as antimicrobial, which can be useful as alternatives against resistant bacterial strains. Therefore, the screening of new habitats is likely to provide new strains with high potential. In this work, the antimicrobial capacity was used to select Streptomyces sp. strains isolated from Raf Raf forest (Tunisia). From the strain displaying higher activity, FR7, an ethyl acetate extract was prepared under optimized culturing conditions (10 days at 30°C in ISP2 medium with initial pH 8), showing significant antimicrobial activity against Micrococcus luteus and Staphylococcus aureus (MIC = 5 µg ml-1), and Listeria monocytogenes and Pseudomonas aeruginosa (MIC = 20 µg ml-1). The extract displayed strong DPPH radical scavenging activity (IC50 = 1.3 µg ml-1) and protection of yeast cells from H2O2-induced oxidative stress determined by flow cytometry with dichlorofluorescein diacetate. The crude extract showed the presence of polyketides, with methylsalicylic acid as moiety, a large and diverse group of secondary metabolites with a wide range of bioactivities, including antioxidant and antibacterial. Based on 16S RNA gene sequences, strain FR7 was identified as belonging to genus Streptomyces with high resemblance to S. iakyrus. Streptomyces sp. FR7 has great potential as a source of antibacterial and antioxidant metabolites.

Brazilian Table Olives: A Source of Lactic Acid Bacteria with Antimycotoxigenic and Antifungal Activity.

Food and feed contamination by fungi, especially by toxigenic ones, is a global concern because it can pose serious health problems when the production of mycotoxins is involved. Lactic acid bacteria (LAB), well-known for fermenting foods, have been gaining attention for their antifungal and anti-mycotoxin properties. This work tested 14 LAB strains isolated from naturally fermented Brazilian table olives for growth inhibition of Aspergillus flavus, Aspergillus carbonarius, Penicillium nordicum, and Penicillium expansum. The strains Lacticaseibacillus paracasei subsp. paracasei CCMA 1764, Levilactobacillus brevis CCMA 1762, and Lactiplantibacillus pentosus CCMA 1768 showed the strongest antifungal activity, being more active against P. expansum. Aflatoxin B1 (AFB1), ochratoxin A (OTA), and patulin (PAT) production was reduced essentially by mycelia growth inhibition. The main organic acids detected in the cell free supernatant (CFS) were lactic and acetic acids. Tested LAB exhibited adsorption capacity against AFB1 (48-51%), OTA (28-33%), and PAT (23-24%). AFB1 was converted into aflatoxin B2a (AFB2a) by lactic and acetic acids produced by the strain CCMA 1764. A similar conversion was observed in solutions of these organic acids (0.1 M). These findings demonstrate the potential of isolated LAB strains as natural agents to control toxigenic fungi and their mycotoxins in fermented products, such as table olives.

Revealing the microbial diversity and physicochemical characteristics of Brazilian untreated green table olives.

AIM: This work evaluated the microbial diversity and physicochemical characteristics of fresh and fermented fruits from Brazilian untreated green table olives of the Ascolano and Grappolo cultivars. METHODS AND RESULTS: Twenty species of mesophilic bacteria, seven lactic acid bacteria, and fourteen yeast were identified. Some species prevailed over others, such as the bacteria Levilactobacillus brevis, Lacticaseibacillus paracasei subsp. paracasei, Pantoea agglomerans, Staphylococcus warneri, Bacillus simplex, B. thuringiensis, and the yeasts Candida parapsilosis, Ca. orthopsilosis, and Cryptococcus flavescen. In the olive fruit and olive brine, the sugars: sucrose, glucose, mannitol, and fructose, and the acids: acetic, citric, lactic, malic, and succinic were identified. Thirty-seven volatile compounds belonging to different chemical classes of acids, alcohols, aldehydes, esters, hydrocarbons, phenols, ketones, and ether were identified in the fruits and brine olives. CONCLUSION: The polyphasic methodology using matrix assisted laser desorption/ionization-time of flight and 16S rRNA sequencing was efficiently performed to identify microorganisms; chemical analysis helped to understand the fermentation process of olives.

Preservative of Essential Oil Blends: Control of Clostridium perfringens Type a in Mortadella

Abstract The aim of this study was to evaluate the antimicrobial effect of the essential oils of cinnamon, cardamom, clove, oregano, and thyme and their synergism on vegetative cells and endospores of Clostridium perfringens type A inoculated in meat sausage (mortadella), as well as the influence of blends on the color, and lipid oxidation through the determination of thiobarbituric acid reactive substances (TBARS index). The anticlostridial action of the oil blends was established. The two added oil blends (Treat. 1: oregano, clove, and thyme; Treat. 2: oregano, clove, and cinnamon) in combination with reduced nitrite content (75 ppm) promoted a lower growth of C. perfringens in mortadella stored at 15 °C for 21 days in comparison to treatments containing only 75 ppm of nitrite. The essential oil blends showed antioxidant action and did not alter food color, thus possessing potential application as a preservative for the meat products industry.

Eco-friendly biosurfactant from Wickerhamomyces anomalus CCMA 0358 as larvicidal and antimicrobial.

Kitchen waste oil (KWO) was evaluated as a substrate for production of biosurfactant by Wickerhamomyces anomalus CCMA 0358 and was tested against Aedes aegypti larvae, the mosquito causing neglected diseases, such as dengue fever, Zika, and Chikungunya, achieving 100 % mortality in the lowest concentration (6.25 %) evaluated in 24 h. Furthermore, possible applications of this compound were evaluated as antibacterial, antiadhesive, and antifungal. At a concentration of 50 %, the biosurfactant was found to inhibit the growth of Bacillus cereus, showing high inhibitions levels against Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli. The antifungal activity was evaluated against Aspergillus, Cercospora, Colletotrichum, and Fusarium, obtaining results of up to 95 % inhibition. In addition to these promising results, the yeast W. anomalus produced the biosurfactant from an inexpensive substrate, which increases the possibility of its application in several industries owing to the low cost involved.