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Casuarinas are very important plants for their various uses and survival in adverse sites or harsh environments. As nitrogen fixation, in symbiosis with Frankia, is an important factor for the survival of these plants under various conditions, the basis for selecting both effective and tolerant Frankia strains and Casuarina spp., are provided. Enhancement of the symbiotic relationship between Frankia and Casuarina, by mycorrhizal infection and other biofertilizing microorganisms such as Bacillus and Azospirillum, is reflected by superior plant growth. Casuarina leaf litter is also a great source for both inorganic and organic nutrients. Therefore, careful management of the top soil layer under Casuarina trees is very important. Litter decomposition ratio is affected by many physical chemical and biological factors including temperature, moisture conditions, lignin, and C-to-N and N-to-P ratios in addition to soil biota. In general, here the above relations are discussed and an alleviation model is presented for important disturbances of natural and human origin made in soil and environment, especially in the dry regions. In conclusion, we suggest how to optimize the nitrogen fixation and plant growth under the prevalent conditions.

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The uses of whey permeate for lactic acid production is a dual-purpose process by producing lactic acid and decreasing the environmental pollution problem caused by dumping the lactose-rich dairy byproduct. This study aimed to investigate lactic acid production from whey permeates using lactic acid bacterial isolates. Five isolates from cheese samples were identified as lactobacillus casei MT682513, Enterococcus camelliae MT682510, Enterococcus faecalis MT682509, Enterococcus lactis MT682511, and Wissella paramesenteroides MT682512 using 16S rRNA. Small scale batch fermentations of permeate were conducted under uncontrolled pH conditions. pH, temperature, carbon, and nitrogen sources as well as fermentation time on the conversion rate of lactose to lactic acid were monitored. It was found that Lactobacillus casei exhibited the highest percentage of lactic acid production without any supplementations. The increasing percentage was 107% using glucose (100 gl-1) and 44.2 % using yeast extract (10 gl-1) as carbon and nitrogen sources, respectively. The optimum lactic acid production was between 30°C and 37°C within a pH value of 6. The highest production of lactic acid under the optimized conditions resulted after 14h of fermentation. This work facilitates further studies of Lactobacillus casei over the optimized conditions of whey parameters on the other industrially important for lactic acid production and applications.

In vitro antibacterial potential of chloroform, absolute ethanol, methanol, ethanol (70%) and aqueous extracts of Calotropis procera and Ficus sycomorus leaves and latex were evaluated against five Gramnegative bacteria (Neisseria lactamica ATCC 23970, Salmonella typhi ATCC 19430, Shigella flexenri ATCC 12022, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922) and two Gram-positive bacteria (methicillin-resistant Staphylococcus aureus MRSA ATCC 43300, S. aureus CONS ATCC 29213). The antibacterial activities were expressed as zone of inhibition; minimum inhibitory concentrations (MIC) and also the survival curve was determined as kinetic studies. Interestingly, among all the tested extracts, aqueous and ethanol (either absolute or 70%) of C. procera and F. sycomorus leaves and latex were the best solvents for elute polar antibacterial substances and showed bacteriocidal effect against most Gram-positive and negative bacteria. Also, latex extracts were more pronounced than leaf extracts on human pathogenic bacteria. The most resistant bacterium was E. feacalis against both plant extracts. On the other hand, S. areus MRSA was the most sensitive bacteria especially with ethanol 70% extract of leaves and latex for both plants. The results of MIC for these extracts show more or less values higher than the chloramephnicol. Our conclusion confirms that, susceptibility of Gram-positive bacteria to the aqueous or ethanolic extracts of leaves for both plants was more than those of Gram-negative bacteria. The activities of 70% ethanol extracts recorded highest activity against Gram-negative bacteria than those of other extracts. The results therefore established a good support for the use of C. procera and/or F. sycomorus in traditional medicine against Grampositive and negative pathogenic bacteria.

T HE ANTIBACTERIAL potential of Ziziphus-spina christi as methanol and ethanol extracts, of bark, fruit, roots, seeds and leaves, were evaluated against seven pathogenic bacterial strains using agar well diffusion technique: The used strains were Pseudomonas aeruginosa (ATCC 278223), Enterobacter cloacae (ATCC 13047), Enterobacter aerogenes (ATCC 13084), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 13888), Enterococcus faecalis (ATCC 29212) and Methicillin-resistant Staphylococcus aureus (MRSA, ATCC 43300). The antibiotic erythromycin was used as positive control. The presence of phytochemical compounds in the extracts was determined qualitatively, the functional bioactive groups were characterized by FTIR and the presence of bioactive elements was characterized by XRF. Antibacterial activity against the used bacterial strains was assessed by determining the minimal inhibitory and bactericidal concentrations (MIC and MBC) assays. All the used Gram negative and positive bacteria were sensitive to various plant extracts. Bark extract was the most active against all strains except for Enterobacter aerogenes. Ethanol bark extract showed great activity against Enterococcus faecalis with 16.2 mm clearing zone and MIC, MBC of 15 and 20 mg ml -1 , respectively. Methanol bark extract was also effective against Klebsiella pneumoniae with a clearing zone of 16.2 mm and 20 mg ml -1 for both MIC, MBC. Leaves extracts showed high antibacterial activity against all strains except Escherichia coli. Ethanol fruit extract also exhibited high activity against Pseudomonas aeruginosa with 20 mm clearing zone and 2.5, 10 mg ml -1 for both MIC and MBC. Finally, ethanol roots showed the largest clearing zone against Enterococcus faecalis (21mm) with 10 and 15 mg ml -1 for MIC and MBC, respectively.

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