Silicosis — Continued Silicosis is a chronic lung disease associated with the inhalation and pulmonary deposition of dust that contains crystalline silica. Through the Sentinel Event Notification System for Occupational Risks (SENSOR)* program, CDC's National Institute for Occupational Safety and Health (NIOSH) is assessing practical models for implementing state-based surveillance of silicosis and linking follow-up intervention activities to surveillance reports. From 1989 through 1992, the Ohio Department of Health (ODH) SENSOR program identified silicosis cases through reports of Bureau of Workers' Compensation (BWC) claims, physician reports, and death certificates. The addition in 1993 of hospital discharge reports as an ascertainment source resulted in a substantial increase in the number of silicosis case reports identified annually (Table 1). This report describes the investigation of a case of occupational silicosis in Ohio and summarizes the impact of hospital-based reporting on surveillance for silicosis in Case Report In September 1991, a case report † was sent to ODH by an infectious disease specialist who was treating a 55-year-old sandblaster with advanced silicosis and an associated Mycobacterium kansasii infection § (2). In January 1992, NIOSH and ODH conducted a joint investigation at the worker's place of employment—a metal preparation shop—to evaluate current levels of exposure to respirable crystalline silica and to screen co-workers for silicosis. The investigation detected excessive exposures to respirable crystalline silica (2–5). Chest radiology revealed radiographic abnormalities consistent with pneumoconiosis in four of 16 current and former workers *SENSOR is a program of cooperative agreements with state health departments to develop surveillance and intervention strategies for selected occupational conditions. The National Institute for Occupational Safety and Health currently supports SENSOR silicosis programs in seven states and Wisconsin). † Case reports should be submitted for persons with a physician's provisional diagnosis of silicosis, a chest radiograph interpreted as consistent with silicosis, or pathologic findings consistent with silicosis (1).

Current trends in

Melanin pigments are frequently used in medicine, food and cosmetic preparations. In this study, three strains among 21 Actinomycetes sp isolates produced a diffusible dark pigment on starch casein an agar medium which was water soluble. The pigment production was estimated using L-tyrosine as substrate. Among the strains, 3 (F1, F2, F3) were used for further analysis. Optimized culture condition for melanin production were; 1% of starch- best carbon source, 0.2% of soyabean- best nitrogen source, salinity- 15 ppt, temperature- 35°C, pH-7.0 and incubation time- 168 h. Sugarcane waste was found to be the cheaper and best source for melanin production. Melanin also showed activity against potential pathogens. The maximum antimicrobial activity was observed with Escherichia coli (20 mm) and Lactobacilus vulgaris (20 mm). F1 strain producing melanin was taken for FT-IR analysis. The FT-IR result confirmed that it was melanin pigment. Therefore, this study proved that sugarcane waste can be used for the production of melanin and it (melanin) has potential anti-bacterial activity.

	 

	Key words: Melanin, sugarcane waste, antibacterial, FT-IR.

Melanin production from marine Streptomyces

Losses in crops caused by plant pathogenic bacteria and parasitic nematode are increasing because of a decrease in efficacy of traditional management measures. There is an urgent need to develop nonchemical and ecofriendly based management to control plant diseases. A potential approach of controlling plant disease in the crops is the use of biocontrol agents and their secondary metabolites (SMs). Luckily fungi and especially the genus Trichoderma comprise a great number of fungal strains that are the potential producer of bioactive secondary metabolites. In this study secondary metabolites from ten Trichoderma spp. were evaluated for their antibacterial and nematicidal potential against phytopathogenic bacteria Ralstonia solanacearum, Xanthomonas compestris and plant parasitic nematode Meloidogyne incognita. Five different growth media were evaluated for the production of SMs. It was shown that SMs of different Trichoderma spp. obtained on different growth media were different in the degree of their bioactivity. Comparison of five growth media showed that SMs produced on solid wheat and STP media gave higher antibacterial activity. SMs of T. pseudoharzianum (T113) obtained on solid wheat media were more effective against the studied bacteria followed by SMs from T. asperelloides (T136), T. pseudoharzianum (T129) and T. pseudoharzianum (T160). Scanning electron microscopy (SEM) was further conducted to observe the effect of SMs on bacterial cell morphology. As evident from the SEM, SMs produced severe morphological changes, such as rupturing of the bacterial cell walls, disintegration of cell membrane and cell content leaking out. SMs from T. viridae obtained on liquid STP and solid wheat media showed the highest percent of M. incognita juveniles (J2s) mortality and inhibition in egg hatching of M. incognita. The results of our study suggest that T. pseudoharzianum (T113) and T. viridae could be selected as an effective candidate for SMs source against phytopathogenic bacteria and M. incognita respectively.

https://www.mdpi.com/2076-2607/8/3/401/pdf

Bioactive Secondary Metabolites from Trichoderma spp. against Phytopathogenic Bacteria and Root-Knot Nematode

Growth p attern and antimicrobial p rofile of Nocardia levis MK-VL_113 were studied on Yeast extract-Malt extract -Dextrose broth. An attempt has been made to evaluate the optimal cultural conditions for ob taining high yields of bioactive m etabolites. The o ptimum temperature and pH for bi oactive metabolite p roduction of the st rain were recorded as 30 C and 6.5 respectively. Production of bioactive o metabolites by the strain was high in maltose tryptone broth as compared to other tested media tested. The strain ut ilized sucrose and tryptone as good carbon and nitrogen sources for t he el aboration of bioactive metabolites. The secondary metabolites exhibited hi gh antimicrobial activity against a v ariety of Gram positive, Gram negative bacteria and fungi. This is the first report on the optimization studies of bioactive metabolites b y N. levis.

Cultural parameters affecting the production of bioactive metabolites by Nocardia levis MK-VL_113

4 different actinomycetes strains (A1, A2, A3 and A4) were isolated from the laterite soil samples of Guntur region. Growth pattern and antifungal profiles of the strains were evaluated against the test fungi such as Aspergillus flavus, Aspergillus niger,Candida albicans and Fusarium oxysporum. Based on the cultural, morphological and physiological characteristics, the strains A1, A2 and A4 were identified as the species of Streptomyces while the strain A3 was assigned to Nocardia.  Among the 4 tested strains, Streptomyces sp. A1 showed strong antifungal activity which may provide a potent source for antifungal metabolites.

	 

	Key words: Actinomycetes, Streptomyces, Nocardia, antimicrobial activity.

Screening of actinomycetes strains for the production of antifungal metabolites.

Screening of Antagonistic Activity in Different Streptomyces Species Against Some Pathogenic Microorganisms

The present study was carried out to investigate the physical and nutritional factors affecting the growth and antifungal activity of three Streptomyces species (S. fradiae, S. lavendulae and S. fulvissimus) against C. albicans. Starch was the best carbon source for all Streptomyces spp., whereas the other tested C-sources gave varying amounts of growth and antifungal activity. Addition of mannitol to the media as sole C-source inhibited growth and antifungal activity of both S. fradiae and S. lavendulae. Potassium nitrate followed by peptone, NH 4 H 2 PO 4 and NH 4 NO 3 were the most suitable N-sources in case of S. fradiae, whereas Ca(NO 3 ) 2 , NH 4 NO 3 and peptone were the best N-sources for the other two species. Maximum antifungal activity was recorded at starch:KNO 3 ratio 1:1, incubation temperature 30oC and pH 7. This activity was completely inhibited at low temperatures (5-15oC) and pH 4 in the tested species.

Factors affecting growth and antifungal activity of some Streptomyces species against Candida albicans

Different natural raw materials were investigated for their suitability in production of antibiotics by Streptomyces lavendulae which antagonize C. albicans growth. Fish meal extract was the most favourable for growth and antibiotic production by S. lavendulae. Six antibiotics, ileumycin, mitomycin C, eurymycin, glomecidin, SL-1 pigment and saframycin A, are produced by S. lavendulae depending on the composition of the induction medium. Maximum production of ileumycin and SL-1 pigment was recorded after 5 days incubation, whereas the highest activities of mitomycin C, eurymycin and glomecidin were recorded after 2-4 days. Saframycin A was the strongest antibiotic that caused the highest degree of C. albicans inhibition after 20 hours. Addition of chloramphenicol concentrations of 30 and 45 mg/ml at pH 5.75 increased the production of saframycin A.

Antibiotics production by Streptomyces lavendulae under different cultural conditions

Effect of media composition on laccase production by Pleurotus ostreatus in batch culture.

Media variations including eight variables were optimized for improvement of exotoxin production by Pseudomonas aeruginosa, using the statistical design Taguchi system. Eighteen experimental trials with final layout of L 18 (1 2 x 7 3 ) were used. The bacterial toxin production varied significantly among media within range of 1.0-31.0 µg ml -1 . This indicated the validity of optimization design in bioprocesses. The statistical design showed little variations between the actual experimental values and the Taguchi software predicted values. The (ANOVA) analysis implies “P-value” of 10.4 which revealed that the design model is significant. The F-value (less than 0.05) revealed that temperature, agitation and interaction between incubation period and beef extract are the most significant model terms. The regression values of the classical sum of squares indicated that predicted-R 2 (0.6208) and the adjusted-R 2 (0.8341) were in reasonable agreement which indicates the accuracy of experimentation. The predicted optimum medium from the Taguchi software database was beef extract 4 g l -1 , NaCl 7 g l -1 and peptone 3 g l -1 , incubation period 36 h, pH 6.5, temperature 27 o C, inoculum size 3% and agitation 150 rpm.

Tahany Abdel-Rahman

Papers

Screening of Antagonistic Activity in Different Streptomyces Species Against Some Pathogenic Microorganisms

Factors affecting growth and antifungal activity of some Streptomyces species against Candida albicans

Antibiotics production by Streptomyces lavendulae under different cultural conditions

Effect of media composition on laccase production by Pleurotus ostreatus in batch culture.

Production medium optimization for enhancement the exotoxin secretion by Pseudomonas aeruginosa