The excessive use of fertilizers in agriculture is mainly due to the recognized plant requirements for soluble phosphorus. This problem has limited the implementation of sustainable agriculture. A viable alternative is to use phosphate solubilizing soil microorganisms. This work aimed to isolate inorganic phosphorus-solubilizing bacteria from the soils of agroecosystems, to select and identify, based on sequencing and phylogenetic analysis of the 16S rRNA gene, the bacterium with the highest capacity for in vitro solubilization of inorganic phosphate. Additionally, we aimed to determine its primary phosphate solubilizing mechanisms and to evaluate its effect on Habanero pepper seedlings growth. A total of 21 bacterial strains were isolated by their activity on Pikovskaya agar. Of these, strain ITCB-09 exhibited the highest ability to solubilize inorganic phosphate (865.98 µg/mL) through the production of organic acids. This strain produced extracellular polymeric substances and siderophores that have ecological implications for phosphate solubilization. 16S rRNA gene sequence analysis revealed that strain ITCB-09 belongs to the genus Enterobacter. Enterobacter sp. ITCB-09, especially when immobilized in beads, had a positive effect on Capsicum chinense Jacq. seedling growth, indicating its potential as a biofertilizer.

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Cadmium is a major heavy metal found in polluted aquatic environments, mainly derived from industrial production processes. We evaluated the biosorption of solubilized Cd2+ using the extracellular polymeric substances (EPS) produced by Bacillus sp. MC3B-22 and Microbacterium sp. MC3B-10 (Microbactan); these bacteria were originally isolated from intertidal biofilms off the coast of Campeche, Mexico. EPS were incubated with different concentrations of cadmium in ultrapure water. Residual Cd2+ concentrations were determined by Inductive Coupled Plasma-Optic Emission Spectrometry and the maximum sorption capacity (Qmax) was calculated according to the Langmuir model. EPS were characterized by X-ray photoelectron spectroscopy (XPS) before and after sorption. The Qmax of Cd2+ was 97 mg g−1 for Microbactan and 141 mg g−1 for MC3B-22 EPS, these adsorption levels being significantly higher than previously reported for other microbial EPS. In addition, XPS analysis revealed changes in structure of EPS after biosorption and showed that amino functional groups contributed to the binding of Cd2+, unlike other studies that show the carbohydrate fraction is responsible for this activity. This work expands the current view of bacterial species capable of synthesizing EPS with biosorbent potential for cadmium and provides evidence that different chemical moieties, other than carbohydrates, participate in this process.

The seaweed Sargassum (Sargassaceae) as tropical alternative for goats' feeding. The nutritive value of seaweed (Sargassum spp.) was studied in Baja California Sur, Mexico. Twenty female Nubian goats (43-weeks old) were randomly distributed into two groups of 10 goats each and were housed in individual pens. One group was fed with a control diet and the other with a diet supplemented with 25% of Sargassum spp. Feed and water intake were recorded daily and individually for 60 days. The weight of each goat was recorded every 15 days. The nutritional content of Sargassum spp. was 89% dry mater, 8% crude protein, 31% ash, 2% ether extract, and 39% carbohydrates. Fiber fractions, minerals, vitamins, fatty acids, and antinutritional factors were also determined. There were no significant differences in body weight (8.6 kg control and 9 kg experimental), feed intake (1.3 kg control and 1.6 kg experimental), and feed conversion rate (11.1 control and 12.6 experimental). Water consumption was greater in the goats that ate the Sargassum diet (5.3 l). From these results, Sargassum spp. can be considered as an alternative feedstuff for goats. Rev. Biol. Trop. 54(1): 83-92. Epub 2006 Mar 31.

The development of novel environmentally friendly antifouling (AF) solutions is a very active field in fundamental and applied research. An attractive option in producing such material resides in biomimetic studies: living organisms have evolved well-adapted structures and materials over geological times through natural selection. In this chapter, we explain the experimental procedure to be followed for the preparation of macroalgal extracts and to assess their AF efficiency towards key species. All bioassays described here have the advantage of being fast, reliable, and standardized.

Changes in the distribution, surface canopy, biomass, and standing crop of Sargassum beds (Phaeophyceae) along the southeastern coast of the Baja California Peninsula (Mexico) are described and compared with previous estimates. Also, Sargassum biomass was correlated with latitude. Species were identified and surface canopy, biomass, standing crop, and length structure were estimated for 72 Sargassum beds in 3 localities in 2006. The extent of each bed was determined using GPS. The perimeter of each bed was drawn and its canopy area was calculated. The average biomass was estimated, using quadrats that were randomly distributed over the beds. The highest average biomass was found at Mulegé, with significant differences in the other 2 study areas (Concepción and La Paz bays). The largest bed, surface canopy area, and standing crop were recorded in Concepción Bay. Coverage area, location, and seasonal changes in surface canopy, standing crop, and biomass of Sargassum beds along the southeastern coast of the Baja California Peninsula were compared with the different phenological stages of Sargassum thalli, variations in the available rocky sea floor, and oceanographic characteristics. These aspects must be considered to maintain sustainable exploitation of this potential resource.

One way of reducing the input of pollutants into the marine environment is to enforce the use of non-toxic antifouling paints in marine protected areas. Thus, the purpose of this study was to detect marine microorganisms that secrete inhibitory substances against bacteria and microalgae to avoid biofouling on man-made structures in La Paz bay, B.C.S., Mexico. The inhibitory potential of 125 bacteria was evaluated against biofilm-forming bacteria. Crude extracts were obtained with methanol and ethyl acetate from 16 bacterial strains that exhibited antagonistic and antibacterial activity in a preliminary screening. Antibacterial and antimicroalgal assays were performed using crude extracts, the minimum inhibitory concentration (MIC) was determined. The highest activity against bacteria and microalgae was found in two strains, Shewanella algae and Staphylococcus sp. The results of this study suggest that extracts of bacteria from the Gulf of California with antimicrobial properties against biofilm-forming bacteria can also prevent the adhesion of microalgae, which may control the development of biofilm formation and, as a consequence, biofouling.