In Vitro and Ex Situ Biodegradation of Low-Density Polyethylene by a Rhizopus sp. Strain Isolated from a Local Dumpsite in North-East Algeria

Low density polyethylene (LDPE) is the most abundant non-degradable plastic waste. Widely used in packaging material, it represents a serious threat to all ecosystems. In the present study, a Rhizopus sp. fungal strain was isolated from soil of a landfill located in north-east Algeria and cultured on potato dextrose agar. The in vitro biodegradability of pieces of the same plastic bag (0.2, 0.4, and 0.6 g) was estimated in minimal liquid medium and on minimal solid medium. Furthermore, biodegradation of plastic bag pieces was examined in seawater, tap water and soil. The isolated Rhizopus sp. strain could degrade the plastic bag waste. The highest in vitro rate occurred in the minimal liquid medium for both the 0.4-g and 0.6-g pieces (a 20% decrease in weight). In natural media, the highest weight decrease was different depending on the substrate: 5% in seawater for the 0.2-g piece, 10% in tap water for the 0.4-g piece and 8% in soil for the 0.4-g piece. This strain could also form a biofilm in Malt Extract Broth (MEB). These results revealed that the isolated Rhizopus sp. strain has considerable biodegradative ability based on different measures

Evaluation of Antifungal and anti-aflatoxin B1 efficacy of some crude extracts of Chamaerops humilis L. against Aspergillus flavus isolated from peanuts (Arachis hypogea L.)

The present study strengthens the food preservative potential of Chamaerops humilis extracts viz. hexane extract, chloroform extract, ethanol extract, chloroform extract, and methanol extract based on their antifungal, antiaflatoxin, and antioxidant efficacy. The isolation of molds from peanuts were carried out by the suspension-dilution technique and inoculation on agar medium. Antifungal determinations were conducted using the agar plate and liquid dilution methods. The effect of C. humilis L. extracts on the production of AFB1 was determined in a SMKY broth. The molds isolated were of the genera Aspergillus, Penicillium sp., Fusarium sp., and Alternaria sp. with A. flavus (BBH-6) which is identified as the highest AFB1 producer. The minimum inhibitory concentration of extracts against the toxigenic strain of A. flavus ranged between 3.00 mg/ml and 3.50 mg/ml. The extracts were found more efficacious as they inhibited the dry mycelium weight and aflatoxin production of the aflatoxigenic strain A. flavus (BBH-6) at lower concentrations. The extracts showed fungitoxic spectrum against four molds. The IC50 value of C. humilis L. ranged between 140.4 and 189.46 μg/mg, oxidation of linoleic acid was moderately inhibited by the extracts ranges between 53.54 and 69.33%, while their total phenolic content ranged between 47.80 and 115.71 μg/ml. Based on the findings of present investigation, C. humilis L. can be introduced as a proposed solution for formulating plant-based preservative food additives.Universidade de Vigo/CISUGMinistry of Higher Education and Scientific Research of Algeria (MESRS

In Vitro Removal of Electronic and Electrical Wastes by Fungi Isolated from Soil at Annaba Area in Northeast of Algeria

Electronic and electrical wastes (EEW) have increased exponentially in recent years due to technological progress. The uncontrolled incineration of these wastes causes pollution of air, soil, and water that has dangerous effects on health of human beings and other living organisms. This work isolated fungi that are capable of degrading some of these electronic wastes. In this study, fungi isolated from soil polluted by EEW were grown on potatoes dextrose agar (PDA) medium. The estimation of the biodegradation was achieved by inoculation of both rechargeable batteries and printed circuit boards on a minimum solid and liquid medium with selected fungal strains. During the process of biodegradation on solid medium, microscopic observation was done, and on liquid medium the production of keratinolytic enzymes was evaluated using a colorimetric method after incubation with keratine powder. After 30 days, the obtained results showed that Geotrichum candidum is capable of degrading battery and circuit boards with rates of 23% and 71%, respectively, while Rhizopus stolonifer reduced battery weight by 7% and printed circuit boards by 60%. Microscopic observations showed no morphological modification in Geotrichum candidum, while there was sporocyst formation in Rhizopus stolonifer. The detection of enzymatic production indicated that there is a relation between the biodegradation process of electronic wastes and keratinolytic enzymes in Geotrichum candidum

EXTRACELLULAR LIPASE PRODUCTION BY TRICHODERMA HARZIANUM ISOLATED FROM OIL CONTAMINATED SOIL

The aim of this study was to investigate the ability of the filamentous fungus Trichoderma harzianum to secrete lipolytic activity and examined the influence of carbon on lipase production. A quantitative analysis of lipase activity was performed by the titration method using olive oil as a substrate. The isolated strain was cultivated in shaking flasks containing basal media and supplemented with olive oil 1 % (v / v) as lipid source. The effect of other carbon sources added to basal medium as lauric acid ester (Tween 80) and glucose was tested to improve enzyme production. Maximum biomass was produced at a concentration of (1906 mg∙mL-1 ± 4.58) and (622.5 mg∙mL-1 ± 9.19) in mineral medium supplemented with glucose (2 %) and Tween 80 respectively. However, the lipase activity was maximal for olive oil (1.58 IU∙mL-1 min-1 ± 0.11). The result obtained in this study indicated that olive oil proved to be the best inducer and stimulated lipase production. Glucose and Tween 80 supplied as additional carbon sources have not enhanced the lipase production, whereas they only increased the biomass of T. harzianum

ISOLATION AND IDENTIFICATION OF LIPASE-PRODUCING FUNGI FROM LOCAL OLIVE OIL MANUFACTURE IN EAST OF ALGERIA

The main objective of this work was primary screening and isolation of lipase-producing microorganisms from oil-mill waste. For the screening of fungal strains with lipolytic activity, we employed a sensitive agar plate method, using a medium supplemented with CaCl2 and Tween 80. Another Tributyrin lipase activity was detected from clearing zones due to the hydrolysis of the triacylglycerols. The evolution of biomass and enzyme production has been assayed. A quantitative analysis of lipase activity was performed by the titration method using olive oil as a substrate supplemented with glucose or Tween 80. We have isolated some lipolytic strains from oil-mill effluent. Three of them were found to be excellent lipase producers that were identified as Penicillium sp, Aspergillus fumigatus and Aspergillus terreus. Lipolytic activity and biomass were enhanced in the medium supplemented by glucose. Tween 80 is also considered as a best inducer at the concentration of 1 %. In this condition, these isolates showed maximum lipase production within 24 h; achieved (3.91 IU‧mL-1 ± 0.12) for Penicillium sp