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Microbial L-asparaginase (ASNase) is an important anticancer agent that is used extensively worldwide. In this study, 40 bacterial isolates were obtained from the Red Sea of Saudi Arabia and screened for ASNase production using a qualitative rapid plate assay, 28 of which were producing large L-asparagine hydrolysis zones. The ASNase production of the immobilized bacterial cells was more favorable than that of freely suspended cells. A promising isolate, KKU-KH14, was identified by 16S rRNA gene sequencing as Bacillus licheniformis . Maximal ASNase production was achieved using an incubation period of 72 h, with an optimum of pH 6.5, an incubation temperature of 37 °C, an agitation rate 250 rpm, and with glucose and (NH 4 ) 2 SO 4 used as the carbon and nitrogen sources, respectively. The glutaminase activity was not detected in the ASNase preparations. The purified ASNase showed a final specific activity of 36.08 U/mg, and the molecular weight was found to be 37 kDa by SDS-PAGE analysis. The maximum activity and stability of the purified enzyme occurred at pH values of 7.5 and 8.5, respectively, with maximum activity at 37 °C and complete thermal stability at 70 °C for 1 h. The K m and V max values of the purified enzyme were 0.049995 M and of 45.45 μmol/ml/min, respectively. The anticancer activity of the purified ASNase showed significant toxic activity toward HepG-2 cells (IC 50 11.66 µg/mL), which was greater than that observed against MCF-7 (IC 50 14.55 µg/mL) and HCT-116 cells (IC 50 17.02 µg/mL). The results demonstrated that the Red Sea is a promising biological reservoir, as shown by the isolation of B. licheniformis , which produces a glutaminase free ASNase and may be a potential candidate for further pharmaceutical use as an anticancer drug.

Physically crosslinked poly(vinyl alcohol)-hyaluronic acid (PVA-HA) hydrogel membranes composed of different amounts of HA were prepared by freeze-thawing (F-T) method. F-T cycle was repeated for three consecutive cycles. HA was chosen and routinely utilized in the local treatment of chronic wounds, because of its advantages as, HA is endogenous and biodegradable polymer. Physicochemical properties of PVA-HA membranes such as, gel fraction (GF), swelling, mechanical properties, hydrolytic degradation and in vitro bio-evaluation tests were investigated. Results revealed that introducing HA into PVA structure affected significantly the physicochemical properties of membranes than the pristine PVA, because of its crosslinking interaction with PVA. With the increase of HA content in PVA hydrogel membranes, GF and mechanical stability of PVA-HA membranes decreased. However, the swelling behavior, mechanical flexibility, protein adsorption and hydrolytic degradation of PVA membrane increased. The HA content < 20% in PVA hydrogels showed high cell viability (%) and no toxicity was observed using microculture tetrazolium assay (MTT-assay). However, less cell viability was determined with high HA incorporation. PVA-HA-ampicillin free showed antimicrobial activity against Candida albicans as a result of HA presence. Thus, ampicillin-loaded wound dressing with PVA-HA membranes could be used as promising materials with easy forming and biologically evaluated for wound care. ]]>

Bacterial cellulose (BC), a promising polysaccharide of microbial origin, is usually produced through synthetic (chemically defined) or natural media comprising of various environmental wastes (with exact composition unknown), through low-cost and readily available means. Various agricultural, industrial, and food processing wastes have been explored for sustainable BC production. Both conventional (using one variable at a time) and statistical approaches have been used for BC optimization, either during the static fermentation to obtain BC membranes (pellicle) or agitated fermentation that yields suspended fibers (pellets). Multiple studies have addressed BC production, however, the strategies applied in utilizing various wastes for BC production have not been fully covered. The present study reviews the nutritional requirements for maximal BC production including different optimization strategies for the cultivation conditions. Furthermore, commonly-used applications of BC, in various fields, including recent developments, and our current understanding have also been summarized.

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