Oil palm mesocarp fiber was subjected to hydrothermal pretreatment under isothermal and non-isothermal conditions. The pretreated slurries were separated by filtration, pretreated liquids and solids were characterized. An enzymatic digestibility study was performed for both pretreated slurries and solids to understand the effect of soluble inhibitors generated during the pretreatment process. The highest glucose yield obtained from pretreated slurries was 70.1%, and gradually decreased with higher pretreatment severities. The highest glucose yield obtained in pretreated solids was 100%, after pretreatment at 210°C for 20min. In order to study the inhibitory effects of compounds generated during pretreatment with cellulase, technical grade solutions that mimic the pretreated liquid were prepared and their effect on Acremonium cellulase activity was monitored using Avicel. Xylo-oligomers and tannic acid were identified as powerful inhibitors of Acremonium cellulase, and the lowest hydrolysis rate of Avicel of 0.18g/g-glucose released/L/h was obtained from tannic acid.
The native sago starch exists as a compact crystalline structure and is not efficiently hydrolyzed by Raw Starch Degrading Enzyme (RSDE). In order to enhance its hydrolysability, the starch was treated with acid and heated below its gelatinization temperature, thus increasing the accessibility of the sago starch granule to enzymatic attack. Results showed that treatment of sago starch with acid at pH 2.0 and temperature 65oC for 2 hours greatly enhanced its conversion rate to glucose from 53.3% to 71.9%. It is clearly shown that high yield of glucose is produced during hydrolysis of acid-treated sago starch using the Raw Starch Degrading Enzyme from Acremonium sp. The difference between the acid-treated and untreated sago starch in this study could be due to the differences on the surface of the sago starch granule which may influence the accessibility and diffusion of enzyme into the starch during hydrolysis.
Psidium guajava wilt is known from South Africa, Malaysia and Taiwan. The fungus causing this disease, Myxosporium psidii, forms dry chains of conidia on surfaces of pseudoparenchymatous sporodochia, which develop in blisters on bark. Similar sporodochia are characteristic of Nalanthamala madreeya, the type species of Nalanthamala. Nalanthamala, therefore, is the appropriate anamorph genus for Myxosporium psidii, while Myxosporium is a nomen nudum (based on M. croceum). For M. psidii the combination Nalanthamala psidii is proposed. Nalanthamala psidii, the palm pathogen Gliocladium (Penicillium) vermoesenii, another undescribed anamorphic species from palm, two species of Rubrinectria and the persimmon pathogen Acremonium diospyri are monophyletic and belong to the Nectriaceae (Hypocreales) based on partial nuclear large subunit ribosomal DNA (LSU rDNA) analyses. Rubrinectria, therefore, is the teleomorph of Nalanthamala, in which the anamorphs are classified as N. vermoesenii, N. diospyri or Nalanthamala sp. Nalanthamala squamicola, the only other Nalanthamala species, has affinities with the Bionectriaceae and is excluded from this group. Rubrinectria/Nalanthamala species form dimorphic conidiophores and conidia in culture. Fusiform, cylindrical, or allantoid conidia arise in colorless liquid heads on acremonium-like conidiophores; ovoidal conidia with somewhat truncated ends arise in long, persistent, dry chains on penicillate conidiophores. No penicillate but irregularly branched conidiophores were observed in N. diospyri. Conidia of N. psidii that are held in chains are shorter than those of N. madreeya, of which no living material is available. Nalanthamala psidii and N. diospyri are pathogenic specifically to their hosts. They form pale yellow to pale orange or brownish orange colonies, respectively, and more or less white conidial masses. Most strains of Rubrinectria sp., Nalanthamala sp. and N. vermoesenii originate from palm hosts, form mostly greenish or olive-brown colonies and white-to-salmon conidial masses. They form a monophyletic clade to which Nalanthamala psidii and N. diospyri are related based on analyses of the internal transcribed spacer regions and 5.8S rDNA (ITS rDNA), LSU rDNA, and partial beta-tubulin gene. Few polymorphic sites in the ITS rDNA and beta-tubulin gene indicate that Nalanthamala psidii comprises two lineages, one of which has been detected only in South Africa.
In January 2011, branch samples were collected from langsat (Lansium domesticum Corr.), a fruit from Southeast Asia with an expanding niche market in Hawaii, exhibiting corky bark symptoms similar to that found on rambutan (Nephelium lappaceum) and litchi (Litchi chinensis) (3). The orchard, located along the Hamakua Coast of Hawaii Island, had 5- to 10-year-old trees, all with corky bark symptoms. As the trees matured, the cankers increased in size and covered the branches and racemes, often resulting in little to no fruit production. Scattered along the infected bark tissue were elongated, black ascomata present in the cracks. Ascomata were removed from the cracks using a scalpel blade, placed at the edge of a water agar petri dish and gently rolled along the agar surface to remove bark tissue and other debris. Individual ascomata were placed in 10-μl drops of 10% sodium hypochlorite on fresh water agar for 20 s, removed, and placed on potato dextrose agar petri dishes amended with 25 μg/ml streptomycin. The isolates were kept at 24°C under continuous fluorescent lighting. After 9 days, black pycnidia were present, which produced smooth, hyaline, linear to curved, filiform conidia, 4 to 6 septate (mostly 6), 31.8 to 70.1 × 2.0 to 2.8 μm. The morphological descriptions and measurements were similar to those reported for Dolabra nepheliae (3). The nucleotide sequence of the internal transcribed spacer (ITS) region including ITS1, 5.8S, and ITS2 intergenic spacers was determined for strain P11-1-1and a BLAST analysis of the sequence (GenBank Accession No. JX566449) revealed 99% similarity (586/587 bp) with the sequence of D. nepheliae strain BPI 882442 on N. lappaceum from Honduras. Based on morphology and ITS sequencing, the fungus associated with the cankers was identified as the same causal agent reported on rambutan and pulasan (N. mutabile) from Malaysia (1), and later reported on rambutan and litchi in Hawaii and Puerto Rico (3). Upon closer observations of the diseased samples, sections of corky bark contained at least two larval insects. The beetles were identified as Corticeus sp. (Coleoptera: Tenebrionidae) and Araecerus sp. (Coleoptera: Anthribidae) by the USDA-ARS Systematic Entomology Laboratory (Beltsville, MD). A corky bark disease on the trunk and larger limbs of mature langsat trees in Florida was thought to be caused by Cephalosporium sp. with larvae (Lepidoptera: Tineidae) feeding on the diseased tissue (2). It is not known the extent to which either of the beetle species is associated with L. domesticum in Hawaii or if they play a role in the bark disorder. To our knowledge, this is the first report of Dolabra nepheliae being found on langsat in Hawaii. Effective management practices should be established to avoid potential production losses or spreading the disease to alternative hosts. References: (1) C. Booth and W. P. Ting. Trans. Brit. Mycol. Soc. 47:235, 1964. (2) J. Morton. Langsat. In: Fruits of Warm Climates, p. 201-203. Julia F. Morton, Miami, FL, 1987. (3) A. Y. Rossman et al. Plant Dis. 91:1685, 2007.
The novel antifungal agent ASP2397 (Vical's compound ID VL-2397) is produced by the fungal strain MF-347833 that was isolated from Malaysian leaf litter and is identified here as an Acremonium species based on its morphology, physiological properties and 28S ribosomal DNA sequence. Because of its potential importance for producing novel antifungal agents, we determined the taxonomic and biologic properties of MF-347833. We show here that ASP2397 is a cyclic hexapeptide that chelates aluminum ion and is therefore similar to ferrichrome, a hydroxamate siderophore. However, ASP2397 differs structurally from licensed antifungal agents such as amphotericin B, triazoles and echinocandins. To understand the relationship between chemical structure and biological function, we isolated certain ASP2397 derivatives from the culture broth, and we further chemically converted the metal-free form to other derivatives.