Different factors affecting growth and amylase production by fungi inhabiting poultry feeds

Abstract

Extracellular amylase synthesis by Aspergillus f l a w s and A. fumigatus, isolated from poultry feeds, was studied in stationary liquid medium. Maximum mycelium and extracellular amylase were produced after 7 days of incubation at 30 "C and after 5 days at 35 "C by A.flavus and A. fumigatus, respectively. Optimal amylase yield was obtained at pH 8 and 6 by the two fungi, respectively. Amylase production did not depend on the presence of starch in the growth medium but its inclusion in the medium enhanced amylase production by A . fumigatus. Sucrose appeared to be a poor carbon source for amylase synthesis by the test fungi. Growth on varying nitrogen sources showed that glycine promoted amylase production by A.flaous while yeast extract achieved maximum enzymatic yield by A . fumigatus.Microorganisms, including fungi, are responsible for the spoilage of agricultural products during storage (MULINGE and APINIS 1969). This is particularly pronounced when storage conditions are favourable for microbial colonization of such microorganisms (OGUNDERO 1983, MOHARRAM et al. 1989.Feeds stored under conditions encourage fungi development may adversely affect health and performance of animals (BARTOV et al. 1982). BEASLEY et al. (1980) found that chicks fed corn inoculated with Penicillium lanosum developed diarrhoea and grew at a slow rate than the controls.The deleterious effect of fungi contaminated feeds could be attributed to the presence of mycotoxins or decrease in their nutritional value (BARTOV etal. 1982). The possible effect of fungi on the nutritional value of feedstuffs has not received much attention. RICHARDSON et al. (1962) observed in poults receiving moldy soybean meal a growth depression that was prevented by the addition of lysine.The raltive ease these fungi carry out the biodegradation of feeds is directly linked to their capability to produce some extracellular enzymes. The proteolytic activity of fungi isolated from poultry feeds was previously studied in this laboratory (MEGALLA et al. 1990).The present study was designed to investigate the effect of environmental and nutritional factors on the capability of fungi inhabiting poultry feeds to produce amylase necessary for the hydrolysis of starch in these feeds. Materials and methodsOrganisms and culture maintenance: The two isolates of Aspergillusflavus and A. fumigatus used in this study were isolated from poultry feedstuffs (MOHARRAM et al. 1989). Preliminary studies had shown that, these two isolates produced appreciable amounts of amylase on solid synthetic starch yeast extract medium (SYEM). Cultures were maintained on CZAPEK'S yeast extract agar.Growth medium and amylase production: The test fungi were cultured in a liquid medium with a composition in g of soluble starch (MERCK), 5.0, yeast extract 2.0, KH,PO, 1.0, MgSO, . 7 H,O 0.5, distilled water 1 litre with a pH 7.5. This medium was autoclaved (121 "C for 15 min), allowed to 13'

Amylase production by Aspergillus niger in submerged cultivation on two wastes from food industries

“…Mahmoud (1993) obtained the higher amylase production by A. flavus and A. fumigatus using glycine and yeast extract as N sources whereas Kundu, Das, and Grupta (1973) reported NH 4 NO 3 and NaNO 3 as best nitrogen sources for maximum amylase production by A. oryzae. Torrado, González, and Murado (1998) reported NaNO 3 and (NH 4 ) 2 HPO 4 as best N sources for amylase production in A. oryzae in a medium prepared with mussel processing wastes.…”

Optimization of growth and extracellular glucoamylase production by Candida famata isolate

“…Amylases have important applications in diverse industries such as baking, brewing, detergent, medicine, textile, paper and pharmaceutical (Kennedy, 1987). Extracellular amylase (Tani et al, 1986;Mahmoud, 1993) have been found in various species of fungi (Pandy et al, 2000;Jaffar et al, 1993;Norouzian and Jaffar, 1993;Frandsen et al, 1999;Reilly, 1999), bacteria (Srivastava and Baruah, 1986;Tanaka et al, 1987) and yeasts (Bui et al, 1996;Yamashita et al, 1987;Yamashita et al, 1985;Dohmen et al, 1990;Hostinova et al, 1991).…”

Factors responsible for production of amylases from Aspergillus fumigatus Fresenius

“…The results are in agreement with the findings of other investigators who observed maximum enzyme activity, protein and biomass formations at pH 6.0 by Aspergillus spp. (Abu et al 2005, Abu-Zeid 1997, Fabiana et al 1999, Okolo et al1995 and other fungi (Mahmoud 1993) and bacteria (Freer 1993).…”

“…Since starch is the only natural substrate to be hydrolyzed by amylases, it is desirable to recover potential microbial isolates producing high level of amylase active on raw starch (Pandey et al 2000). Fungal amylase activity is influenced to a great extent by pH (Abu-Zeid 1997, Filipov et al 1982, Kachelkina and Oreshchenko 1980, Okolo et al 1995, Olasupo et al 1996, Rahman et al1993, temperature (Abu-Zeid 1997, Okolo et al 1995, Olasupo et al 1996, Srivastava and Baruah 1986, incubation period (Bormiss et al 1981, Marzan et al 2001, Rahman et al1993, various carbon and nitrogen sources (Guo et al 1988, Lachmund and Ruttkowski 1990,Mahmoud 1993, Okolo et al 1995 and also substrate concentration. Considering the above, the present work has been under taken to investigate the influence of some factors on the production and activity of amylases from the fungal isolate Aspergillus fumigatus.…”