Screening of microorganisms for hydrolyases with commercial potential

Advancement in green chemistry has increased the use of microbial hydrolyases in various industries and chemical processes because of high catalytic efficiency, specificity, cost-effectiveness and eco-friendly nature. Bioconversion of tannins such as tannic acid is achieved by tannin acyl hydrolase, also known as tannase. It converts tannic acid into glucose and gallic acid by catalyzing the hydrolysis of ester and depside linkages in tannic acid. Tyrosinase is monophenol and O-diphenol oxidase a copper containing enzyme catalyzes the oxidation of tyrosine and generates different types of pigment such as melanin. Xylanases hydrolyze xylan into its constituent sugar with the help of several debranching enzymes. Microbial strains isolated from various sources were screened for these hydrolyases: Bhavnagar marine salterns (Bacillus megaterium BVUC_01 and Bacillus licheniformis BVUCh_02); Okhamadhi marine salterns Aspergillus versicolor; Spoiled/infected pomegranate (Xenoacremonium falcatum, two strains PGF1 and PGF4, Bacillus velezensisPGF2 and Candida freyschussiiPGF3. The other laboratory maintained bacterial cultures namely, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi were also used in this study. Asp. versicolor and Xen. falcatum (PGF1) produced all the three enzymes (tannase, tyrosinase and xylanase). B. licheniformis, B. megaterium, B. subtilis, B. velezensis produced tyrosinase and xylanase. Xen. falcatum (PGF4) and PGF2 produced tannase and xylanase. PGF3 produced tannase and tyrosinase. While, Bacillus megaterium and Salmonella typhi showed only tyrosinase activity. Candida freyschussii showed tannase activity. Staphylococcus aureus did not produce any of these enzymes.

Diversidade da microbiota de fungos da própolis in natura / Diversity of in natura propolis fungal microbiota

O presente estudo teve por objetivo realizar a identificação dos fungos encontrados na própolis produzido por Apis mellifera L. da Baía do Iguape, Brasil. Para tanto, foram utilizadas técnicas morfológicas, bioquímicas e moleculares, sendo averiguado o perfil de restrição gerado por espaçador interno transcrito (ITS1 e ITS4). O tamanho dos produtos de PCR foi analisado quanto ao perfil de restrição obtidos com endonuclease (HhaI, HaeIII e HinfI) por espécie. Foram identificadas dezesseis espécies de fungos filamentosos: Flavodon flavus, Aspergillus nomius, Aspergillus versicolor, Cladosporium sp., Coniothyrium sidae, Didymella sp., Paecilomyces variotii, Cladosporium cladosporioides, Penicillium citrinum, Fusarium incarnatum, Penicillium chermesinum, Phoma sp., Stagonosporopsis valerianellae, Phoma medicaginis, Paraphoma fimeti e Stagonosporopsis cucurbitacearum; e seis espécies de leveduras: Candida tropicalis, Candida guiliermondii, Candida famata, Kodomala ohmeri, Trichosporon asahiu e Cryptococcus laurentii. Stagonosporopsis cucurbitacearum e leveduras pertencentes ao gênero Candida foram os microrganismos de maior ocorrência nas amostras da própolis provenientes da Baía do Iguape, Brasil.

First report of Aspergillus versicolor associated with fruit rot disease of tomato (Solanum lycopersicum) from India

Tomato (Solanum lycopersicum L.) is an important vegetable crop and cultivated throughout India. During 2019-20, Karnataka produced 2163 tonnes of tomato, accounting for 10.51 percent of total production (https://agricoop.gov.in/horticulture-reports). During a survey conducted in September 2019 in southern Karnataka region, severe fungi fruit rot symptoms were observed on at harvest in a 18 hectare production operation. The incidence of fruit rot disease was estimated around 12–14% in an area of 18 hectares (~62 fields). The necrotic lesions on infected fruit were covered with. The fruit rot was characterised by necrosis lesions filled with black fungal fruiting bodies, which later became soft and fully necrotic. A total of 20 samples were used for isolation and diagnostics. Infected fruit rot samples were surface sterilized with 2% NaOCl for 2 min, rinsed thrice in sterile distilled water, and plated on potato dextrose agar (PDA) medium amended with chloramphenicol (40mg/L). The plates were incubated at 28±2 °C and pure cultures were obtained by hyphal tip excision. On PDA medium, fungal colonies were initially white, but later turned to yellow green, often intermixed with pink sections. They produced sulcate and centrally raised sporulating conidiophores which were hyaline or slightly pigmented with smooth walls. Vesicles produced on conidiophores were sub-globose to ellipsoidal with phialides borne on metulae. Conidia were globose, brownish and conspicuously echinulate. On the basis morphological and cultural characteristics, the causative pathogen was identified to be Aspergillus versicolor (Jurjevic et al., 2012). Further molecular characterization was also done by amplifying internal transcribed spacer (ITS) region using universal ITS1-ITS4 primers with three representative isolates (White et al. 1990). Genomic DNA was isolated using CTAB using 15 days old culture followed by PCR amplification using ITS1-ITS4 primer pair and sequencing. The sequences analysis had 100% (561/561 base pairs) similarity with the reference sequences of Aspergillus versicolor (KU318417.1, MT798844.1) according to BLAST analysis in GenBank. The representative sequence of ITS-rDNA for three isolates viz., A. versicolor NCM_1, NCM_2 & NCM_3 were deposited in GenBank (Accession number: MZ520551.1 – MZ520553.1). Pathogenicity tests were conducted on 10 healthy mature fruit of tomato F1 hybrid (INDAM 3003) using wound inoculation (conidial suspension 3 × 106 conidia mL−1). Several tomato fruit (n=5) were only inoculated with sterile water to serve as controls. The experiments were conducted in triplicates with 10 fruits each and repeated three times (Mahadevakumar et al. 2019). Within 7 days of post-inoculation, fruit rot symptoms similar to those in the original out break in Karnataka were observed on all inoculated fruit. Control fruit remained asymptomatic even after 10 days. The pathogen was reisolated from diseased fruit and the identity was confirmed based on morphology and ITS sequencing. A. versicolor has been reported as a post-harvest fungal pathogen on other various vegetable crops (Aidoo, 1993). Tomato fruit rots are known to be a major problem (Nizamani et al., 2021) in the region. However, there no reports of tomato fruit rot caused by A. versicolor in India (Farr and Rossman, 2021), which warrants additional attention as a potential threat to regional production.

Literature review of fungi in buildings and their ability to methylate chlorophenols into malodorous chloroanisoles

A source of indoor malodor in older buildings are chloroanisoles, a methylation from chlorophenols. Chlorophenols were commonly used in wood preservatives 50 years ago which were used to treat construction details exposed to high moisture loads. The methylation process requires a methylator in the form of fungi or bacteria in conjunction with adequate growth conditions for said fungi. The food industry has a history of issues with chloroanisoles contaminating different food items. There have been studies made on fungi species found in the packaging materials or surfaces in proximity and their ability to methylate various chlorophenols. Different species of fungi are present in many places, not only packaging materials but also various building materials. A literature review has been made in this study to compare fungi species able to methylate chlorophenols and their potential occurrence in wooden construction details in buildings. Two species were found to be considered strong methylators and also commonly found in wooden constructions, Aspergillus versicolor and Paecilomyces variotii. The properties of these fungi will be used for future studies of the conditions achievable in wooden constructions where the historic wood preservatives were likely used.

A Kinetic model for submerged citric acid production by Aspergillus versicolor using oil palm empty fruit bunch

The fermentation kinetics of citric acid by Aspergillus versicolor was studied in a submerged batch system. The logistic equation for growth, the Luedeking–Piret equation for citric acid production and modified Luedeking–Piret-like equation for glucose consumption was proposed for this study. The model appeared to provide a reasonable description for each parameter during the growth phase. The production of citric acid was growth-associated.