1,721,088 research outputs found
Interactions between Bacillus amyloliquefaciens AG1 and Aspergillus spp. contaminating food and feedstuffs
No full textAspergillus is a widespread fungal genus contaminating and degrading food and feeds mostly during storage. Some species can also produce carcinogenic mycotoxins harmful for human and animal health. In this study, Bacillus amyloliquefaciens AG1 (BaAG1), active against fungal pathogens was evaluated by in vitro tests against seven Aspergillus species belonging to six Aspergillus sections. After 7 days of incubation at 25°C, mycelial growth of all fungal species was reduced from 46.53% to 60.92%, compared to the controls. The inhibitory effect of BaAG1 cell-free culture filtrate was tested by turbidimetric measurements by using ScanReady P-800 that allow the automatic and continuous monitoring of the changes in the O.D. of fungal growth over time. Two culture mediums for growth curve optimization were tested, and PDB (Potato Dextrose Broth) was selected. The activity of two concentration of BaAG1 cell-free culture filtrate against three strains (Aspergillus niger SAAF 7, A. flavus SAAF 43 and A. fumigatus SAAF 47) was assessed over 7 d periods with automated measurements every 60 min. Significant differences in AUC (area under growth curve) were recorded between the treatments and the controls. Furthermore, macro and microscopic observation on the fungal colonies showed that both the concentrations of BaAG1 culture filtrates induced morphological changes, such as absence of conidiophores and conidia, presence of cleistothecia and hyphal alterations
Fungi Associated with Olive Tree (cv. ‘Nocellara del Belice’) Decay in Trapani Province (Sicily, Italy)
Full text linkRecently, in several locations in the province of Trapani (Sicily, Italy), olive growers have reported cases of decaying olive trees of cv. ‘Nocellara del Belice’, showing symptoms of defoliation, branch drying, xylem browning, and reduced production. Internal symptoms include white and brown wood rot, starting from the base of the trunk. These alterations have been observed in trees irrigated using a pipe system at the trunk with spray sprinklers. To identify the causal agents of decay, some trees were eradicated and dissected, and woody samples were processed to isolate and identify the associated fungal micro-organisms. The most common colonies were identified using morphological (macro- and microscopical observation) and molecular (PCR amplification of the rDNA-ITS region) analyses. Nine fungal taxa were identified, of which four were associated with this decay syndrome (Coriolopsis gallica, Fomitiporia mediterranea, Kirschsteiniothelia sp., and Pleurostoma richardsiae), three were considered ubiquitous and opportunistic fungi (Alternaria spp., Aspergillus amstelodami, and Trichoderma sp.), and the other two were mycelia sterilia. Artificial inoculation satisfied Koch’s postulates, confirming the pathogenicity of the aforementioned fungi, even though the infections in the fields seem to be related to the irrigation system. This hypothesis would seem to be confirmed by the progression of decay over time in the trees subjected to the irrigation system described but not reported in olive groves differently managed. It is therefore considered appropriate to conduct further and more in-depth investigations aimed at studying the correlation between the irrigation system, presence of fungal agents, and manifestation of the syndrome. A further ongoing investigation is aimed at the use of biostimulants (Agrusaver, Savory Sun, VA LLC) on symptomatic trees, with the aim of both improving the vegetative performance of the host and limiting the symptoms detected in the field
Root inoculation with beneficial soil microbes enhances indirect plant defences induced by insect feeding and egg deposition
No full textPlants can respond to insect egg deposition by emitting oviposition-induced plant volatiles (OIPVs) recruiting parasitoids. The recruitment of carnivore insects in response to egg deposition is considered an indirect defence strategy that is widespread in the plant kingdom. In recent years, there has been increasing evidence showing that microbial colonization can influence the strength of plant responses to insect herbivory, yet no information is available on how beneficial microbes modulate indirect defences induced by insect egg deposition. In this work, we evaluated the effects of inoculation with the beneficial soil fungus Trichoderma harzianum strain T22 on a tritrophic system consisting of tomato, the southern green stink bug Nezara viridula and its associated egg parasitoid Trissolcus basalis. We used Y-tube olfactometer assays to evaluate the behavioural responses of the parasitoids to OIPVs emitted by plants colonized with beneficial soil microbes. We also used gas chromatography coupled with mass spectrometry (GC-MS) to investigate whether and how root inoculation with T. harzianum T22 affects the chemical composition of induced plant volatiles. In olfactometer assays, we found that root inoculation with T. harzianum T22 enhanced the attraction of the egg parasitoid towards tomato plants induced by N. viridula feeding and oviposition activities. In particular, the egg parasitoid preferred OIPVs emitted by tomato plants previously inoculated with T. harzianum T22 over OIPVs emitted by non-inoculated plants. Furthermore, chemical analysis showed that root inoculation with T. harzianum T22 resulted in changes in the composition of OIPVs, which was consistent with the behavioural observations. Among the compounds that strongly contribute to the chemical differences between OIPVs from non-inoculated and inoculated plants, chemical analysis identified green leaf volatiles ((Z)-3-hepten-1-ol, (E,E)-2,4-hexadienal), along with terpenoids (terpinen 4-ol, alpha-tujene and delta-elemene). Taken together our results indicate that beneficial soil microbes enhance indirect plant defences induced by feeding and oviposition, broadening our understanding of plant responses to insect eggs. Our results underscore the importance of taking into account the role of microorganisms to fully comprehend the intricate interactions among plants, herbivore eggs and their associated egg parasitoids
Fungal contaminants in Sicilian livestock feeds and first studies on the enzymatic activity of Aspergillus isolates
Full text linkThe purposes of this study were 1) to determine the total fungal contamination in Sicilian raw materials and livestock, 2) to evaluate the occurrence of Aspergillus spp., Penicillium spp. and Fusarium spp., 3) to identify fungi belonging to the genus Aspergillus and 4) to determine their ability to produce cellulolytic enzymes. Fourteen feed samples were collected in a feed mill near to Palermo (Sicily, Italy). Analysis of the total mycobiota was performed on Sabourad Dextros Agar (SAB) and Potato Dextrose Agar (PDA) and total fungal counts were expressed as CFU/g. Aspergillus spp. isolates were selected on the basis of the frequency of isolation and identifed using micro and macro-morphological characteristics and ITS sequence analysis. The ability of the Aspergillus isolates to produce cellulolytic enzymes was tested qualitatively by in vitro assay at two temperature, 25 and 30 °C, and in static and shaking condition. Total fungal population ranged from 1.11x106 to 1.31x108 and from 1.11x103 to 1.58x106 CFU/g on PDA and SAB, respectively. All feed samples showed the recurrent presence of colonies belonging mostly to the ubiquitous genera Aspergillus, Fusarium and Penicillium. Eight isolates of Aspergillus spp. were obtained and identifed as A. amstelodami, A. awamori, A. flavus, A. niger, A. oryzae and A. tubingensis. Between them, A. awamori, A. niger and A. tubingensis showed the highest enzymatic activity. The presence of potential mycotoxigenic isolates of Aspergillus spp. in the analysed feeds represents a risk for animal health; moreover their ability to produce cellulolytic enzymes can seriously affect feed quality
Primi studi sull'interazione tra stato di micorrizazione e danni da incendio in una pineta siciliana
Full text linkNell’ambito di uno studio sulle simbiosi micorriziche delle conifere in ambienti siciliani, è stata avviata un’indagine preliminare sulla interazione tra danni da incendio e stato di micorrizazione in un rimboschimento artificiale di Pinus halepensis Mill. In particolare, nel bosco di Casaboli (Monreale, PA) estesamente interessato da incendi dolosi nell’estate 2017, sono state delimitate tre aree contigue di circa 700 m2, comprendenti una ventina di piante coetanee (30-40 anni) e con differente entità di danno: 1) vegetazione apparentemente sana (S); danni di media entità (M); danni ingenti (I). In ogni area, dopo aver condotto opportuni rilievi dendrometrici, sono stati individuati 5 punti per il prelievo di carote di suolo a due profondità (5-15; 20-30 cm); i campionamenti sono stati ripetuti tre volte nel biennio 2018-19 (giugno e novembre 2018, maggio 2019) e saranno completati a novembre 2019. I frammenti radicali di P. halepensis, recuperati sotto un leggero flusso d’acqua corrente, sono stati osservati allo stereo microscopio, valutando l’Indice di Micorrizazione (IM = n° totale di apici micorrizici/cm di radice) e rilevando, sul numero totale di apici micorrizici, la percentuale di quelli attivi e non (necrotici). Sebbene l’indagine sia ancora in corso, i primi risultati sembrerebbero evidenziare valori di IM maggiori nell’area S, decrescenti in funzione del livello di deperimento. Nel contempo, nel profilo di suolo compreso tra 20 e 30 cm sono stati rilevati i maggiori livelli di micorrizazione, che rimane sensibile anche nelle aree più danneggiate. Ulteriori dati acquisiti nel corso dell’attività di ricerca potranno fornire utili indicazioni per la definizione degli effetti di tale fattore di disturbo nell’ecosistema oggetto di studio
Attacks of Kalotermes flavicollis Fabricius (1793) and Associated Aspergillus Micheli ex Haller (1768) Species
Full text linkThe yellow-necked dry-wood termite Kalotermes flavicollis (Fabricius, 1793) (Blattodea: Kalotermitidae) is an important pest that infests wood in Europe. An increase in attacks by K. flavicollis has been seen in buildings and in churches in Palermo (Italy), with attacks on both structural elements and artefacts. Future climate changes are expected to lead to increasing temperatures, which will probably affect the pest status of this species, which is difficult to control. In this context, it is important to identify potential natural antagonists of K. flavicollis. During a survey of the K. flavicollis population, several dead individuals with evident fungal efflorescence were found. Therefore, a study aimed at the isolation and identification of these microorganisms was conducted. Fungal colonies isolated from mycelial structures grown on insects were identified based on morphological characteristics and DNA profiling. Three different species were identified: Aspergillus nomius, A. subramanianii, and A. tamarii. This is the first time that fungi have been recorded in association with the yellow-necked dry-wood termite and, in addition, this study reports the first association of A. subramanianii with Isoptera
First Report of Agaricus aridicola in Saudi Arabia and Ecological Notes on Agaricus bisporus
No full textAgaricus aridicola is reported for the first time from Saudi Arabia while Agaricus bisporus is a new record
for Northern region of Saudi Arabia. This study includes notes on taxonomy, ecology and distribution of
both the species. It was also reported that the habitat of A. aridicola and A. bisporus are characterized by
calcareous sandy soil, poor in organic matter, with presence of little amount of salinity
Microbiological Aspects and Enzymatic Characterization of Curvularia kusanoi L7: Ascomycete with Great Biomass Degradation Potentialities
Full text linkThe complex structure of the plant cell wall makes it difficult to use the biomass produced by biosynthesis. For this reason, the search for new strains of microorganisms capable of efficiently degrading fiber is a topic of interest. For these reasons, the present study aimed to evaluate both the microbiological and enzymatic characteristics of the fungus Curvularia kusanoi L7strain. For this, its growth in different culture media was evaluated. Wheat straw mineralization was evaluated by gas chromatography assisted by infrared spectroscopy. The production of endo- and exoglucanase, laccase, and peroxidase enzymes in submerged solid fermentation of wheat and sugarcane bagasse were characterized. The strain efficiently mineralized raw wheat straw, showing a significant decrease in signals associated with cellulose, hemicellulose, and lignin in the infrared spectra. High enzyme productions were achieved in submerged solid fermentation of both substrates, highlighting the high production of endoglucanases in sugarcane bagasse (2.87 IU/mL) and laccases in wheat (1.64 IU/mL). It is concluded that C. kusanoi L7 is an ascomycete with a versatile enzyme production that allows it to exhaustively degrade complex fibers such as raw wheat straw and sugar cane bagasse, making it a microorganism with great potential in the bioconversion of plant biomass
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