Bacteria isolated from a sugarcane agroecosystem: their potential production of polyhydroxyalcanoates and resistance to antibiotics

Abstract

In this investigation, a sugarcane agroecosystem at a coastal tableland, in the northeast of Brazil, was screened to obtain bacteria strains able to synthesize poly-β-hydroxyalkanoates (PHA), using sucrose as the main carbon source. The potential to synthesize PHA was tested qualitatively by Sudan Black staining of colonies growing in different carbon sources: sucrose, glucose, fructose, propionate and cellulose. In a typical sugarcane crop management system, the plantation is burned before harvesting and vinasse, a by-product of alcohol production, is used in a fertirrigation system causing, probably, selective pressures on the microbiota of natural environments. Eighty-two bacteria strains, belonging to 16 different genera and 35 different species, were isolated. The data showed that 11 strains (ca 13%), nine of which belonging to the genus Pseudomonas, presented a strong Sudan Black staining in several carbon sources tested and, simultaneously, showed multiple resistance to antibiotics. Resistance to antibiotics is an advantageous feature for the biotechnological production of PHAs. The total number of isolates with multiple resistance to antibiotics was 73, and 38% of them belong to the genus Pseudomonas. Among the isolates, ca 86% and 43% grew in the presence of 10-100 U/ml of penicillin and/or 100-300 mg/ml of virginiamycin, respectively. These antibiotics are utilized in the alcohol distillery we investigated. The results suggest that some agroecosystem environments could be considered as habitats where bacteria are submitted to nutritional unbalanced conditions, resulting in strains with potential ability to produce PHAs, and also, to an increase in the microbial diversity.

Screening of different contaminated environments for polyhydroxyalkanoates-producing bacterial strains

“…The major cost of PHA production is the substrate and the separation process (Bruce et al 1990). De Lima et al (1999) studied different PHA-producing bacterial strains isolated from a sugarcane agro-ecosystem for their resistance to certain antibiotics. Choosing an antimicrobial with the desirable selective toxicity is difficult and the exact amount to be applied must previously be deter-Characterization of polyhydroxyalkanoates-producing bacterial strains 651 mined since an excessive concentration may modify the global performance of the microorganism of interest or remain in the product altering its properties (Oliveira et al 2000).…”

Antibiotics Sensitivity and Heavy Metals Resistance in PHB-Producing Bacilli Isolated from Eastern Province, Saudi Arabia

“…Sixteen strains showed blue-black colonies with Sudan black stain (non-specific for any lipid particles) and colonies with red fluorescence after staining with Nile Red and exposure to UV (specific for PHB). Generally, the dynamic status of our ecosystem contaminates soils with large diversity of PHB-producing bacteria (De Lima et al, 1999). Chen reported the tremendous activity of bacteria in production of polyhydroxyalkanoates as a promising polymer for drug delivery and as biofuel (Chen, 2010).…”

“…De Lima et al (1999) mentioned that PHA biopolymers production in industrial scale is strongly affected by heavy contamination from environment in the fermenter. Therefore, it is highly crucial to exploit the potent biopolymer producing strains regarding antibiotics and heavy metal resistance for controlling contamination before industrial production of the polymer (De Lima et al, 1999;Rehman et al, 2007;Razzaq et al, 2010;Naheed et al, 2011).…”

Enhanced Agarose and Xylan Degradation for Production of Polyhydroxyalkanoates by Co-Culture of Marine Bacterium, Saccharophagus degradans and Its Contaminant, Bacillus cereus

“…Selective staining of PHA granules is commonly carried out by dyes Nile Red and Nile Blue A [36,50,51]. The bacterial cells cultured for 100 h at 30 • C were used to prepare heat-fixed smears.…”