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Plant growth-promoting bacteria (PGPB) and silicon (Si) can augment salinity tolerance in plants. In this study, 25 potential PGPB were isolated from alfalfa rhizosphere and screened for their ability to synthesize indole-3-acetic acid, 1-aminocyclopropane-1-carboxylate deaminase, and solubilize tricalcium phosphate. Two promising strains were tentatively identified as Pseudomonas pseudoalcaligenes (KB-10) and P. putida (KB-25) based on phenotypic, biochemical and 16S rRNA gene phylogeny. Subsequently, a pot experiment was conducted to evaluate the effectiveness of KB-10 and KB-25 treatment, alone or in combination with Si fertilizer, in alleviating salinity stress in coriander. The results showed that treatment with PGPB strains and/or Si significantly increased relative water content, concentrations of photosynthetic pigments, peroxidase activity, total biomass, salt tolerance index, and reduced salt-induced total phenolic contents. Overall data suggested that the combined application of PGPB and Si fertilizer could be a feasible and effective approach to improve growth and salinity tolerance in coriander.

Pseudomonas pseudoalcaligenes KB-10 can enhance salinity tolerance in coriander plants. We report a draft genome sequence of P. pseudoalcaligenes KB-10, comprising a 5,241,174-bp circular chromosome containing 4,921 genes, with a GC content of 62.97%.

Halophilic bacteria are a microorganism that grows optimally in the presence of the very high concentration of sodium chloride. Halophiles are vital sources of various enzymes including hydrolases, which are very stable and catalytically highly efficient at high salt concentration and other extreme conditions such as high temperature, pH and presence of organic solvents. Several hydrolases such as amylases, proteases, and lipases have been obtained from halophilic bacteria and are commonly used for various industrial applications. We initiated a screening project to isolate and characterize the halophilic bacteria from the Red Sea, which is one of the saltiest bodies of water in the world. Water and soil samples, collected from the Red Sea coast, Jeddah, Saudi Arabia, were screened for isolation of halophilic bacteria. Ten bacterial isolates were obtained, which were characterized by biochemical tests and 16S rRNA gene sequencing. Hydrolase producing bacteria among the isolates were screened by plate assay on starch and gelatin agar plates for amylase and protease, respectively. Two bacterial isolates i.e Bacillus haynesii and Enterobacter cloacae subsp. were found to possess significant amylase and protease activity. Further characterization of both the strains is in progress.

Objectives: To explore the risk factors, the prevalence rate, and gene types of extended-spectrum beta-lactamase (ESBL)-producing bacteria as the causative agents of infection at King Abdulaziz Specialist Hospital (KAASH), Taif, Kingdom of Saudi Arabia. Methods: This was a retrospective study conducted during the period between February 2017 and January 2018. All samples obtained from the KAASH were analyzed. The MicroScan Walkaway System, bacteriological examination and double disk synergy tests were used to detect ESBL-producing bacteria. To identify ESBL genes, the polymerase chain reaction (PCR) technique was used. Results: The ESBL phenotype was detected in 351 of 1151 isolates (30.5%); Escherichia coli ( E. coli ) (62.7%) and Klebsiella pneumoniae ( K. pneumoniae ) (23.6%) were the most prevalent. The highest proportion of ESBL specimens was found in urine (62%.5), and these organisms were mainly isolated from the female medical ward (20.2%). Based on the statistical analysis, lung diseases, renal diseases, diabetes and heart diseases contributed to the spread of ESBL infections. Amikacin, imipenem, meropenem and tigecycline were found to be effective in overcoming ESBL infections; however, these antibiotics may be inappropriate for new strains of K.pneumoniae . The distribution of the blaCTX-M gene was high (87%), compared with blaTEM (74.9%) and blaSHV (29.4%). Conclusion: These data provide new epidemiological information about the prevalence of ESBL-producing organisms among patients in KAASH, Taif, Saudi Arabia. In addition, this study identified the clonal nature of isolated E.coli and K.pneumoniae .

The phenolic content of methanol and water extracts of ginger fermented by Trichoderma spp. using solid-state fermentation (SSF) was evaluated and was compared with unfermented ginger. The total phenolic content in fermented ginger increased several times. The highest phenolic content in ginger was detected after SSF by T. viride. The optimal physiological conditions for the maximum production of phenolic compounds and β-glucosidase activity of fermented ginger by T. viride were detected at day 7 incubation, pH 6·0, 30°C and 30% moisture. The SSF of ginger by T. viride greatly enhanced the antioxidant potency of phenolic compounds and was evaluated using DPPH and ABTS assays. A potent antibacterial activity of the phenolic compounds of fermented ginger was observed against all the tested human-pathogenic bacteria. Significance and impact of the study This is the first report to investigate the optimal physiological conditions of solid-state fermentation (SSF) of ginger by Trichoderma viride for enhancing its phenolic content and antioxidant capacity. In addition, the phenolic compounds of fermented ginger could be potentially used as a dietary adjunct and an antibacterial agent.

The emergence of multidrug-resistant (MDR) microbes has become one of the major threat globally. Infectious diseases are the second leading cause of death, two-third of which are caused by Gram-negative bacteria. The increasing number of multidrug resistant (MDR) microbes is quite alarming and has raised the necessity of development of new antibacterial drugs. Escherichia coli and Klebsiella have been reported among the top most resistance-developing pathogens. Ricinus communis is an important medicinal plant reported to possess antimicrobial phytochemicals such as α-pinene. The hexane treated crude ethanolic extract of R. communis was evaluated against Gram-negative bacteria E. coli and Klebsiella oxytoca. The agar well diffusion assay was used to determine the antibacterial activity. In the present study, we have shown experimentally that leaf extract of R. communis can induce the deterioration of the inner and outer cell membranes of E. coli and K. oxytoca and decrease their viability at a concentration of 50 mg/ml. Transmission electron microscopic results revealed cell membrane damage, cellular disintegration and release of cytoplasmic content, leading to cell death. To our knowledge, this is the first study of the antibacterial activity of R. communis against E. coli and K. oxytoca by Transmission electron microscopy. The ultramicroscopic observations showed that the phytochemical present in the leaf extract of R. communis could penetrate the bacterial cell, causing rupture of cell membranes and hence confirm the cytotoxic and antimicrobial property of R. communis.

The present study was designed to isolate petroleum hydrocarbon degrading bacterial strains from crude oil contaminated sites near the ARAMCO (Jazan, Saudi Arabia). The main aim was to identify a n...

Plant associated bacteria are promising alternatives to chemical fertilizers for plant growth and yield improvement in an eco-friendly manner. In this study, rice associated bacteria were isolated and assessed for mineral phosphate solubilization and indole-3-acetic acid (IAA) production activity in vitro. Six promising strains, which were tentatively identified as phylotaxon Pseudochrobactrum sp. (BRRh-1), Burkholderia sp. (BRRh-2), Burkholderia sp. (BRRh-3), Burkholderia sp. (BRRh-4), Pseudomonas aeruginosa (BRRh-5 and BRRh-6) based on their 16S rRNA gene phylogeny, exhibited significant phosphate solubilizing activity in National Botanical Research Institute phosphate growth medium, and BRRh-4 displayed the highest phosphate solubilizing activity, followed by BRRh-5. The pH of the culture broth declined, resulting in increase of growth rate of bacteria at pH 7, which might be due to organic acid secretion by the strains. In presence of L-tryptophan, five isolates synthesized IAA and the maximum IAA was produced by BRRh-2, followed by BRRh-1. Application of two most efficient phosphate solubilizing isolates BRRh-4 and BRRh-5 by root dipping (colonization) of seedling and spraying at the flowering stage significantly enhanced the growth and grain yield of rice variety BRRI dhan-29. Interestingly, application of both strains with 50% of recommended nitrogen, phosphorus and potassium fertilizers produced equivalent or higher grain yield of rice compared to the control grown with full recommended fertilizer doses, which suggests that these strains may have the potential to be used as bioinoculants for sustainable rice production.

In this work, a five level central composite design (Box–Wilson design) was employed to optimize the operating conditions for the generation of electricity in a microbial fuel cell. The following three variables were studied: temperature, initial anodic compartment pH and salt bridge component concentrations (agar and KCl). The optimal voltage yield was 17.34% greater than that observed under basal conditions and was achieved with a temperature of 32 °C, constant pH of 7.0 and salt bridge component concentrations of agar: 8.0 g/100 ml and KCL: 2.9 g/100 ml. The maximum recorded voltage at an external resistance of 30 Ω was 861.27 mV. The current density was 2.16 mA/m2, the power density was 1887.49 mW/m2, and the columbic efficiency was 24.12%.

Twenty-three crude-oil-degrading bacteria were isolated from oil-contaminated sites near the Red Sea. Based on a high growth rate on crude oil and on hydrocarbon degradation ability, four strains were selected from the 23 isolated strains for further study. These four strains were selected on the basis of dichlorophenolindophenol assay. The nucleotide sequences of the 16S rRNA gene showed that these isolated strains belonged to genus Pseudomonas and Nitratireductor. Among the four isolates, strains S5 (Pseudomonas sp., 95%) and 4b (Nitratireductor sp., 70%) were the most effective ones in degrading crude oil. Using a spectrophotometer and gas chromatography–mass spectrometry, degradation of more than 90% of the crude oil was observed after two weeks of cultivation in Bushnell–Haas medium. The results showed that these strains have the ability to degrade crude oil and may be used for environmental remediation.

The ability of different local fungal isolates to degrade kerosene in liquid medium was studied. The results showed that the percent of kerosene degradation varied among the different tested fungi and that 60–96% of kerosene was degraded after 7 days in the presence of 0.2% (v/v) of Tween 80. The absence of the surfactant led to about 28.34% decrease of biodegradation. The degradation of 2% (v/v) of kerosene by the most efficient fungus (Aspergillus flavus) was significantly influenced by the incubation period and the composition of culture medium. Statistical experimental designs were used to optimize the process of kerosene degradation by the fungus. Under optimized medium compositions and culture conditions, A. flavus degraded kerosene (100%) after 111.3 h of incubation. Optimal conditions obtained in this work provided a solid foundation for further use of A. flavus in treatment of kerosene-polluted soil. The optimized conditions were applied to bioremediate 2.5% (v/w) kerosene-polluted soil b...

Lycopene is an effective antioxidant proposed as a possible treatment for some cancers and other degenerative human conditions. This study aims at generation of a yeast strain (Saccharomyces cerevisiae) of efficient productivity of lycopene by overexpressing synthetic genes derived from crtE, crtB and crtI genes of Erwinia uredovora. These synthetic genes were constructed in accordance with the preferred codon usage in S. cerevisiae but with no changes in amino acid sequences of the gene products. S. cerevisiae cells were transformed with these synthetic crt genes, whose expression was regulated by the ADH2 promoter, which is de-repressed upon glucose depletion. The RT-PCR and Western blotting analyses indicated that the synthetic crt genes were efficiently transcribed and translated in crt-transformed S. cerevisiae cells. The highest level of lycopene in one of the transformed lines was 3.3mglycopene/g dry cell weight, which is higher than the previously reported levels of lycopene in other microorganisms transformed with the three genes. These results suggest the excellence of using the synthetic crt genes and the ADH2 promoter in generation of recombinant S. cerevisiae that produces a high level of lycopene. The level of ergosterol was reversely correlated to that of lycopene in crt-transformed S. cerevisiae cells, suggesting that two pathways for lycopene and ergosterol syntheses compete for the use of farnesyl diphosphate.

The influence of solid state fermentation (SSF) by Trichoderma spp. on the solubility, total phenolic content, antioxidant, and antibacterial activities of turmeric was determined and compared with unfermented turmeric. The solubility of turmeric was monitored by increase in its phenolic content. The total phenolic content of turmeric extracted by 80% methanol and water after SSF by six species of Trichoderma spp. increased significantly from 2.5 to 11.3–23.3 and from 0.5 to 13.5–20.4 GAE/g DW, respectively. The antioxidant activities of fermented turmeric were enhanced using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS), and ferric ion-reducing antioxidant power (FRAP) assays. The antibacterial activity of fermented turmeric against human-pathogenic bacteria Escherichia coli, Streptococcus agalactiae, Staphylococcus aureus, Entreococcus faecalis, Methicillin-Resistant S. aureus, Klebsiella pneumonia, and Pseudomonas aeruginosae showed a broad spectrum inhibitory effect. In conclusion, the results indicated the potentials of using fermented turmeric as natural antioxidant and antimicrobial material for food applications.

In this work, sequential optimization strategy, based on statistical designs, was employed to enhance the generation of electricity in microbial fuel cell. For screening of growth medium composition significantly influencing electricity generation, the two-level Plackett–Burman design was used. Under our experimental conditions, glucose, KCl, and NaHCO3 were found to be the major factors of the electricity generation. A near optimum medium formulation was obtained using this method with increased voltage yield by 5.3 %. Response surface methodology was adopted to acquire the best process conditions. In this respect, the three-level Box–Behnken design was applied. A polynomial model was created to correlate the relationship between the three variables (glucose, KCl, and NaHCO3) and voltage yield. Estimated optimum levels of optimized variables for the generation of electricity were glucose 8.5 g/l, KCl 0.8 g/l, and NaHCO3 0.2 g/l. The optimum voltage yield was 738.72 mV which was 8.0 % than the basal medium.

Lipases (triacyl glycerol acyl hydrolase) catalyze hydrolysis and syntheses of ester formed from glycerol and long-chain fatty acids. They have many industrial applications, especially in food and detergent industries. Out of 33 bacterial isolates, a group of 20 bacterial isolates produced lipase enzyme on tributyrin agar and Tween 80 agar media. In liquid medium, the lipase activity was ranged from 1.5 to 6.9 IU/ml. Among the evaluated bacteria, the isolate LP10 that was isolated from soil collected from fuel station. It was the most active isolate in lipase production (6.9 IU/ml). Using morphological, physiological and biochemical studies, it was identified as an isolate belonging to the genus Streptomycesand identified as Streptomyces exfoliates LP10. Identification was confirmed using 16S rDNA analysis. Growth of the selected bacterium in medium containing tributyrin and Tween 60 at initial pH 6 in addition to incubation at 37°C for three days yielded the maximum lipase production. The molecular weight of the purified enzyme was 60 kDa, determined using gel electrophoresis. Improvement of lipase production was carried out between Streptomyces exfoliates LP10 and Streptomyces niveus using protoplast fusion. Five fusants were obtained. Fusant LP3 was the best lipase producer (3 times higher) compared to its parents. Key words: Lipase, Streptomyces exfoliates, tributyrin, protoplast fusion, 16S rDNA.

Background: Molecular characterization of staphylococcal cassette chromosome mec (SCCmec) types of methicillin-resistant Staphylococcus aureus (MRSA) is very essential for studying the epidemiology of MRSA. Objectives: This study reports two multiplex PCR for molecular typing of MRSA collected from Jeddah, Kingdom of Saudi Arabia. Materials and Methods: A total of 101 clinical isolates of strains were collected from major hospital laboratories and public health centres, Jeddah, Kingdom of Saudi Arabia during the period from August 2009 to May 2011. All the strains were tested phenotypically by conventional methods and genotypically by a novel multiplex PCR targeting at the same time S. aureus 16S rRNA, Panton - valentine leucocidin (PVL) and mecA resistance genes. All the strains were tested also by multiplex PCR for typing of SCC mec types. Results: All the 101 strains previously identified phenotypically as S. aureus with bacteriological examination were positive for amplification of 756 base pair fragments specific for 16S rRNA of S. aureus. Moreover, all the strains were positive for amplification of 1339 base pair fragments specific for mecA gene, while only 38 strains (37.6%) showed positive amplification of 433 base pair fragments specific for PVL gene. The most predominant SCC mec type among the examined isolates is type V 43 (42.5) followed by SCCmec type III 39 (38.6%). Conclusion: The newly modified multiplex PCR is rapid and sensitive method for detection of MRSA. Moreover, the most predominant SCC mec type among the examined isolates from Jeddah, King Saudi Arabia is type V (42.5%), followed by Type III (38.6%).

Thirty bacterial isolates were obtained from different sources and sites at Jeddah, Saudi Arabia, on chitin agar medium; 9 of the 30 isolates were cultured in liquid medium containing chitin as sole carbon and nitrogen sources. Isolate SM21, which was isolated from shrimp shells, showed the best growth and chitinase production in liquid medium. According to its morphological, physiological and biochemical characteristics, SM21 belongs to the genus Streptomyces and was identified as Streptomyces anulatus SM21. Identification was confirmed using 16S rDNA analysis. The chitinase enzyme was precipitated with 80% NH4SO4 and purified using DEAE-cellulose ion exchange chromatography followed by Sephadex G-100 gel filtration. The molecular weight determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis was 28 kDa. Genetic improvement using the protoplast fusion technique was carried out between the identified Streptomyces isolate and Streptomyces coelicolor SM1. These two species, which have different resistance profiles to streptomycin and tetracycline (400 μg/ml and 10 μg/ml, respectively), were used in an intraspecific protoplast fusion using PEG 6000. The percentage of real protoplasts that could regenerate successfully was 71% for S. coelicolor SM1 and 80% for S. anulatus SM21. Out of three recombinant fusants obtained, one (named Fu3) showed higher chitinase production compared to both parents (5 fold increase).

Uricase plays an important role in nitrogen metabolism and can be used medically as a diagnostic reagent. From soil, wastewater, and poultry waste samples collected in Jeddah, 49 bacterial isolates were obtained on either nutrient agar or starch nitrate agar. All the obtained isolates were screened on minimal medium containing 0.5% uric acid for uricase production. The most active bacterium (isolate UR10) produced about 0.5 U/mL of intracellular uricase and was identified as a species belonging to the genus Streptomyces using morphological, physiological, and biochemical characters. By 16S rDNA, it was identified as Streptomyces exfoliatus UR10. Maximum uricase production was obtained using medium 2 with 0.2% uric acid as an inducer, an initial pH of 6.5, and an incubation temperature of 37 °C at 100 rpm. At the end of the incubation period, the cells were collected and disturbed, and the uricase enzyme was precipitated by ammonium sulfate. The enzyme was purified using different column chromatography methods, and the molecular weight of the purified uricase was determined by SDS-PAGE electrophoresis. The optimum temperature for maximum uricase activity was 45 °C; the optimum pH was 8. Co2+, Ni2+, Zn2+, Cu2+, and Pb2+ decreased the enzyme activity, whereas Ca2+, Mn2+, Mg2+, and Fe2+ stimulated it. In conclusion, uricase was produced by Streptomyces in a medium containing uric acid as inducer, and this enzyme can be used to detect and quantify uric acid in urine and/or blood.

Different solid state fermentation (SSF) sources were tested such as cantaloupe and watermelon rinds, orange and banana peels, for the production of polygalacturonase (PG) and xylanase (Xyl) by Trichoderma harzianum and Trichoderma virens. The maximum production of both PG and Xyl were obtained by T. harzianum and T. virnes grown on cantaloupe and watermelon rinds, respectively. Time course, moisture content, temperature, pH, supplementation with carbon and nitrogen sources were optimized to achieve the maximum production of both PG and Xyl of T. harzianum and T. virens using cantaloupe and watermelon rinds, respectively. The maximum production of PG and Xyl of T. harzianum and T. virens was recorded at 4–5 days of incubation, 50–66% moisture, temperature 28–35°C and pH 6–7. The influence of supplementary carbon and nitrogen sources was studied. For T. harzianum, lactose enhanced PG activity from 87 to 120 units/g solid, where starch and maltose enhanced Xyl activity from 40 to 55–60 units/g solid for T. virnes. Among the nitrogen sources, ammonium sulphate, ammonium nitrate, yeast extract and urea increased PG activity from 90 to 110–113 units/g solid for T. harzianum. Similarly, ammonium chloride, ammonium sulphate and yeast extract increased Xyl activity from 45 to 55–70 units/g solid for T. virens.

Acinetobacter baumannii, Corynebacterium sp., Cytophaga columnaris, Escherichia coli,Pseudomonas fluorescence and Pseudomonas luteola were locally isolated bacteria from sewage Disposal Lake at Jeddah, Saudi Arabia and they can decolorize methylene blue.E. coli was the most potent MB decolorizing and to a lesser extend P. luteola. Five different media were tested to elucidate medium formulation in favor of MB decolorization by E. coli and P. luteola. Ingredients of the basal medium favored the complete decolorization of 50 µ QUOTE QUOTE g MB/ml after 84 h of fermentation. Time course decolorization of MB by E. coli indicated that 75 h of fermentation was satisfactory to decolorize 50 µ QUOTE QUOTE g MB/ml. It was also able to decolorize different levels of MB up to 150 µ QUOTE QUOTE g MB/ml after 95 h of fermentation. Bacterial consortium of E. coli and P. luteola was highly efficient to decolorize MB than monoculture, where the decolorization period reduced by more than 37% and increased decolorization rate (µgMB/h) up to 58%. Statistical designs of two phase multifactorial optimization (Plackett-Burman and Box-Behnken) were carried out to optimize cultural conditions to increase the efficiency of mixed culture to decolorize 150 µg MB/ml. Under the optimized conditions the decolorization period was reduced by about 31.7% and with increased decolorization rate by 46.4%. Methylene blue can be efficiently decolorized by facultative aerobic bacteria (E. coli and P. luteola). The decolorization process was markedly influenced by the composition of the fermentation medium and concentration of MB. Mixed culture of E. coli and P. luteola was highly efficient to decolorize MB than monoculture technique. The cultural conditions were considerably optimized using statistical experimental designs of Plackett-Burman and Box-Behnken. Key words: Methylene blue, Escherichia coli, Pseudomonas luteola, mixed culture, statistical optimization.

This study focus on the production of antibacterial compound from Trichoderma spp. Screening of antibacterial activities in some Trichoderma spp. was investigated using CYS80 medium. Trichoderma reesei and Trichoderma viride were highly effective toward human-pathogenic bacteria tested. T. viride and T. reesei were separately applied on Sephacryl S–200 column. Column fractions No. 56 to 64 for T. viride and fractions No. 57 to 66 for T. reesei had inhibitory effect against the most pathogenic bacteria examined. T. reesei and T. viride Sephacryl S-200 fractions with antibacterial activity were analyzed byGas chromatography–mass spectrometry (GC- MS). The product with highest peak (95%), using different libraries, was kojic acid. The yield of kojic acid crystals from T. reesei and T. viride Sephacryl S-200 fractions were 3 and 5 g/L, respectively. Physical analysis of kojic acid with respect to UV, IR, 1HNMR analysis and melting point was examined. The minimum inhibitory concentration (MIC) of kojic acid and augmentin, as control, against human-pathogenic bacteria were evaluated. Kojic acid and augmentin showed a similar time-killing kinetics with human-pathogenic bacteria. The level of kojic acid increased with decreased level of reducing sugar during the growth of T. reesei and T. viride suggesting that the enzyme system for the synthesis of kojic acid found in the cell of these fungi. Key words: Trichoderma spp., human-pathogenic bacteria, kojic acid, minimum inhibitory concentration.

The biosorption of lead by two Gram-ve bacteria, either non-capsulated (Citrobacter freundii ) or capsulated (Klebsiella pneumoniae) was characterised. Lead biosorption was found to be influenced by the pH of the solution, initial metal concentration, and amount of the dried powdered cells and contact time. Thus, the optimum biosorption capacity, by the two tested bacteria, was attained at pH 4, initial lead concentration of about 481.2 mg/ℓ and contacted with 2 g dried cells/ℓ for 100 min. However, the dried powdered cells of both organisms can be safely stored for long periods (125 d) at room temperature (25 ± 2ْC) without any loss of their biosorption efficiency, i.e. their binding sites not affected by storage. The results revealed that the presence of capsule (K. pneumoniae) increased the biosorption efficiency of the bacterium. Water SA Vol.31 (3) 2005: pp.345-350

Eight isolates identified as belonging to the genus Bacillus were obtained from Aloqt (a crusty dried product made from goat milk). The cell-free culture supernatant (CFCS) from the eight isolates possessed an inhibitory spectrum against Staphylococcus aureus and Escherichia coli. The eight unknown bacterial isolates were identified by PCR amplification of their 16S ribosomal RNA gene and sequencing of the resulting PCR products. All of the isolates were classified as members of Bacillus amyloliquefaciens, as their 16S rDNA similarities to the respective species were greater than 99%. The phylogenetic analysis grouped two isolates with strain BCRC 11601 and the remaining six isolates with strains MPA 1034 and BCRC 11601. The inhibitory activity of the CFCS was either highly reduced or fully inactivated when treated by proteolytic enzymes, suggesting the possible involvement of a protein/polypeptide bacteriocin-like inhibitory substance (BLIS) in their antagonism. The optimum growth conditions for maximum inhibitory activity were achieved at an initial pH of 7, incubation temperature of 37 °C, and NaCl concentration of (1%). A considerable decrease and/or complete loss of activity occurred at values above and below the optimum. The maximum inhibitory activity occurred after 24 h of incubation; as the incubation time increased, a decrease in the activity was observed until a complete loss of activity occurred after 72 h of incubation.