Dr. Yoav Bashan and Dr. Luz Gonzalez de Bashan

The history of how the microalgae-plant growth
promoting bacteria model was born


Date of Birth: 1 January 1998 midday.
Location: Punta Lobos, Todos Santos, Baja California Sur, Mexico

Dra Luz Gonzalez
Luz Gonzalez on the top of Punta Lobos
in first of January 1998; thinking.

In the final days of 1997, Luz Gonzalez, then an Assistant Professor at Potificia Universidad Javeriana in Colombia and Yoav Bashan, a researcher at the Northwestern Center for Biological Research in Mexico had a pending and serious scientific problem. The dilemma was not easy to solve. Luz was working on treating wastewater with microalgae (a simple aquatic plant, named Chlorella) and Yoav was working on enhancing the performance of crops by plant growth-promoting bacteria (PGPB, specifically Azospirillum). These two distinct topics appeared to have nothing in common; they function in different environments and in different disciplines of science. No interaction between the water-dwelling microalgae and any terrestrial PBPB was ever documented in the scientific literature. It was then assumed that none exists. At the time, it was presumed, that these differences were unbridgeable. For Luz, the position of assistant professor at the teaching-intensive Colombian university was very demanding; the only free time to think and do research without constant teaching interruptions was on long research stays in Mexico. To make this possible, there was an urgent need to find a way to bridge the gap between these two themes and to create a long-lasting project.
Dra Luz Gonzalez
The beaches in Todos Santos and Punta Lobos:
the birthplace of the idea.

      In December 1997, Luz was finishing her third research stay in Mexico and about to return to her grinding teaching work in Colombia. The long Christmas holiday period provided some time to think about something else. Travelling abroad or within Mexico during this holiday season is not a good idea. Instead, we went to the beautiful beaches near Todos Santos, then about two hours drive from La Paz. On the morning of New Year’s Day of 1998, everybody in Baja California was home recovering from New Year’s Eve partying. As we intended only go to the beach, we invited Vladimir Lebsky, a Russian electron microscopist working with us and a lady friend visiting from mainland Mexico to join us. We expect a quite, sunny day on the beach, the perfect day to start the New Year--no more than sounds of waves and a small picnic under the brilliant winter sun of Baja. Vladimir and his student disappeared somewhere on the miles of golden beaches and no one else was on that beach.

      To avoid thinking about the problem looming in the future of Luz and because the water is too cold for swimming even in hot Baja California, we climbed up the headland of Punta Lobos at the edge of the beach facing the Pacific Ocean. Once on top, buffeted by the strong wind, we were cautious of moving on the rocks to avoid falling from the cliff top to the rumbling waves below. Standing on the highest position above the beach, we thought about our “unsolvable” problem.
Dra Luz Gonzalez
Luz Gonzalez on the top of Punta Lobos
in first of January 1998; thinking.

      Some ideas emerged and started to take shape. Perhaps we could convince our distinct microorganisms, in a non-natural way, to “cooperate” in wastewater treatment. Our initial idea was very modest. Perhaps we could use these microorganisms to eliminate nitrogenous compounds, some of the major contaminants of wastewater. The technical problems are formidable. The microalgae Chlorella can absorb ammonia and Azospirillum can reduce nitrate to nitrogen gas. But, Chlorella works aerobically (in oxygen) and Azospirillum anaerobically (without oxygen). Furthermore, during the process, Chlorella, like every algae, emits more oxygen to the water, a fact that reduces the ability of Azospirillum to eliminate nitrate. Another unknown obstacle was that these two microorganisms do not naturally co-inhabit, so there is no way to predict what kind of negative interactions they may exert on each other. In a few words, there were more troubles than solutions.

      On that enormous cliff in the blowing wind, we wondered how we could create an artificial “forced cooperation” between partners that do not cooperate. First, to avoid harmful effects, we could separate the two microorganisms from one another. We thought of immobilizing and separating the organisms in polymeric beads. Furthermore, we did not intend to use them at the same time. First, we would use oxygen-breathing Chlorella to devour ammonium. Then, we would change to low oxygen and allow Azospirillum metabolize nitrate. We thought that, in the best of cases, the two microbes would tolerate each other in the artificial association, where we immobilize them in the same polymer material and only change the environmental conditions for their work.
Dra Luz Gonzalez
The beaches in Todos Santos and Punta Lobos:
the birthplace of the idea.

      In our wildest dreams, we could not imagine that these microbes would work together. It was then, incomprehensible to think that they could positively affect the most basic functions of these microorganisms. We did not know this process would create an artificial mutualism (an association in life forms where each partner benefits from the activity of the other partner). Even less did we expect that we would create a very close co-habiting association.

      Perhaps this unpredicted model of the simplest plant and a common bacteria will one day serve science to understand fundamental questions about the interactions between plants and microorganisms.

      More than 14 years after that unorthodox idea emerged on the rock in the beach at Todos Santos and more than 20 scientific publications later, the future prospects of this most unlikely association between microalgae and bacteria is brighter than ever.

Luz and Yoav Bashan
La Paz, Baja California, Mexico
May 2011



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