Among 30 fungal isolates screened for lipid production using Nile-red staining assay, an isolate designated DGB1 was recorded as the highest lipid producer with lipid content up to 40% (w/w). Based on morphological, biochemical and molecular analysis, DGB1 was identified as fungal sp. strain DGB1. Under the optimized time course, lipid content of DGB1 reached its maximum yield (7.2 g/L) after four days of incubation. Gas chromatography/mass spectrometry (GC/MS) analysis revealed presence of five long chain saturated fatty acids, decanoic, tridecanoic, pentadecanoic, hexadecanoic and heptadecanoic. About 50% of these fatty acids was heptadecanoic acid. However, as a maximum, ~ 20% (w/w) of the lipid contents were determined when the basal medium containing 30% glycerol was used for lipid production instead of 5% glucose. This may push us to conclude that glucose is the most suitable carbon source which could be used to produce lipids from strain DGB1. In conclusion, this work revealed the possibility of using the promising fungal strain DGB1 in biodiesel production. Key words: Biodiesel, lipids, Geotrichum, heptadecanoic

Bacterial polymeric silk is produced by Bacillus sp. strain NE and is composed of two proteins, called fibroin and sericin, with several biomedical and biotechnological applications. In the current study and for the first time, the whole bacterial silk proteins were found capable of exerting antiviral effects against herpes simplex virus type-1 (HSV-1), adenovirus type 7 (AD7), and hepatitis C virus (HCV). The direct interaction between bacterial silk-like proteins and both HSV-1 and AD7 showed potent inhibitory activity against viral entry with IC₅₀ values determined to be 4.1 and 46.4 μg/mL of protein, respectively. The adsorption inhibitory activity of the bacterial silk proteins showed a blocking activity against HSV-1 and AD7 with IC₅₀ values determined to be 12.5 and 222.4 ± 1.0 μg/mL, respectively. However, the bacterial silk proteins exhibited an inhibitory effect on HSV-1 and AD7 replication inside infected cells with IC₅₀ values of 9.8 and 109.3 μg/mL, respectively. All these results were confirmed by the ability of the bacterial silk proteins to inhibit viral polymerases of HSV-1 and AD7 with IC₅₀ values of 164.1 and 11.8 μg/mL, respectively. Similarly, the inhibitory effect on HCV replication in peripheral blood monocytes (PBMCs) was determined to be 66.2% at concentrations of 100 μg/mL of the bacterial silk proteins. This antiviral activity against HCV was confirmed by the ability of the bacterial silk proteins to reduce the ROS generation inside the infected cells to be 50.6% instead of 87.9% inside untreated cells. The unique characteristics of the bacterial silk proteins such as production in large quantities via large-scale biofermenters, low costs of production, and sustainability of bacterial source offer insight into its use as a promising agent in fighting viral infection and combating viral outbreaks.