Annual Research & Review in Biology

This particular work deals with the Pucciniales fungi (Basidiomycetes) of Morocco. Surveys in northern Atlantic Morocco have allowed collecting dozen species of plants (Oxalis corniculata, Vicia sativa and Lotus edulis) infected by rust. The different symptoms that have been observed are described in the laboratory and a microscopic study of spores, allowed to identify the responsible pathogens for these symptoms which are like: Puccinia oxalidis, Uromyces ervi and Uromyces genistae-tincortoriae. The obtained results help to know the diversification of host Pucciniales and the description of other new species for that cause the fungal diversity of Morocco is to be known.

Aims: Design and assembly of an inexpensive microfluidic PDMS chip for visual detection of cell adhesion and biofilm formation.

Study Design: Three different styles of microchannels (2.6, 5.0, and 11.5 µl volumes) were designed, fabricated and tested for adhesion and biofilm formation in a microfluidic system. The pressure drop measurements system includes a bio-Ferrograph connected to the PDMS microchannel via a syringe and a pressure transducer.

Methodology: Microfluidic chips were fabricated using Polydimethylsiloxane (PDMS) by means of soft lithography. Different cell densities of E.coli K12 cells were introduced to investigate adhesion and biofilm formation at different time intervals. Stabilization time and hydraulic resistance were obtained via a Bio-Ferrograph connected to a pressure transducer.

Results: PDMS microfluidic volume (2.6 µl) failed to generate noticeable biofilm, while slight and greatest yield occurred with PDMS microchannels (5.0, and 11.5 µl), respectively, and could detect as low as 26 cells in 11.5 µl microchannel. As incubation time and/or initial cell density increases, cell adhesion increased, illustrated by crystal violet color intensity. High stabilization time (3 h) didn’t allow for bacterial attachment and cultivation inside the microchannel (2.6 µl) while lower stabilization time (10 min) yielded the highest capacity of cell adhesion in microchannel (11.5 µl). 

Conclusions: We developed a microfluidic chip with low stabilization time and hydraulic resistance, thus offering more volume for adhesion of bacterial cells and biofilm formation. It allowed bacterial cultivation without any addition of nutrients. The microfluidic chip provides a platform to monitor biofilm growth and can be integrated in situ investigations for biological systems, food biotechnology and other industrial biotechnology applications. This would allow a non-destructive and non-invasive monitoring of the biofilm-forming bacteria inside the PDMS microfluidic chip. This work opens opportunities for further investigations of pressure drop phenomena in microchannels that would otherwise go unnoticed in macro scale measurements.

Ocimum basilicum L. (‘licorice’ variety) is a plant commonly known as albahaca or basil that is used in a variety of industries around the world. The variability in the chemical composition of the essential oil derived from this plant, gathered in different growing months, is reported herein. The aerial parts, those parts exposed to the air, of O. basilicum L. yielded an average of 0.3% ± 0.25% of the essential oil in the four month period of the evaluation.

Using GC-MS analysis, 107 components were detected in the essential oil, 102 of them were identified (95.3%) and 15 showed a greater than 1% relative yield. Estragol, at 40.6%, and linalool, at 17.8%, were the most important components of the essential oil.

According to the refractive index (1.5230), the essential oil could be classified into the Reunion Type. Based on the relative percentage of the two most important components, estragol and linalool, the essential oil could be classified as European Type 1, and considering the possible chemo type based on the percentage of estragol, the classification corresponded to the BA Type.

This is the first time that an evaluation of the changing chemical composition of the essential oil derived from O. basilicum over four consecutive months has been published.

This investigation aimed to focus on how cobalt can avoid the damage caused by salinity stress (NaCl) on Pineapple cv. Queen in vitro. Multiplicated pineapple explants (10 – 12 mm) were subjected for eight weeks to different NaCl conc. (0, 65, 135 or 200 mM) half of them were treated firstly with 5 mg/L Cobalt sulphate. Vegetative growth parameters (no.of shoots, no. of leaves, and shoot length/explant), mineral composition (N, P, K, Na, Cl, Fe, Mn, Zn, Cu and cobalt), proline and protein content were determined. Molecular characterization using PCR based RAPD was carried out to describe the genetic differences resulted from the studied treatments, (salinity and salinity combined with cobalt sulfate). Results show that, pineapple explants growth under salt stress wasn’t prohibited completely specially below 135 mM of NaCl, but it affected negatively with the highest salt stress 200 mM of NaCl. Explants treated with cobalt before subjected to salinity scored the highest significant percentage of vegetative growth characteristics compared with those untreated. Explants treated firstly with cobalt resulted in a significantly decrease of Na⁺ and Cl^-. Cobalt has a positive effect on Macro and Micronutrients, proline and protein content. A total of 34 DNA fragments varying from 186-1456 (bp) were amplified, of which 16 were polymorphic and seven observed as a unique markers that revealed 64.03% polymorphism.

Two oleaginous yeast strains identified as Issatchenkia orientalis D5 and Candida tropicalis S5 were evaluated for oil production under optimized growth factors. Both strains were inoculated in 2L of optimal fermentation broth medium for 9 days. Sample was taken periodically (24 hrs.), The data exhibited that cell biomass was gradually increased along with time sample to reach maximum values of cell dry weight (11.22 & 13.30 gL^-1) after 8 and 9 day at consumed sugar equal to 79.52 and 156.29 gL^-1 for Candida  and Issatchenkia. It was found that Candida gave the highest values of lipid weight, lipid content, lipid yield, conversion coefficient and lipid productivity after 6 days being 2.16 gL^-1, 34.17%, 2.70%, 2.73% and 0.36 gL^-1/day, while Issatchenkia recorded the highest lipid concentration and lipid yield after 4 days of the fermentation period being 3.24 gL^-1 and 2.06%. The specific growth rate, doubling time, multiplication rate and number of generation were 0.317 day^-1, 2.18 days, 0.458 day^-1 and 1.37 for Candida and reached to 0.275 day^-1, 2.52 days, 0.396 day^-1 and  0.793 for Issatchenkia. The data proved that the strains Issatchenkia orientals and Candida tropicalis could be used as feedstock producers for microbial lipid production.