Source For Isolation Of Bacteria Research Articles

Polyhydroxyalkanoate production from rice straw hydrolysate obtained by alkaline pretreatment and enzymatic hydrolysis using Bacillus strains isolated from decomposing straw

Rice straw is an important low-cost feedstock for bio-based economy. This report presents a study in which rice straw was used both as a source for isolation of bacteria producing the biodegradable polyester polyhydroxyalkanoate (PHA), as well as the carbon source for the production of the polymer by the isolated bacteria. Of the 100 bacterial isolates, seven were found to be positive for PHA production by Nile blue staining and were identified as Bacillus species by 16S rRNA gene sequence analysis. Three isolates showed 100% sequence identity to B. cereus, one to B. paranthracis, two with 99 and 100% identity to B. anthracis, while one was closely similar to B. thuringiensis. For use in PHA production, rice straw was subjected to mild alkaline pretreatment followed by enzymatic hydrolysis. Comparison of pretreatment by 2% sodium hydroxide, 2% calcium hydroxide and 20% aqueous ammonia, respectively, at different temperatures showed maximum weight loss with NaOH at 80 °C for 5 h, but ammonia for 15 h at 80 °C led to highest lignin removal of 63%. The ammonia-pretreated rice straw also led to highest release of total reducing sugar up to 92% on hydrolysis by a cocktail of cellulases and hemicellulases at 50 °C. Cultivation of the Bacillus isolates on the pretreated rice straw revealed highest PHA content of 59.3 and 46.4%, and PHA concentration of 2.96 and 2.51 g/L by Bacillus cereus VK92 and VK98, respectively.

A prospective study of seven patients with chronic mastoiditis

Introduction: Chronic mastoiditis is generally a result of chronic suppurative otitis media; it is rarely a result of failure of treatment of acute mastoiditis. Case presentation: Seven patients with chronic mastoiditis were investigated. Four patients had bilateral mastoiditis. The duration of illness ranged from 1 to 45 years. A comparison between operative and external auditory canal cultures was performed. The operative specimens were obtained directly from the infected mastoids. The external ear and mastoid specimens were inoculated and cultivated immediately by bedside. All cases showed positive bacterial cultures. The growth was monomicrobial in two cases and polymicrobial in five cases. Seventeen isolates were recovered (11 aerobes and six anaerobes). Pseudomonas aeruginosa was the most predominant isolate (23.5 %) and was recovered from four patients (57 %). This high prevalence may be related to misuse of ear drops that transmit this organism from skin flora towards the mastoid. The anaerobes were isolated from four patients. This may indicate a significant role of anaerobic bacteria in producing chronic mastoiditis that would not respond to usual treatment measures. Conclusion: Cultures from external ear canal discharge might be used as a source for isolation of bacteria causing chronic mastoiditis and chronic otitis media provided that the specimen was collected and cultivated properly. They revealed sensitivity (88 %), specificity (100 %), positive predictive value (100 %) and negative predictive value (66 %). In anaerobic cultures, the sensitivity was 66.7 %. No previous studies were found with regard to evaluation of the reliability of external ear culture for isolation of the causative agents of chronic mastoiditis or chronic otitis media.

Utilization of millet and guinea corn husks for bioethanol production

In this study, the rumen of ruminant animals served as a source for isolation of bacteria used in the hydrolysis of millet husks and guinea corn husks prior to fermentation. The isolates were characterized and identified as Bacillus firmus, Bacillus circulans, Escherichia coli, Proteus rettgerii, Paenibacillus macerans and Serratia marcescens.Zymomonas mobilis and Saccharomyces cerevisiae isolated from a previous study were used as the fermentative organisms. The production of bioethanol was done by hydrolysis and fermentation. The results obtained revealed that highest yield of reducing sugar of (4.10%) was obtained from guinea corn husk while the reducing sugar yield of millet husk was 3.21%. The highest concentration of bioethanol of (2.33%) was produced using the combination of S. cerevisiae and Z. mobilis for fermentation of guinea corn husks. Similarly, the lowest concentration of 0.79% was obtained when Z. mobilis was used on hydrolysates from millet husk. The results of the study revealed the potentiality of the two agro wastes to produce bioethanol. However, guinea corn husk is more promising than millet husk as it produces more bioethanol and can be used for large scale production. Key words: Bioethanol, millet husk, guinea corn husk, Saccharomyces cerevisiae,Zymomonas mobilis.