Kojic Acid Production from Agro-Industrial By-Products Using Fungi

A total of 278 different isolates of filamentous fungi were screened using synthetic medium for respective ability to produce kojic acid. Nineteen, six, and five isolates proved to be low, moderate, and high kojic acid producers, respectively. Levels of kojic acid produced were generally increased when shaking cultivation was used rather than those obtained using static cultivation. A trial for the utilization of 15 agro-industrial wastes or by-products for kojic acid production by the five selected higher kojic acid producer isolates was made. The best by-product medium recorded was molasses for kojic acid. A. flavus numbers 7 and 24 were able to grow and produce kojic acid on only 12 out of 15 wastes or by-products media. The best medium used for kojic acid production by A. flavus number 7 was rice fragments followed by molasses, while the best medium used for kojic acid production by A. flavus number 24 was the molasses followed by orange, pea, and rice fragments. An attempt for production of kojic acid using a 1.5 L laboratory fermentor has been made. Aspergillus flavus number 7 was used and grown on molasses medium; maximum level (53.5 g/L) of kojic acid was obtained after eight days of incubation.

Novel Coprinopsis cinerea Polyesterase That Hydrolyzes Cutin and Suberin

ABSTRACT Three cutinase gene-like genes from the basidiomycete Coprinopsis cinerea (Coprinus cinereus) found with a similarity search were cloned and expressed in Trichoderma reesei under the control of an inducible cbh1 promoter. The selected transformants of all three polyesterase constructs showed activity with p-nitrophenylbutyrate, used as a model substrate. The most promising transformant of the cutinase CC1G_09668.1 gene construct was cultivated in a laboratory fermentor, with a production yield of 1.4 g liter−l purified protein. The expressed cutinase (CcCUT1) was purified to homogeneity by immobilized metal affinity chromatography exploiting a C-terminal His tag. The N terminus of the enzyme was found to be blocked. The molecular mass of the purified enzyme was determined to be around 18.8 kDa by mass spectrometry. CcCUT1 had higher activity on shorter (C2 to C10) fatty acid esters of p-nitrophenol than on longer ones, and it also exhibited lipase activity. CcCUT1 had optimal activity between pH 7 and 8 but retained activity over a wide pH range. The enzyme retained 80% of its activity after 20 h of incubation at 50°C, but residual activity decreased sharply at 60°C. Microscopic analyses and determination of released hydrolysis products showed that the enzyme was able to depolymerize apple cutin and birch outer bark suberin.

An in vitro cultured rumen inoculum improves nitrogen digestion in mulga-fed sheep

Mixed cultures of anaerobic micro-organisms were derived from feral goat rumen fluid (FGRF) using a laboratory fermentor to selectively culture microbes actively degrading mulga, and were evaluated as rumen inocula in digestion and liveweight studies with mulga-fed sheep. When placed in the rumen of sheep, FGRF enhances mulga digestion; however, limited supplies of feral goats, the labour involved in locating and mustering goats, and likely variations in the microbial composition of FGRF between animals and localities make the production of an in vitro cultured inoculum a desirable alternative to enable widespread adoption. The cultured inoculum significantly (P < 0·05) improved nitrogen digestion and retention in mulga-fed sheep by 16 and 76%, respectively. Inocula consisting of simplified mixtures of bacteria isolated from sheep, feral goats, and native marsupials did not affect mulga digestion. In the first of 2 liveweight studies, sheep inoculated with the fermentor inoculum lost significantly less weight than uninoculated sheep for the first 57 days (0·3 v. 4·6 kg); however, after 83 days the difference in the rate of liveweight loss between the fermentor inoculum group and the uninoculated sheep was not significant (53 v. 95 g/day). In the second study, liveweight loss was not significantly reduced by the fermentor inoculum. An inoculum based on FGRF, and produced in vitro using a fermentor, is potentially valuable to grazing enterprises reliant on mulga-fed sheep. However, problems in generating a consistent inoculum need to be addressed before such an inoculum can be generally considered.