Apiin-induction of β-apiosidase production by Aspergillus sp. strains

Abstractβ-Apiosidase is a rare glycosidase applied in winemaking for flavour enhancement. This enzyme is involved in the release of volatile terpenes by hydrolysis of their odourless glycosidic precursors. It is found as a minor component in commercial pectinase/cellulase preparations. Microbial production of β-apiosidase by two Aspergillus sp. strains was investigated. Apiin-induced production of this extracellular glycosidase was confirmed only during the cultivation of Aspergillus niger CBS 554.65 but the high productivity value reported in the work of Dupin et al. (1992) J. Agric. Food Chem. 40(10): 1886—1891 could not be reproduced. The achieved productivity was by far not satisfactory considering the apiin cost. Commercial enzyme preparations with β-apiosidase side-activity thus remain a better alternative as the enzyme source for biocatalytic applications.

Analysis of the transport of imported food in Spain and its contribution to global warming

Through the process of globalization, food has experienced an intense territorial restructuring process. Local agric-food links have weakened at the same time as daily products arrived from distant lands. There is presently a wide international debate on the importance of transport in the configuration of the agric-food system and its contribution in terms of greenhouse gas (GHG). The direct environmental costs of the transport of imported food, that is the ‘external food miles’, have been estimated in kilometer (km), ton (t), ton-kilometer (t-km) and GHG in Spain between 1995 and 2011. The analysis is made by ten food groups including 136 products, with special attention to the most important ones (cereals and animal feed), as well as by means of transport (air, rail, road and water) and from 113 different countries belonging to six geographical areas. Two phases are identified during this period: an expansive phase (1995–2007), in which the t-km of imported food increased from 81.8 to 147.8 million t-km and environmental pressure rose from 3.1 to 5.4 million CO2-eq t, and a recession phase (2007–2011), in which environmental pressure subsided as a consequence of the reduction of imports, even though it still remained above the 1995 level. The article reveals a clear interrelation between amounts, distances and modal distribution when it comes to determining the environmental cost of transporting food imports in the two periods studied. It also reflects on the role of the external food miles in the Spanish agri-food system from a sustainability perspective.

First Report of Potato Stem Canker Caused by Rhizoctonia solani AG-5 in China

Potato (Solanum tuberosum L.) is grown worldwide as a major food crop. Potato stem canker is an important disease mainly caused by Rhizoctonia solani AG-3 (4). In 2011, samples of potato stem canker were collected from 26 sites in Heilongjiang Province, northeast China. Stem fragments taken from the margins of the healthy and diseased tissues were surface disinfected with 0.5% NaOCl for 2 min, rinsed with sterile water, then placed on potato dextrose agar (PDA) at 25°C in the dark. Twenty-two fungal isolates taken from single hyphal tips were identified as R. solani based on morphological traits. Colonies were light brown with abundant growth of mycelia and produced brown, irregular sclerotia after 20 days on PDA. Mycelium was branched at right angles with a septum near the branch and a slight constriction at the branch base. Hyphal cells were determined to be multinucleate (five to 13 nuclei per cell) when stained with 4′-6-diamidino-2-phenylindole (DAPI). Anastomosis groups were determined by pairing with reference strains (kindly provided by N. Kondo, Hokkaido University, Japan) (1), and six out of 22 isolates anastomosed with R. solani AG-5. The internal transcribed spacer (ITS) region of rDNA was amplified from genomic DNA of the AG-5 isolates with primers ITS1 and ITS4. The ITS sequences (GenBank Accession Nos. JQ946291 to JQ946296) were 99% identical to R. solani isolate AG-5 ND1 (GenBank Accession No. HQ629863). Therefore, based on molecular characteristics and the anastomosis assay, these six isolates were confirmed to be R. solani AG-5. To determine the pathogenicity of R. solani AG-5 isolates, potato seed tubers (cv. Favorita) with 3- to 5-mm sprouts were inoculated with wheat seeds (sterilized by autoclaving twice at 121°C for 1 h with a 24-h interval) colonized with each isolate (2). Wheat seeds were placed 10 mm above the uppermost sprout tip (one seed per sprout). Plants were incubated in glasshouse conditions maintained at 25 to 27°C. After 3 weeks, all inoculated plants showed symptoms of potato stem canker disease, whereas control plants inoculated with sterilized wheat seeds remained healthy. R. solani AG-5 was consistently reisolated from symptomatic stems, and the identity was confirmed by morphological and molecular characteristics as previously described, fulfilling Koch's postulates. Potato stem canker caused by R. solani AG-5 was previously detected in Australia, South Africa, Finland, and Japan (3). However, to our knowledge, this is the first report of R. solani AG-5 on potato in China. Besides previously reported AGs 1, 3, and 4 implicated in Rhizoctonia disease in China, AG 5 should also be taken into account when designing programs for disease management in potato. References: (1) W. C. Kronland and M. E. Stanghellini. Phytopathology 78:820, 1988. (2) M. J. Lehtonen et al. Plant Pathol. 57:141, 2008. (3) M. J. Lehtonen et al. J. Agric. Food Sci. 18:223, 2009. (4) L. Tsror. J. Phytopathol. 158:649, 2010.

Lihaluujauho ohran ja kauran lannoitteena

Väkilannoitteiden tuottaminen perustuu fossiilisen energian käyttöön. Erityisesti väkilannoitteiden sisältämän typen valmistamien vaatii runsaasti uusiutumatonta energiaa. Toisaalta väkilannoitteissa hyödynnetään myös erittäin rajallisia mineraalisia esiintymiä, kuten apatiittia fosforin lähteenä. Väkilannoitteiden käyttöä ei voida pitää kestävän kehityksen tavoitteiden mukaisena. Väkilannoitteita täydentäviä tai niitä korvaavia orgaanisia lannoitteita on kehitetty viime vuosina. Orgaaniset lannoitteet perustuvat teollisessa tuotannossa ja yhdyskuntien toiminnoissa syntyvien jäteaineiden tai sivutuotteiden hyödyntämiseen. Kiinnostus orgaanisiin lannoitteisiin on viime vuosina ollut suurta, myös siksi että niiden avulla voidaan parantaa ruokajärjestelmän ravinnekiertoa. Markkinoille on esimerkiksi tullut jätevedenpuhdistamojen kehittämiä lannoitteita. Orgaanisten lannoitetuotteiden tarve korostuu luonnonmukaista kasvinviljelyä harjoittavilla tiloilla. Koska luomuviljelyssä ei sallita väkilannoitteita, on erityisesti karjattomilla tiloilla tarvetta saada käyttökelpoisia eloperäisiä lannoitteita, jotka korvaavat satojen mukana poistuneita ravinteita. Lihaluujauho, jota muodostuu teurastamoteollisuuden eläinperäisten sivutuotteiden käsittelyn yhteydessä, sisältää merkittäviä määriä kasvinravinteita. Keskimääräiset arvot ovat 8 % N, 5 % P, 1 % K ja yli 10 % Ca; näiden määrien perusteella lihaluujauho voisi hyvin toimia lannoitteena. Lihaluujauhoa valmistetaan Suomessa noin 25 000 tonnia vuodessa. EU-maissa lihaluujauhon käyttö orgaanisena lannoitteena sallittiin EY asetuksella No 181/2006. MTT:n Etelä-Pohjanmaan tutkimusasemalla Ylistarossa toteutetuissa kokeissa vuosina 2000–2003 lihaluujauhoa verrattiin tavalliseen väkilannoitteeseen tutkimuslohkolla, jossa käytettiin tavanomaisen viljelyn menetelmiä. Lannoitteen testaamiseksi tehtiin kaksi täydellisten kerranteiden osaruutukoetta: kaksivuotinen lannoituskoe ohralla ja kolmivuotinen lannoituskoe kauralla. Kaurakoetta jatkettiin neljäntenä vuonna jälkivaikutuskokeena. Koetekijät olivat lannoitelaji ja typen määrä portaina. Väkilannoitteena, johon lihaluujauhoa verrattiin, käytettiin seoslannoitetta (20 % N, 3 % P, ja 9 % K). Typpiportaat olivat 60, 90 ja 120 kg N ha-1. Lihaluujauholannoituksen satomäärä ei eronnut merkitsevästi väkilannoitteella saadusta millään typpilannoituksen tasolla. Kokonaissato nousi 120 kilon typpitasolla ohralla 4500 kiloon ja kauralla 5000 kiloon hehtaarilta, mitkä vastaavat samankaltaisissa viljelyolosuhteissa Suomessa saatavia keskimääräisiä satoja. Lisäksi osoittautui, että lihaluujauho- ja väkilannoituksella ei ollut merkitsevää eroa viljan laatutekijöiden kannalta. Kokeessa määritellyt laatuominaisuudet olivat 1000 siemenen paino, hehtolitrapaino, valkuaispitoisuus ja valkuaissato. Koska lihaluujauhon N/P – suhde on pieni, fosforia kertyy maahan, kun lihaluujauhoa käytetään typpilannoitteena. Lihaluujauholannoituksen käyttömäärät tulee sovittaa tilan viljelykiertoon niin, että samalla voidaan saavuttaa myös ympäristönsuojelun tavoitteet. Työ on julkaistu vertaisarvioituna (Chen et al. 2011. Agric. Food Sci 20: 235–244).

Immunochemical Characterization of Temperature-Regulated Production of Enterocin L50 (EntL50A and EntL50B), Enterocin P, and Enterocin Q by Enterococcus faecium L50

ABSTRACT Polyclonal antibodies with specificity for enterocin L50A (EntL50A), enterocin L50B (EntL50B), and enterocin Q (EntQ) produced by Enterococcus faecium L50 have been generated by immunization of rabbits with chemically synthesized peptides derived from the C terminus of EntL50A (LR1) and EntL50B (LR2) and from the complete enterocin Q (EntQ) conjugated to the carrier protein keyhole limpet hemocyanin (KLH). The sensitivity and specificity of these antibodies were evaluated by a noncompetitive indirect enzyme-linked immunosorbent assay (NCI-ELISA) and a competitive indirect ELISA (CI-ELISA). The NCI-ELISA was valuable for detecting anti-EntL50A-, anti-EntL50B-, and anti-EntQ-specific antibodies in the sera of the LR1-KLH-, LR2-KLH-, and EntQ-KLH-immunized animals, respectively. Moreover, these antibodies and those specific for enterocin P (EntP) obtained in a previous work (J. Gutiérrez, R. Criado, R. Citti, M. Martín, C. Herranz, M. F. Fernández, L. M. Cintas, and P. E. Hernández, J. Agric. Food Chem. 52:2247-2255, 2004) were used in an NCI-ELISA to detect and quantify the production of EntL50A, EntL50B, EntP, and EntQ by the multiple-bacteriocin producer E. faecium L50 grown at different temperatures (16 to 47°C). Our results show that temperature has a strong influence on bacteriocin production by this strain. EntL50A and EntL50B are synthesized at 16 to 32°C, but production becomes negligible when the growth temperature is above 37°C, whereas EntP and EntQ are synthesized at temperatures ranging from 16 to 47°C. Maximum EntL50A and EntL50B production was detected at 25°C, while EntP and EntQ are maximally produced at 37 and 47°C, respectively. The loss of plasmid pCIZ1 (50 kb) and/or pCIZ2 (7.4 kb), encoding EntL50A and EntL50B as well as EntQ, respectively, resulted in a significant increase in production and stability of the chromosomally encoded EntP.